Journal of Public Health | Vol. 37, No. 2, pp. 286 –294 | doi:10.1093/pubmed/fdu012 | Advance Access Publication February 25, 2014
Trends in lipid profiles among South Korean adults: 2005, 2008 and 2010 Korea National Health and Nutrition Examination Survey Ga Eun Nam1, Kyungdo Han2, Yong Gyu Park2, Youn Seon Choi1, Seon Mee Kim1, Sang-Yhun Ju3, Byung-Joon Ko1, Yang Hyun Kim1, Eun Hye Kim1, Kyung Hwan Cho1, Do Hoon Kim1 1
Department of Family Medicine, Korea University College of Medicine, Seoul, South Korea Department of Biostatistics, Catholic University College of Medicine, Seoul, South Korea 3 Department of Family Medicine, Yeouido St. Mary’s Hospital, College of Medicine, Catholic University of Korea, Seoul, South Korea Address correspondence to Do Hoon Kim, E-mail: [email protected]; Kyung Hwan Cho, E-mail: [email protected] 2
Background This study aimed to investigate recent trends in the prevalence and parameters of dyslipidemia and rates of lipid-lowering medication use in Korean adults. Trends in lipid profiles in subjects with hypertension, diabetes or obesity were also studied. Methods Data from the Korea National Health and Nutrition Examination Survey in 2005, 2008 and 2010 were used in this study. A total of 17 009 subjects participated in this study. Results There was a declining trend in the prevalence of dyslipidemia and an increasing trend in the rates of use of lipid-lowering medication among Korean adults. In both men and women, the age-adjusted mean high-density lipoprotein cholesterol level linearly increased. There was a significantly decreasing trend in the age-adjusted mean triglycerides in women and age-adjusted mean lipid-related ratios in both sexes. The ageadjusted mean total cholesterol level showed a slightly increasing trend and the age-adjusted mean low-density lipoprotein cholesterol level was not changed in both sexes. These patterns persisted among subjects not taking lipid-lowering medication. The favorable trends were also observed in subjects with hypertension, diabetes and obesity. Conclusions Our study showed favorable trends in the prevalence of dyslipidemia and in several lipid profiles among Korean adults. Keywords cardiovascular risk, cholesterol, dyslipidemia, lipid, lipoprotein, trends
Introduction Dyslipidemia is generally defined as an increased level of total cholesterol (TC), triglycerides (TG) and low-density lipoprotein cholesterol (LDL-C) and a decreased level of high-density lipoprotein cholesterol (HDL-C).1 Several recent studies have shown that non-HDL-C level and lipid-related ratios are more susceptible in reflecting the severity and morbidity of coronary heart disease (CHD) than individual lipid and lipoprotein levels. Therefore, they are more meaningful than each lipid level in diagnosis and early prevention of CHD.2 – 4 However, little is known about the trends in non-HDL-C and lipid ratio levels among South Korean population.
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Ga Eun Nam, Clinical Instructor of Family Medicine Kyungdo Han, Researcher of Biostatistics Yong Gyu Park, Professor of Biostatistics Youn Seon Choi, Professor of Family Medicine Seon Mee Kim, Professor of Family Medicine Sang-Yhun Ju, Clinical Assistant Professor of Family Medicine Byung-Joon Ko, Clinical Assistant Professor of Family Medicine Yang Hyun Kim, Clinical Assistant Professor of Family Medicine Eun Hye Kim, Clinical Instructor of Family Medicine Kyung Hwan Cho, Professor of Family Medicine Do Hoon Kim, Professor of Family Medicine
# The Author 2014. Published by Oxford University Press on behalf of Faculty of Public Health. All rights reserved. For permissions, please e-mail: [email protected].
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A B S T R AC T
T R E N DS I N L I P I D P RO F I L E S A M O NG S O U T H KO R E A N A D U LTS
Methods Survey overview and study subjects
The present study was based on data obtained from the KNHANES in 2005, 2008 and 2010. The KNHANES has been conducted periodically by the Division of Chronic Disease Surveillance of the Korea Centers for Disease Control and Prevention (KCDC) since 1998. It is a nationwide survey designed to assess national health and nutrition levels accurately and consists of a health interview survey, a nutrition survey and a health examination survey. This survey selected participants from sampling household units defined on the basis of household registries using a stratified, multistage and probability sampling design with proportional allocation. Of the 10 816 people who participated in the 2005 survey, complete data were obtained from 7597 subjects (70.2%). Likewise, 9744 (77.8%) of 12 528 subjects in 2008 and 8518 (80.4%) of 10 589 subjects in 2010 participated in the survey. We then excluded subjects younger than 19 years of age, subjects with any missing data on lipid profiles and subjects who did not fast for at least 8 h before blood sampling. Finally, data on 5216 subjects from the 2005 survey, 6166 subjects from the 2008 survey and 5627 subjects from the 2010
survey were used in the analyses. All of the study participants provided written informed consent, and the institutional review board of the KCDC approved the study protocol. Anthropometric and laboratory measurements
Trained staff performed a physical examination following standard procedures. Body weight and height were measured to the nearest 0.1 kg and 0.1 cm, respectively, while the subjects were wearing light clothing but no shoes. Body mass index (BMI) was calculated as weight in kilograms divided by the square of the height in meters. Systolic blood pressure and diastolic blood pressure were measured using a standard mercury sphygmomanometer. Blood samples were taken after the subjects fasted for 8 or more hours. The samples were immediately centrifuged and refrigerated and then transported in cold storage to the Central Testing Institute in Seoul, Korea and analyzed within 24 h. The serum levels of TC, HDL-C, TG and fasting plasma glucose were measured enzymatically using an Advia 1650/2400 (Siemens, New York, NY, USA) in the 2005 survey and a Hitachi Automatic Analyzer 7600 (Hitachi, Tokyo, Japan) in the 2008 and 2010 surveys. LDL-C level was calculated using Friedewald’s equation for subjects with serum TG levels ,400 mg/dl and was measured directly using commercially available kits (Cholestestw LDL, Sekisui Medical, Tokyo, Japan) when TG levels were 400 mg/dl. Non-HDL-C was calculated as serum TC level minus HDL-C level. Definition of dyslipidemia, hypertension, diabetes and obesity
According to the criteria of the National Cholesterol Education Program Adult Treatment Panel III, dyslipidemia was diagnosed when participants met one or more of the following criteria: (i) TC level 240 mg/dl on the blood test after fasting, (ii) HDL-C level ,40 mg/dl, (iii) LDL-C level 160 mg/dl, (iv) TG level 200 mg/dl and (v) the use of lipid-lowering medication or diagnosis of dyslipidemia by a physician.17 Hypertension was defined by blood pressure 140/ 90 mmHg or treatment with antihypertensive medication. Diabetes was defined by fasting plasma glucose level 126 mg/dl, current use of insulin or oral hypoglycemic agents, or diagnosis by a physician. We defined obesity as a BMI 25 kg/m2.18,19 Statistical analyses
Statistical analyses were conducted using the SAS survey procedure (version 9.2; SAS Institute, Cary, NC, USA) to reflect
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Dyslipidemia is one of the most important risk factors for CHD and stroke. Many prior studies have demonstrated that morbidity and mortality from these diseases can be reduced by lowering the blood cholesterol level.5 – 10 Although mortality from CHD has decreased in developed countries, it has been rapidly rising in developing countries such as South Korea, China and other Asian countries over recent decades.11,12 CHD is now one of the leading causes of death, and the age at onset of CHD or stroke has been reported to be decreasing in South Korea, resulting in a higher lifetime disease burden. Therefore, more effective strategies are needed for prevention of CHD and stroke.13 – 15 In South Korea, the prevalence of dyslipidemia in adults has continuously increased from 32.4% in 1998 to 44.1% in 2005.16 However, there have been no subsequent updates of the prevalence of dyslipidemia and trends in lipid profiles, including the aforementioned novel parameters of dyslipidemia. Therefore, this study aimed to investigate recent trends in lipid profiles including lipid ratios and the prevalence of dyslipidemia in Korean adults based on nationally representative data from the 2005, 2008 and 2010 Korea National Health and Nutrition Examination Survey (KNHANES). We also examined trends in rates of use of lipid-lowering medication and trends in lipid profiles in subjects not treated with lipid-lowering medication. Additionally, trends in lipid profiles in Korean adults with hypertension, diabetes or obesity were studied.
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J O U RN A L O F P U B LI C H E A LT H
Trends in the prevalence of dyslipidemia
The trends in the prevalence of dyslipidemia in Korean adults between 2005 and 2010 are presented in Fig. 1. The prevalence of dyslipidemia decreased from 44.7% in 2005 to 41.3% in 2010 (P for trend ,0.001), and these trends persisted in both sex groups. The prevalence declined linearly from 53.4% in 2005 to 50% in 2010 in men (P for trend ,0.001) and from 36.1% in 2005 to 32.5% in 2010 in women (P for trend ¼ 0.002). Additional information on the prevalence of dyslipidemia by age group is shown in Supplementary data, Table S1; the prevalence of dyslipidemia appears to be in a declining trend, particularly in younger-aged men and youngerand middle-aged women. Trends in the use of lipid-lowering medication
Figure 1 also shows trends in the use of lipid-lowering medication. The overall proportion of subjects treated with lipid-lowering medication increased linearly from 1.36% in 2005 to 2.92% in 2008 and to 5.34% in 2010 (P for trend ,0.001). These trends continued in both men and women (P for trend ,0.001).
Results Trends in lipid profiles
Table 1 presents the trends in age-adjusted means of lipid profiles for Korean adults according to sex and age. The age-adjusted mean TC level for both men and women increased linearly from 2005 to 2008 and to 2010 (P for trend ¼ 0.026 for men and 0.006 for women). Statistically significant increasing trends in age-adjusted mean TC levels were observed in men aged 40–65 years (P for trend ¼ 0.009) and in women aged 19–40 years (P for trend ¼ 0.006). The age-adjusted mean HDL-C level increased linearly in both men and women between 2005 and 2010 (P for trend ,0.001). Increasing linear trends in age-adjusted mean HDL-C levels were observed in young- and middle-age groups in men and all age groups in women. The age-adjusted geometric mean TG level for men did not change significantly in any age group. However, in women, declining trends in the age-adjusted mean TG level were observed (P for trend ,0.001). Young- and middle-aged women had significantly decreasing geometric means of TG level during this period (P for trend ¼ 0.024 and ,0.001, respectively). As for lipid ratios, the age-adjusted mean ratios of TC/HDL-C and LDL-C/HDL-C showed decreasing trends in all age groups for both sexes. The geometric mean TG/ HDL-C ratios also showed decreasing trends in both men and women, and the trends persisted in the younger- and middleage groups for both sexes. From 2005 to 2010, the age-adjusted mean levels of LDL-C and non-HDL-C showed no significant changes in all age groups for both sexes.
Trends in lipid profiles in subjects not taking lipid-lowering medication
Table 2 shows trends in age- and sex-adjusted mean levels of lipid profiles among subjects not treated with lipid-lowering medication. The age- and sex-adjusted mean HDL-C level increased linearly across the survey years (P for trend ,0.001). Age- and sex-adjusted geometric mean TG and TG/HDL-C levels and means of TC/HDL-C and LDL-C/HDL-C ratios showed significantly declining trends. However, there was an increasing trend for age- and sex-adjusted mean TC levels in these subjects. Trends in lipid profiles according to use of lipid-lowering medication in subgroups with hypertension, diabetes and obesity
Table 3 shows trends in mean levels of lipid profiles according to use of lipid-lowering medication in subgroups with conventional CVD risk factors such as hypertension, diabetes and obesity. Among hypertensive subjects, the age- and sexadjusted mean HDL-C level significantly increased linearly and the age- and sex-adjusted mean TC/HDL-C, LDL-C/ HDL-C and geometric mean TG/HDL-C ratios decreased linearly across the survey years. Similar trends were observed in hypertensive subjects who did not use lipid-lowering medication. In subjects with diabetes, there were linearly decreasing trends in age- and sex-adjusted mean TC, LDL-C and
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the complex sampling design and sampling weights of KNHANES and to provide a nationally representative estimate of prevalence. Mean levels of TC, HDL-C, LDL-C, non-HDL-C level and lipid ratios, and the proportions of dyslipidemia and treatment with lipid-lowering medication are presented as least square means + 95% confidence intervals or as proportions (standard errors). The geometric mean calculated by back transforming the logarithmic means of TG values is presented due to the skewed distribution of TG. Direct age adjustment of the data was conducted using the Korean population 19 years or older in 2010 as the standard population to compare the means of lipid profiles, prevalence of dyslipidemia and rate of use of lipid-lowering medication in Korean adults in each KNHANES. We also assessed trends in lipid profiles in subjects in subgroups of several conventional cardiovascular disease (CVD) risk factors, such as hypertension, diabetes and obesity. The P for trend for mean level of each lipid profile was estimated using a general linear model. Two-sided P-values of ,0.05 were considered statistically significant.
Table 1 Trends in age-adjusted means of lipid profiles for Korean adults in the 2005, 2008 and 2010 KNHANES Men 2005 n
2170
P for trend 2008 2542
2010
Women 2005
2390
3046
P for trend 2008 3624
2010 3237
TC (mg/dl) Overall
185.3 (183.6 –187)
186.9 (185.1 –188.6)
0.026
185.5 (184.1 –186.9)
188.4 (187.1 – 189.8)
188.2 (186.6 – 189.9)
19–40 years
179.7 (176.9 –182.4)
184 (182.3 –185.7)
180.4 (177.8 –183.1)
182.2 (179.5 –184.9)
0.222
169.8 (167.7 –172)
174.3 (172.6 – 176)
173.7 (171.6 – 175.8)
0.006 0.006
40–65 years
187.6 (185.4 –189.8)
190.1 (188– 192.2)
191.9 (189.5 –194.3)
0.009
192.7 (190.6 –194.8)
193.9 (191.7 – 196)
194.5 (192.1 – 197)
0.261
65 years
181.7 (177.7 –185.6)
180.7 (176.6 –184.7)
179.9 (176.5 –183.3)
0.501
198.5 (195.3 –201.7)
201.8 (198.5 – 205.2)
198.6 (195.1 – 202.1)
0.827
HDL-C (mg/dl) Overall 19–40 years
42.5 (42– 43) 43 (42.2 –43.8)
45.5 (45– 46)
45.8 (45.2 –46.3)
,0.001
47 (46.5 – 47.5)
50.7 (50.2 – 51.2)
50.7 (50.3 – 51.2)
,0.001
46.3 (45.6 –47)
46.4 (45.6 –47.2)
,0.001
49 (48.1 – 49.8)
53.6 (52.8 – 54.4)
53.1 (52.3 – 53.9)
,0.001 ,0.001
40–65 years
42.2 (41.5 –42.9)
45.3 (44.6 –46)
45.7 (44.9 –46.6)
,0.001
46.9 (46.2 – 47.5)
50.2 (49.5 – 50.8)
50.7 (50 –51.3)
65 years
43.2 (41.7 –44.6)
44.2 (43.2 –45.1)
44.5 (43.4 –45.6)
0.143
44.4 (43.5 – 45.4)
46.4 (45.6 – 47.3)
46.5 (45.4 – 47.5)
0.003 0.584
LDL-C (mg/dl) 113.7 (112.1 –115.3)
112 (110.5 –113.5)
113 (111.3 –114.7)
0.436
116.1 (114.9 –117.3)
115.7 (114.5 – 116.9)
115.6 (114.3 – 117)
19–40 years
111.1 (108.6 –113.6)
108.2 (105.9 –110.4)
110.1 (107.5 –112.6)
0.437
103.1 (101.4 –104.8)
103.4 (101.9 – 105)
103.1 (101.4 – 104.8)
0.959
40–65 years
115.3 (113.2 –117.5)
115.1 (113.2 –117.1)
115.9 (113.6 –118.2)
0.737
121.9 (120 – 123.8)
120.6 (118.6 – 122.5)
121.5 (119.4 – 123.6)
0.68
65 years
113.5 (109.7 –117.2)
110.8 (107– 114.6)
108.6 (105.3 –111.9)
0.061
127.3 (124.5 –130.1)
127 (124 – 129.9)
123.5 (120.3 – 126.6)
0.092
Overall
123.7 (120.1 –127.4)
122.3 (119.2 –125.4)
122.8 (119.0 –126.7)
0.728
100.1 (98.1 – 102.0)
95.7 (93.9 – 97.5)
95.1 (93.3 – 96.9)
19–40 years
112.7 (107.6 –118)
113.4 (109.2 –117.8)
111.4 (105.7 –117.3)
0.795
80.9 (78.5 – 83.3)
76.5 (74.4 – 78.7)
77.3 (74.8 – 79.9)
40–65 years
135.4 (130.9 –140)
130.6 (126.3 –135.1)
133.1 (128.2 –138.3)
0.452
107.6 (104.3 –110.9)
101.3 (98.2 – 104.5)
98.6 (95.7 – 101.6)
112 (104.2 –120.3)
114.3 (107.9 –121.1)
117.3 (110.1 –125)
0.351
123.3 (118.1 –128.7)
127.2 (122.2 – 132.5)
127.2 (120.8 – 133.8)
Overall
141.5 (139.9 –143.2)
139.8 (138.2 –141.5)
141.1 (139.3 –143)
0.631
138.5 (137.2 –139.8)
137.7 (136.4 – 139)
137.5 (135.9 – 139)
0.307
19–40 years
136.6 (134.1 –139.2)
134.1 (131.5 –136.7)
135.8 (133– 138.5)
0.521
120.9 (119 – 122.8)
120.7 (119.1 – 122.3)
120.6 (118.5 – 122.6)
0.826
TG (mg/dl)
65 years
,0.001 0.024 ,0.001 0.331
Non-HDL-C (mg/dl)
40–65 years
145.4 (143.3 –147.5)
144.8 (142.7 –146.9)
146.2 (143.7 –148.7)
0.686
145.9 (143.9 –147.9)
143.7 (141.6 – 145.8)
143.9 (141.5 – 146.2)
0.163
65 years
138.5 (134.4 –142.6)
136.5 (132.8 –140.2)
135.4 (131.6 –139.2)
0.265
154.1 (151.1 –157.2)
155.4 (152 – 158.8)
152.2 (148.6 – 155.7)
0.483
4.5 (4.45 –4.56)
4.23 (4.18 –4.28)
4.26 (4.19 –4.32)
,0.001
4.09 (4.05 – 4.13)
3.87 (3.84 – 3.91)
3.85 (3.82 – 3.89)
,0.001
4.33 (4.25 –4.41)
4.04 (3.97 –4.12)
4.08 (3.99 –4.17)
,0.001
3.58 (3.52 – 3.63)
3.36 (3.31 – 3.41)
3.38 (3.32 – 3.44)
,0.001 ,0.001
TC/HDL-C Overall 19–40 years 40–65 years
4.62 (4.55 –4.70)
4.35 (4.28 –4.42)
4.37 (4.28 –4.46)
,0.001
65 years
4.43 (4.28 –4.59)
4.25 (4.15 –4.35)
4.23 (4.08 –4.37)
0.047
4.26 (4.2 – 4.32)
4.01 (3.95 – 4.07)
3.96 (3.9 – 4.02)
4.63 (4.53 – 4.73)
4.51 (4.42 – 4.61)
4.45 (4.33 – 4.57)
0.017
LDL-C/HDL-C 2.79 (2.75 –2.84)
2.57 (2.53 –2.61)
2.59 (2.53 –2.64)
,0.001
2.57 (2.54 – 2.60)
2.39 (2.36 – 2.42)
2.38 (2.35 – 2.41)
,0.001
2.69 (2.62 –2.75)
2.43 (2.37 –2.5)
2.48 (2.41 –2.55)
,0.001
2.19 (2.14 – 2.23)
2.01 (1.97 – 2.05)
2.02 (1.98 – 2.07)
,0.001
40–65 years
2.85 (2.79 –2.91)
2.65 (2.59 –2.7)
2.65 (2.58 –2.73)
,0.001
2.7 (2.65 – 2.75)
2.5 (2.45 – 2.55)
2.48 (2.43 – 2.53)
,0.001
Continued
289
Overall 19–40 years
T R E N DS I N L I P I D P RO F I L E S A M O NG S O U T H KO R E A N A D U LTS
Overall
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50 40 30 Overall Men Women
20 10 0 2005
2010 2008 Prevalence of dyslipidemia
(%) 8 6 4 Overall Men Women
2 0
2005 2008 2010 Rates of lipid-lowering medication use
Fig. 1 Trends in age-adjusted prevalence of dyslipidemia and the rates of use of lipid-lowering medication in Korean adults in the 2005, 2008,and 2010 KNHANES. are presented as mean + 95% confidence intervals. The P for trend was estimated using a general linear model.
3.93 (3.78 – 4.09) 0.723 3.85 (3.65 –4.07) 3.77 (3.59 –3.94) 3.79 (3.56 –4.04) 65 years
KNHANES, Korea National Health and Nutrition Examination Survey; TC, total cholesterol; TG, triglycerides; LDL-C, low-density lipoprotein cholesterol; HDL-C, high-density lipoprotein cholesterol. Data
,0.001
0.992 3.93 (3.74 – 4.13)
,0.001
4.08 (3.95 –4.2) 4.4 (4.26 –4.54) 40–65 years
4.12 (3.98 –4.27)
3.45 (3.36 – 3.55)
3.93 (3.79 – 4.07)
3.09 (3.02 – 3.17)
,0.001
0.004
3.18 (3.1 – 3.26)
2.57 (2.5 – 2.64)
3.03 (2.99 – 3.08) 3.06 (3.01 – 3.11)
2.55 (2.49 – 2.61)
3.27 (3.21 – 3.33)
2.75 (2.69 – 2.82)
0.004
0.047
3.89 (3.78 –4.00) 3.87 (3.79 –3.96)
3.62 (3.51 –3.73)
4.10 (3.99 –4.21)
3.79 (3.64 –3.94)
Overall
19–40 years
TG/HDL-C
3.58 (3.43 –3.74)
2.76 (2.67 – 2.85) 2.84 (2.77 – 2.92) 2.98 (2.9 – 3.05) 0.007 2.56 (2.44 –2.68) 2.61 (2.52 –2.71)
2010 2008 2005
2.79 (2.66 –2.92) 65 years
2005
Women P for trend Men
(%) 60
non-HDL-C levels and TC/HDL-C, LDL-C/HDL-C and TG/HDL-C ratios and the age- and sex-adjusted mean HDL-C level increased significantly from 2005 to 2008 and to 2010. Among diabetic subjects not taking lipid-lowering medication, there were also decreasing trends in age- and sexadjusted mean non-HDL-C level and TC/HDL-C and LDL-C/HDL-C ratios, and age- and sex-adjusted mean HDL-C levels increased linearly over the study period. In the obesity group, there were linearly decreasing trends in age- and sex-adjusted geometric means of TG and TG/ HDL-C ratio and means of TC/HDL-C and LDL-C/ HDL-C ratios. Age- and sex-adjusted mean TC and HDL-C levels increased linearly within the group. Similar trends over this period occurred in obese subjects who did not use lipid-lowering medication.
Discussion Main findings of this study
From 2005 to 2008 and to 2010, there was a declining trend in the prevalence of dyslipidemia, and the rates of use of lipid-lowering medication increased linearly for Korean adults overall, for men and for women. Slightly increasing trends in the age-adjusted mean TC level were observed in both Korean men and women. However, the mean TC level has continued to be ,200 mg/dl in both sexes. The age-adjusted
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2008
2010
,0.001
P for trend
J O U RN A L O F P U B LI C H E A LT H
Table 1 Continued
290
T R E N DS I N L I P I D P RO F I L E S A M O NG S O U T H KO R E A N A D U LTS
291
Table 2 Trends in age- and sex-adjusted mean lipid profiles in subjects not taking lipid-lowering medication in the 2005, 2008 and 2010 KNHANES 2005 n
5148
2008
2010
P for trend
5983
5330
187.3 (186.1 –188.6)
188.5 (187.2 –189.8)
,0.001
45.2 (44.8 –45.5)
48.5 (48.1 –48.9)
48.7 (48.3 –49.1)
,0.001
LDL-C (mg/dl)
115.3 (114.3 –116.3)
114.5 (113.4 –115.5)
115.5 (114.3 –116.6)
0.958
TG (mg/dl)
108.9 (106.8 –111)
105.7 (103.9 –107.5)
105.3 (103.3 –107.3)
0.012
Non-HDL-C (mg/dl)
139.8 (138.5 –141.1)
TC (mg/dl)
185 (183.8 –186.2)
HDL-C (mg/dl)
139.9 (138.8 –141)
138.9 (137.7 –140)
TC/HDL-C
4.27 (4.23 –4.3)
4.03 (3.99 –4.07)
4.04 (4– 4.08)
,0.001
LDL-C/HDL-C
2.67 (2.64 –2.69)
2.47 (2.44 –2.5)
2.48 (2.45 –2.52)
,0.001
3.6 (3.54 –3.66)
3.38 (3.34 –3.43)
3.37 (3.32 –3.42)
,0.001
TG/HDL-C
0.802
HDL-C, high-density lipoprotein cholesterol. Data are presented as mean + 95% confidence intervals. The P for trend was estimated using a general linear model.
mean HDL-C level increased linearly in both Korean men and women during the same period. There were no significant changes in age-adjusted mean LDL-C level in both sexes, and the level was slightly .100 mg/dl over the 6-year study period. The age-adjusted geometric mean TG level did not change in men but was in a declining trend for women. There were significantly decreasing trends in age-adjusted mean lipid-related ratios in both men and women. In addition, similar patterns in the age- and sex-adjusted mean TC and HDL-C levels and lipid ratios were observed in Korean adults not taking lipid-lowering medication. The favorable trends were also observed in subjects with hypertension, diabetes or obesity irrespective of the lipid-lowering medication use. What is already known on this topic
Declines in TC and LDL-C levels have been recently noted in developed countries such as North America, Western countries and Australasia.20,21 In the USA between 1988 and 2010, although the age-adjusted mean TC, LDL-C, TG and non-HDL-C levels were still higher than those in South Korea, the mean TC, LDL-C and non-HDL-C levels decreased and the mean HDL-C level increased linearly. In addition, the trends among American adults not receiving lipid-lowering medication were similar to those for adults overall.22 The continuously ongoing efforts to lower cholesterol levels in the USA made these favorable trends in lipids and lipoproteins and decreased the risk of CVD. Among Korean adults, hypo-HDL-cholesterolemia and hypertriglyceridemia were previously reported as dominant subtypes of dyslipidemia and were considered to be caused by a carbohydrate-centered diet and correlated with an increased prevalence of obesity and diabetes.16,23,24
What this study adds
Compared with a previous study, notable changes in lipid profiles for Korean adults over this period were favorable trends in HDL-C level and lipid ratios and lowered TG level in women. The changes in HDL-C levels observed in this study may be more attributable to changes in lifestyle than an increasing tendency to use lipid-lowering medication given that similar trends continued in those who did not use lipidlowering medication. In addition to genetic factors, various environmental factors such as alcohol consumption, cigarette smoking, physical activity and dietary components are determinants of HDL-C level. Studies have shown that moderate alcohol consumption increases and cigarette smoking decreases HDL-C levels.25,26 Increased physical activity is known to be associated with higher HDL-C level.26 A moderate-fat diet in comparison with a low-fat diet has been shown to raise the serum HDL-C level, and a polyunsaturated fat-rich diet or a low-glycemic-index carbohydrate diet may also improve the HDL-C profile.26,27 The rate of current smoking in Korean men decreased from 51.6% in 2005 to 48.3% in 2010. The drinking rate for a month showed increasing tendency in both sexes, but high-risk alcohol drinking rate did not show linear changes in the same period. The proportions of total fat or carbohydrate intakes of total calories in Korean adults were not changed significantly within the period. The rate of physical activity with more than moderate degree showed decreasing trends in the period.28 In light of declining trends in mean lipid-related ratios, favorable lifestyle changes such as decreased current smoking rate appear to be more contributable to increasing trend in HDL-C level because undesirable lifestyle changes such as increased drinking rate or decreased physical activity can also elevate the TC, LDL-C and TG levels.
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KNHANES, Korea National Health and Nutrition Examination Survey; TC, total cholesterol; TG, triglycerides; LDL-C, low-density lipoprotein cholesterol;
292
n
TC
HDL-C
LDL-C
TG
Non-HDL-C
TC/HDL-C
LDL-C/HDL-C
TG/HDL-C
Subjects with hypertension 2005 1277
193.2 (191.1 – 195.2)
2008 1601
195 (192.6 – 197.4)
2010 1822
193.9 (191.7 – 196.1)
P for trend
0.618
43.6 (42.9 – 44.2) 119.6 (117.7 –121.5) 135.4 (131 –140) 46.7 (46 –47.4)
149.6 (147.6 –151.6)
4.61 (4.54 –4.68)
2.86 (2.81 – 2.91)
118.9 (116.7 –121.1) 129.8 (125.5 – 134.2) 148.3 (145.9 –150.6)
4.35 (4.28 –4.42)
2.66 (2.6 – 2.72)
46.5 (45.9 – 47.2) 117.5 (115.5 –119.5) 131.9 (128.3 – 135.5) 147.3 (145.2 –149.4) ,0.001
0.14
0.205
0.121
4.32 (4.26 –4.39) ,0.001
2.62 (2.57 – 2.67) ,0.001
4.3 (4.17 – 4.44) 3.98 (3.87 – 4.1) 4.04 (3.95 – 4.14) 0.002
Hypertensive subjects who did not use lipid-lowering medication 2005 1230
193.1 (191 –195.2)
43.5 (42.8 – 44.2) 119.4 (117.5 –121.4) 135.8 (131.3 – 140.4) 149.6 (147.6 –151.6)
4.62 (4.55 –4.69)
2.86 (2.81 – 2.91)
4.32 (4.18 – 4.46)
2008 1464
196.2 (193.7 – 198.8)
46.5 (45.8 – 47.3) 120.3 (118.1 –122.5)
4.39 (4.32 –4.46)
2.7 (2.64 – 2.76)
3.99 (3.88 – 4.12)
2010 1600
195.8 (193.5 – 198.1)
P for trend
0.072
46.3 (45.6 – 47) ,0.001
130 (125.6 – 134.5) 149.7 (147.3 –152.1)
119.6 (117.6 –121.7) 132.3 (128.4 – 136.3) 149.5 (147.3 –151.7) 0.859
0.218
0.964
4.39 (4.33 –4.46) ,0.001
2.69 (2.63 – 2.74) ,0.001
4.06 (3.96 – 4.18) 0.003
Subjects with diabetes 2005
416
193 (188.9 – 197.2)
4.8 (4.67 –4.93)
2.99 (2.88 – 3.09)
4.62 (4.41 – 4.84)
2008
583
191.7 (187.9 – 195.5)
43.6 (42.8 – 44.5)
117 (113.8 –120.3) 137.7 (130.9 – 145)
148.1 (144.5 –151.7)
4.54 (4.44 –4.64)
2.78 (2.69 – 2.86)
4.35 (4.17 – 4.54)
2010
528
186.8 (183.2 – 190.4)
44.5 (43.3 – 45.7) 111.1 (107.4 –114.8) 137.6 (130 –145.6)
142.3 (138.5 –146.2)
4.37 (4.23 –4.51)
2.60 (2.48 – 2.72)
P for trend
0.033
41.7 (40.7 – 42.7) 119.9 (116 – 123.7)
,0.001
0.002
143.4 (136.4 – 150.7) 151.4 (147.3 –155.5)
0.268
0.002
,0.001
,0.001
4.32 (4.11 – 4.54) 0.045
Diabetic subjects who did not use lipid-lowering medication 2005
394
193.8 (189.5 – 198.1)
41.8 (40.7 – 42.8) 120.3 (116.2 –124.4) 143.9 (136.5 – 151.8)
152 (147.7 –156.2)
4.81 (4.67 –4.94)
2.99 (2.88 – 3.1)
4.63 (4.4 – 4.86)
2008
528
192.1 (187.9 – 196.3)
43.1 (42.2 – 44)
149 (145 – 152.9)
4.59 (4.49 –4.69)
2.82 (2.74 – 2.91)
4.38 (4.19 – 4.58)
2010
428
190.1 (185.9 – 194.2)
44.6 (43.3 – 45.9) 114.6 (110.4 –118.8) 137.2 (128.3 – 146.8) 145.5 (140.9 –150)
4.45 (4.28 –4.62)
2.69 (2.55 – 2.83)
P for trend
0.236
0.001
117.9 (114.4 –121.5) 137.7 (130.5 – 145.3) 0.061
0.239
0.042
,0.001
,0.001
4.31 (4.05 – 4.57) 0.058
Subjects with obesity 2005 3539
181 (179.6 – 182.4)
46.4 (46 –46.8)
2008 4238
183 (181.7 – 184.3)
49.7 (49.3 – 50.2) 111.1 (109.9 –112.2)
112.2 (111 – 113.4)
2010 3879
183.6 (182.4 – 284.9)
P for trend
0.005
50.2 (49.7 – 50.6) 111.5 (110.3 –112.6) ,0.001
0.326
100 (97.8 –102.2)
134.6 (133.3 –135.8)
4.06 (4.02 –4.09)
2.53 (2.5 – 2.56)
3.31 (3.25 – 3.37)
96.8 (95.2 –98.5)
133.3 (132 – 134.6)
3.84 (3.8– 3.87)
2.34 (2.31 – 2.37)
3.12 (3.07 – 3.16)
95.4 (93.3 –97.6)
133.5 (132.2 –134.7)
0.004
0.184
3.81 (3.77 –3.85) ,0.001
2.33 (2.3 – 2.36) ,0.001
3.07 (3.01 – 3.13) ,0.001
Obese subjects who did not use lipid-lowering medication 2005 3509
180.8 (179.4 – 182.2)
46.1 (45.7 – 46.6) 112.1 (110.8 –113.3) 101.1 (98.8 –103.4)
134.7 (133.4 –136)
4.08 (4.04 –4.11)
2.54 (2.51 – 2.57)
3.34 (3.28 – 3.41)
2008 4142
182.9 (181.5 – 184.2)
49.4 (48.9 – 49.9) 111.1 (109.9 –112.2)
97.7 (96 –99.4)
133.5 (132.2 –134.7)
3.86 (3.82 –3.9)
2.36 (2.33 – 2.39)
3.15 (3.1 – 3.2)
96.2 (93.8 –98.5)
134.1 (132.8 –135.4)
2010 3721 P for trend
184 (182.7 – 185.3) ,0.001
49.9 (49.4 – 50.4) 111.9 (110.8 –113.1) ,0.001
0.751
0.003
0.435
3.84 (3.8– 3.89) ,0.001
2.35 (2.32 – 2.39) ,0.001
3.1 (3.03 – 3.16) ,0.001
TC, total cholesterol; TG, triglycerides; LDL-C, low-density lipoprotein cholesterol; HDL-C, high-density lipoprotein cholesterol. Data are presented as mean + 95% confidence intervals. The P for trend was estimated using a general linear model.
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Table 3 Trends in age- and sex-adjusted mean lipid profiles according to use of lipid-lowering medication in the subgroups of hypertension, diabetes and obesity
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Limitations of this study
The present study has several limitations. Our analysis was based on data from 3 years of the KNHANES over a 6-year period. The specific types of lipid-lowering medication could not be investigated because only self-reported data for use of any lipid-lowering medication were collected. We could not consider the effect of genetic factors on lipid profiles, and we had limited data for the impact of lifestyle factors on the lipid profiles in the same survey period. Despite these limitations, as nationally representative data, the KNHANES enables us to evaluate the accurate health status of contemporary Koreans as a single ethnicity. Further data from following surveys are needed to confirm these trends, and further research is warranted to investigate simultaneously the effects of various lifestyle factors.
Conclusion Based on data from the 2005, 2008 and 2010 KNHANES, there was a decrease in the prevalence of dyslipidemia and an increase in the use of lipid-lowering medication in Korean adults. Favorable trends in HDL-C level and lipid-related ratios in both men and women and in TG level in women were observed among South Korean population, and these trends were consistent even in subjects who were not treated with lipid-lowering medication. Although favorable trends were also observed in subjects with hypertension, diabetes or obesity, not all of the lipid profiles showed a favorable tendency in these subgroups. These findings suggest that more intense strategies are needed to control dyslipidemia and prevent future cardiovascular risk.
Supplementary data Supplementary data are available at the Journal of Public Health online.
Funding None.
References 1 Yan-Ling Z, Dong-Qing Z, Chang-Quan H et al. Cigarette smoking and its association with serum lipid/lipoprotein among Chinese nonagenarians/centenarians. Lipids Health Dis 2012;11:94. 2 Rana JS, Boekholdt SM, Kastelein JJ et al. The role of non-HDL cholesterol in risk stratification for coronary artery disease. Curr Atheroscler Rep 2012;14(2):130 – 4. 3 Ridker PM, Rifai N, Cook NR et al. Non-HDL cholesterol, apolipoproteins A-I and B100, standard lipid measures, lipid ratios, and CRP as risk factors for cardiovascular disease in women. JAMA 2005;294(3):326– 33. 4 Shai I, Rimm EB, Hankinson SE et al. Multivariate assessment of lipid parameters as predictors of coronary heart disease among postmenopausal women: potential implications for clinical guidelines. Circulation 2004;110(18):2824 – 30. 5 Toth PP. Subclinical atherosclerosis: what it is, what it means and what we can do about it. Int J Clin Pract 2008;62(8):1246 – 54. 6 The Lipid Research Clinics Coronary Primary Prevention Trial results. I. Reduction in incidence of coronary heart disease. JAMA 1984;251(3):351– 64. 7 The Lipid Research Clinics Coronary Primary Prevention Trial results. II. The relationship of reduction in incidence of coronary heart disease to cholesterol lowering. JAMA 1984;251(3):365– 74. 8 Grover SA, Abrahamowicz M, Joseph L et al. The benefits of treating hyperlipidemia to prevent coronary heart disease. Estimating changes in life expectancy and morbidity. JAMA 1992;267(6):816 – 22.
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Another noteworthy point from the present study was the improving trend in the TG level in female subjects over the survey years. Both overall and abdominal adiposity are strongly associated with hypertriglyceridemia,23 and the trend in the TG level correlates with the secular trend in the prevalence of obesity in Korean women, which decreased in the youngerand middle-aged subgroups but increased in the older subgroup. These trends seem to be influenced by the increased participation of Korean women in socioeconomic activity, the consequent rise in age at marriage and a lowered birth rate, and the social preference for thin women.29 Additionally, the mean TC, LDL-C, TG and non-HDL-C levels and lipid ratios in women older than 65 years of age were higher than those in men of the same age. The possible cause is thought to be caused by hormonal effects. Premenopausal women have lower lipid levels than men of the same age but lipid levels in postmenopausal women increase and become higher than those of men.24 Meanwhile, there were also favorable trends in some lipid profiles in subgroups of subjects, such as those with hypertension, diabetes and obesity. These patterns persisted among subjects who did not take lipid-lowering medication in each subgroup. All of the trends in each subgroup are consistent with the improvement in awareness and control rate of cardiovascular risk factors from 1998 to 2007 in South Korea.30 However, control remains inadequate, especially in diabetic patients, who had an LDL-C level .100 mg/dl. Hypertension, diabetes and obesity are substantial risk factors for CHD, and they enhance the morbidity and mortality of CVD with uncontrolled dyslipidemia.31,32 Therefore, serum lipid and lipoprotein levels in subjects with diabetes and hypertension should be controlled strictly to prevent macrovascular or microvascular complications.33,34
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9 Okamura T. Dyslipidemia and cardiovascular disease: a series of epidemiologic studies in Japanese populations. J Epidemiol 2010;20(4): 259 – 65. 10 Murray CJ, Lopez AD. Mortality by cause for eight regions of the world: Global Burden of Disease Study. Lancet 1997;349(9061): 1269 – 76. 11 Lopez AD. Assessing the burden of mortality from cardiovascular diseases. World Health Stat Q 1993;46(2):91– 6. 12 Sekikawa A, Kuller LH, Ueshima H et al. Coronary heart disease mortality trends in men in the post World War II birth cohorts aged 35 – 44 in Japan, South Korea and Taiwan compared with the United States. Int J Epidemiol 1999;28(6):1044 – 9.
14 Chang HS, Kim HJ, Nam CM et al. The socioeconomic burden of coronary heart disease in Korea. J Prev Med Public Health 2012; 45(5):291 –300. 15 Kang HY, Lim SJ, Suh HS et al. Estimating the lifetime economic burden of stroke according to the age of onset in South Korea: a cost of illness study. BMC Public Health 2011;11:646. 16 Lee MH, Kim HC, Ahn SV et al. Prevalence of dyslipidemia among Korean adults: Korea National Health and Nutrition Survey 1998 – 2005. Diabetes Metab J 2012;36(1):43– 55. 17 Executive Summary of the Third Report of The National Cholesterol Education Program (NCEP). Expert panel on detection, evaluation, and treatment of high blood cholesterol in adults (Adult Treatment Panel III). JAMA 2001;285(19):2486 – 97. 18 Oh SW, Shin SA, Yun YH et al. Cut-off point of BMI and obesity-related comorbidities and mortality in middle-aged Koreans. Obes Res 2004;12(12):2031– 40. 19 Weisell RC. Body mass index as an indicator of obesity. Asia Pac J Clin Nutr 2002;11(Suppl 8):S681 – 4. 20 Ferrieres J, Bongard V, Dallongeville J et al. Trends in plasma lipids, lipoproteins and dyslipidaemias in French adults, 1996 –2007. Arch Cardiovasc Dis 2009;102(4):293 – 301. 21 Farzadfar F, Finucane MM, Danaei G et al. National, regional, and global trends in serum total cholesterol since 1980: systematic analysis of health examination surveys and epidemiological studies with 321 country-years and 3.0 million participants. Lancet 2011;377(9765): 578 – 86.
23 Kim SM, Han JH, Park HS. Prevalence of low HDL-cholesterol levels and associated factors among Koreans. Circ J 2006;70(7): 820 – 6. 24 Song Y, Joung H. A traditional Korean dietary pattern and metabolic syndrome abnormalities. Nutr Metab Cardiovasc Dis 2012;22(5):456–62. 25 Brinton EA, Nanjee MN. Effects of Ethanol Intake on High Density Lipoprotein Metabolism in Humans. High Density Lipoproteins, Dyslipidemia, and Coronary Heart Disease 2010;129 – 38. 26 Mureddu GF, Brandimarte F, De Luca L. High-density lipoprotein levels and risk of cardiovascular events: a review. J Cardiovasc Med (Hagerstown) 2012;13(9):575– 86. 27 Baum SJ, Kris-Etherton PM, Willett WC et al. Fatty acids in cardiovascular health and disease: a comprehensive update. J Clin Lipidol 2012;6(3):216 – 34. 28 Korea Centers for Disease Control and Prevention. Korea Health Statistics 2010: Korea National Health and Nutrition Examination Survey (KNHANES V-1). http://knhanes.cdc.go.kr/knhanes/index. do (10 July 2013, date last accessed). 29 Wolf G. High-fat, high-cholesterol diet raises plasma HDL cholesterol: studies on the mechanism of this effect. Nutr Rev 1996;54 (1 Pt 1):34– 5. 30 Lee K. Cardiovascular risk prevalence, awareness, treatment, and control from 1998 to 2007 in Koreans. Asia Pac J Clin Nutr 2010; 19(2):261– 5. 31 Simons LA, Simons J, Friedlander Y et al. Is prediction of cardiovascular disease and all-cause mortality genuinely driven by the metabolic syndrome, and independently from its component variables? The Dubbo study. Heart Lung Circ 2011;20(4):214– 9. 32 Matikainen N, Taskinen MR. Management of dyslipidemias in the presence of the metabolic syndrome or type 2 diabetes. Curr Cardiol Rep 2012;14(6):721 – 31. 33 Raikou M, McGuire A, Colhoun HM et al. Cost-effectiveness of primary prevention of cardiovascular disease with atorvastatin in type 2 diabetes: results from the Collaborative Atorvastatin Diabetes Study (CARDS). Diabetologia 2007;50(4):733 –40. 34 Colhoun HM, Betteridge DJ, Durrington PN et al. Primary prevention of cardiovascular disease with atorvastatin in type 2 diabetes in the Collaborative Atorvastatin Diabetes Study (CARDS): multicentre randomised placebo-controlled trial. Lancet 2004;364(9435):685 – 96.
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13 Khang YH, Lynch JW, Kaplan GA. Impact of economic crisis on cause-specific mortality in South Korea. Int J Epidemiol 2005;34(6): 1291 – 301.
22 Carroll MD, Kit BK, Lacher DA et al. Trends in lipids and lipoproteins in US adults, 1988 – 2010. JAMA 2012;308(15):1545 – 54.
Trends in lipid profiles among South Korean adults: 2005, 2008 and 2010 Korea National Health and Nutrition Examination Survey Ga Eun Nam1, Kyungdo Han2, Yong Gyu Park2, Youn Seon Choi1, Seon Mee Kim1, Sang-Yhun Ju3, Byung-Joon Ko1, Yang Hyun Kim1, Eun Hye Kim1, Kyung Hwan Cho1, Do Hoon Kim1 1
Department of Family Medicine, Korea University College of Medicine, Seoul, South Korea Department of Biostatistics, Catholic University College of Medicine, Seoul, South Korea 3 Department of Family Medicine, Yeouido St. Mary’s Hospital, College of Medicine, Catholic University of Korea, Seoul, South Korea Address correspondence to Do Hoon Kim, E-mail: [email protected]; Kyung Hwan Cho, E-mail: [email protected] 2
Background This study aimed to investigate recent trends in the prevalence and parameters of dyslipidemia and rates of lipid-lowering medication use in Korean adults. Trends in lipid profiles in subjects with hypertension, diabetes or obesity were also studied. Methods Data from the Korea National Health and Nutrition Examination Survey in 2005, 2008 and 2010 were used in this study. A total of 17 009 subjects participated in this study. Results There was a declining trend in the prevalence of dyslipidemia and an increasing trend in the rates of use of lipid-lowering medication among Korean adults. In both men and women, the age-adjusted mean high-density lipoprotein cholesterol level linearly increased. There was a significantly decreasing trend in the age-adjusted mean triglycerides in women and age-adjusted mean lipid-related ratios in both sexes. The ageadjusted mean total cholesterol level showed a slightly increasing trend and the age-adjusted mean low-density lipoprotein cholesterol level was not changed in both sexes. These patterns persisted among subjects not taking lipid-lowering medication. The favorable trends were also observed in subjects with hypertension, diabetes and obesity. Conclusions Our study showed favorable trends in the prevalence of dyslipidemia and in several lipid profiles among Korean adults. Keywords cardiovascular risk, cholesterol, dyslipidemia, lipid, lipoprotein, trends
Introduction Dyslipidemia is generally defined as an increased level of total cholesterol (TC), triglycerides (TG) and low-density lipoprotein cholesterol (LDL-C) and a decreased level of high-density lipoprotein cholesterol (HDL-C).1 Several recent studies have shown that non-HDL-C level and lipid-related ratios are more susceptible in reflecting the severity and morbidity of coronary heart disease (CHD) than individual lipid and lipoprotein levels. Therefore, they are more meaningful than each lipid level in diagnosis and early prevention of CHD.2 – 4 However, little is known about the trends in non-HDL-C and lipid ratio levels among South Korean population.
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Ga Eun Nam, Clinical Instructor of Family Medicine Kyungdo Han, Researcher of Biostatistics Yong Gyu Park, Professor of Biostatistics Youn Seon Choi, Professor of Family Medicine Seon Mee Kim, Professor of Family Medicine Sang-Yhun Ju, Clinical Assistant Professor of Family Medicine Byung-Joon Ko, Clinical Assistant Professor of Family Medicine Yang Hyun Kim, Clinical Assistant Professor of Family Medicine Eun Hye Kim, Clinical Instructor of Family Medicine Kyung Hwan Cho, Professor of Family Medicine Do Hoon Kim, Professor of Family Medicine
# The Author 2014. Published by Oxford University Press on behalf of Faculty of Public Health. All rights reserved. For permissions, please e-mail: [email protected].
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A B S T R AC T
T R E N DS I N L I P I D P RO F I L E S A M O NG S O U T H KO R E A N A D U LTS
Methods Survey overview and study subjects
The present study was based on data obtained from the KNHANES in 2005, 2008 and 2010. The KNHANES has been conducted periodically by the Division of Chronic Disease Surveillance of the Korea Centers for Disease Control and Prevention (KCDC) since 1998. It is a nationwide survey designed to assess national health and nutrition levels accurately and consists of a health interview survey, a nutrition survey and a health examination survey. This survey selected participants from sampling household units defined on the basis of household registries using a stratified, multistage and probability sampling design with proportional allocation. Of the 10 816 people who participated in the 2005 survey, complete data were obtained from 7597 subjects (70.2%). Likewise, 9744 (77.8%) of 12 528 subjects in 2008 and 8518 (80.4%) of 10 589 subjects in 2010 participated in the survey. We then excluded subjects younger than 19 years of age, subjects with any missing data on lipid profiles and subjects who did not fast for at least 8 h before blood sampling. Finally, data on 5216 subjects from the 2005 survey, 6166 subjects from the 2008 survey and 5627 subjects from the 2010
survey were used in the analyses. All of the study participants provided written informed consent, and the institutional review board of the KCDC approved the study protocol. Anthropometric and laboratory measurements
Trained staff performed a physical examination following standard procedures. Body weight and height were measured to the nearest 0.1 kg and 0.1 cm, respectively, while the subjects were wearing light clothing but no shoes. Body mass index (BMI) was calculated as weight in kilograms divided by the square of the height in meters. Systolic blood pressure and diastolic blood pressure were measured using a standard mercury sphygmomanometer. Blood samples were taken after the subjects fasted for 8 or more hours. The samples were immediately centrifuged and refrigerated and then transported in cold storage to the Central Testing Institute in Seoul, Korea and analyzed within 24 h. The serum levels of TC, HDL-C, TG and fasting plasma glucose were measured enzymatically using an Advia 1650/2400 (Siemens, New York, NY, USA) in the 2005 survey and a Hitachi Automatic Analyzer 7600 (Hitachi, Tokyo, Japan) in the 2008 and 2010 surveys. LDL-C level was calculated using Friedewald’s equation for subjects with serum TG levels ,400 mg/dl and was measured directly using commercially available kits (Cholestestw LDL, Sekisui Medical, Tokyo, Japan) when TG levels were 400 mg/dl. Non-HDL-C was calculated as serum TC level minus HDL-C level. Definition of dyslipidemia, hypertension, diabetes and obesity
According to the criteria of the National Cholesterol Education Program Adult Treatment Panel III, dyslipidemia was diagnosed when participants met one or more of the following criteria: (i) TC level 240 mg/dl on the blood test after fasting, (ii) HDL-C level ,40 mg/dl, (iii) LDL-C level 160 mg/dl, (iv) TG level 200 mg/dl and (v) the use of lipid-lowering medication or diagnosis of dyslipidemia by a physician.17 Hypertension was defined by blood pressure 140/ 90 mmHg or treatment with antihypertensive medication. Diabetes was defined by fasting plasma glucose level 126 mg/dl, current use of insulin or oral hypoglycemic agents, or diagnosis by a physician. We defined obesity as a BMI 25 kg/m2.18,19 Statistical analyses
Statistical analyses were conducted using the SAS survey procedure (version 9.2; SAS Institute, Cary, NC, USA) to reflect
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Dyslipidemia is one of the most important risk factors for CHD and stroke. Many prior studies have demonstrated that morbidity and mortality from these diseases can be reduced by lowering the blood cholesterol level.5 – 10 Although mortality from CHD has decreased in developed countries, it has been rapidly rising in developing countries such as South Korea, China and other Asian countries over recent decades.11,12 CHD is now one of the leading causes of death, and the age at onset of CHD or stroke has been reported to be decreasing in South Korea, resulting in a higher lifetime disease burden. Therefore, more effective strategies are needed for prevention of CHD and stroke.13 – 15 In South Korea, the prevalence of dyslipidemia in adults has continuously increased from 32.4% in 1998 to 44.1% in 2005.16 However, there have been no subsequent updates of the prevalence of dyslipidemia and trends in lipid profiles, including the aforementioned novel parameters of dyslipidemia. Therefore, this study aimed to investigate recent trends in lipid profiles including lipid ratios and the prevalence of dyslipidemia in Korean adults based on nationally representative data from the 2005, 2008 and 2010 Korea National Health and Nutrition Examination Survey (KNHANES). We also examined trends in rates of use of lipid-lowering medication and trends in lipid profiles in subjects not treated with lipid-lowering medication. Additionally, trends in lipid profiles in Korean adults with hypertension, diabetes or obesity were studied.
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Trends in the prevalence of dyslipidemia
The trends in the prevalence of dyslipidemia in Korean adults between 2005 and 2010 are presented in Fig. 1. The prevalence of dyslipidemia decreased from 44.7% in 2005 to 41.3% in 2010 (P for trend ,0.001), and these trends persisted in both sex groups. The prevalence declined linearly from 53.4% in 2005 to 50% in 2010 in men (P for trend ,0.001) and from 36.1% in 2005 to 32.5% in 2010 in women (P for trend ¼ 0.002). Additional information on the prevalence of dyslipidemia by age group is shown in Supplementary data, Table S1; the prevalence of dyslipidemia appears to be in a declining trend, particularly in younger-aged men and youngerand middle-aged women. Trends in the use of lipid-lowering medication
Figure 1 also shows trends in the use of lipid-lowering medication. The overall proportion of subjects treated with lipid-lowering medication increased linearly from 1.36% in 2005 to 2.92% in 2008 and to 5.34% in 2010 (P for trend ,0.001). These trends continued in both men and women (P for trend ,0.001).
Results Trends in lipid profiles
Table 1 presents the trends in age-adjusted means of lipid profiles for Korean adults according to sex and age. The age-adjusted mean TC level for both men and women increased linearly from 2005 to 2008 and to 2010 (P for trend ¼ 0.026 for men and 0.006 for women). Statistically significant increasing trends in age-adjusted mean TC levels were observed in men aged 40–65 years (P for trend ¼ 0.009) and in women aged 19–40 years (P for trend ¼ 0.006). The age-adjusted mean HDL-C level increased linearly in both men and women between 2005 and 2010 (P for trend ,0.001). Increasing linear trends in age-adjusted mean HDL-C levels were observed in young- and middle-age groups in men and all age groups in women. The age-adjusted geometric mean TG level for men did not change significantly in any age group. However, in women, declining trends in the age-adjusted mean TG level were observed (P for trend ,0.001). Young- and middle-aged women had significantly decreasing geometric means of TG level during this period (P for trend ¼ 0.024 and ,0.001, respectively). As for lipid ratios, the age-adjusted mean ratios of TC/HDL-C and LDL-C/HDL-C showed decreasing trends in all age groups for both sexes. The geometric mean TG/ HDL-C ratios also showed decreasing trends in both men and women, and the trends persisted in the younger- and middleage groups for both sexes. From 2005 to 2010, the age-adjusted mean levels of LDL-C and non-HDL-C showed no significant changes in all age groups for both sexes.
Trends in lipid profiles in subjects not taking lipid-lowering medication
Table 2 shows trends in age- and sex-adjusted mean levels of lipid profiles among subjects not treated with lipid-lowering medication. The age- and sex-adjusted mean HDL-C level increased linearly across the survey years (P for trend ,0.001). Age- and sex-adjusted geometric mean TG and TG/HDL-C levels and means of TC/HDL-C and LDL-C/HDL-C ratios showed significantly declining trends. However, there was an increasing trend for age- and sex-adjusted mean TC levels in these subjects. Trends in lipid profiles according to use of lipid-lowering medication in subgroups with hypertension, diabetes and obesity
Table 3 shows trends in mean levels of lipid profiles according to use of lipid-lowering medication in subgroups with conventional CVD risk factors such as hypertension, diabetes and obesity. Among hypertensive subjects, the age- and sexadjusted mean HDL-C level significantly increased linearly and the age- and sex-adjusted mean TC/HDL-C, LDL-C/ HDL-C and geometric mean TG/HDL-C ratios decreased linearly across the survey years. Similar trends were observed in hypertensive subjects who did not use lipid-lowering medication. In subjects with diabetes, there were linearly decreasing trends in age- and sex-adjusted mean TC, LDL-C and
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the complex sampling design and sampling weights of KNHANES and to provide a nationally representative estimate of prevalence. Mean levels of TC, HDL-C, LDL-C, non-HDL-C level and lipid ratios, and the proportions of dyslipidemia and treatment with lipid-lowering medication are presented as least square means + 95% confidence intervals or as proportions (standard errors). The geometric mean calculated by back transforming the logarithmic means of TG values is presented due to the skewed distribution of TG. Direct age adjustment of the data was conducted using the Korean population 19 years or older in 2010 as the standard population to compare the means of lipid profiles, prevalence of dyslipidemia and rate of use of lipid-lowering medication in Korean adults in each KNHANES. We also assessed trends in lipid profiles in subjects in subgroups of several conventional cardiovascular disease (CVD) risk factors, such as hypertension, diabetes and obesity. The P for trend for mean level of each lipid profile was estimated using a general linear model. Two-sided P-values of ,0.05 were considered statistically significant.
Table 1 Trends in age-adjusted means of lipid profiles for Korean adults in the 2005, 2008 and 2010 KNHANES Men 2005 n
2170
P for trend 2008 2542
2010
Women 2005
2390
3046
P for trend 2008 3624
2010 3237
TC (mg/dl) Overall
185.3 (183.6 –187)
186.9 (185.1 –188.6)
0.026
185.5 (184.1 –186.9)
188.4 (187.1 – 189.8)
188.2 (186.6 – 189.9)
19–40 years
179.7 (176.9 –182.4)
184 (182.3 –185.7)
180.4 (177.8 –183.1)
182.2 (179.5 –184.9)
0.222
169.8 (167.7 –172)
174.3 (172.6 – 176)
173.7 (171.6 – 175.8)
0.006 0.006
40–65 years
187.6 (185.4 –189.8)
190.1 (188– 192.2)
191.9 (189.5 –194.3)
0.009
192.7 (190.6 –194.8)
193.9 (191.7 – 196)
194.5 (192.1 – 197)
0.261
65 years
181.7 (177.7 –185.6)
180.7 (176.6 –184.7)
179.9 (176.5 –183.3)
0.501
198.5 (195.3 –201.7)
201.8 (198.5 – 205.2)
198.6 (195.1 – 202.1)
0.827
HDL-C (mg/dl) Overall 19–40 years
42.5 (42– 43) 43 (42.2 –43.8)
45.5 (45– 46)
45.8 (45.2 –46.3)
,0.001
47 (46.5 – 47.5)
50.7 (50.2 – 51.2)
50.7 (50.3 – 51.2)
,0.001
46.3 (45.6 –47)
46.4 (45.6 –47.2)
,0.001
49 (48.1 – 49.8)
53.6 (52.8 – 54.4)
53.1 (52.3 – 53.9)
,0.001 ,0.001
40–65 years
42.2 (41.5 –42.9)
45.3 (44.6 –46)
45.7 (44.9 –46.6)
,0.001
46.9 (46.2 – 47.5)
50.2 (49.5 – 50.8)
50.7 (50 –51.3)
65 years
43.2 (41.7 –44.6)
44.2 (43.2 –45.1)
44.5 (43.4 –45.6)
0.143
44.4 (43.5 – 45.4)
46.4 (45.6 – 47.3)
46.5 (45.4 – 47.5)
0.003 0.584
LDL-C (mg/dl) 113.7 (112.1 –115.3)
112 (110.5 –113.5)
113 (111.3 –114.7)
0.436
116.1 (114.9 –117.3)
115.7 (114.5 – 116.9)
115.6 (114.3 – 117)
19–40 years
111.1 (108.6 –113.6)
108.2 (105.9 –110.4)
110.1 (107.5 –112.6)
0.437
103.1 (101.4 –104.8)
103.4 (101.9 – 105)
103.1 (101.4 – 104.8)
0.959
40–65 years
115.3 (113.2 –117.5)
115.1 (113.2 –117.1)
115.9 (113.6 –118.2)
0.737
121.9 (120 – 123.8)
120.6 (118.6 – 122.5)
121.5 (119.4 – 123.6)
0.68
65 years
113.5 (109.7 –117.2)
110.8 (107– 114.6)
108.6 (105.3 –111.9)
0.061
127.3 (124.5 –130.1)
127 (124 – 129.9)
123.5 (120.3 – 126.6)
0.092
Overall
123.7 (120.1 –127.4)
122.3 (119.2 –125.4)
122.8 (119.0 –126.7)
0.728
100.1 (98.1 – 102.0)
95.7 (93.9 – 97.5)
95.1 (93.3 – 96.9)
19–40 years
112.7 (107.6 –118)
113.4 (109.2 –117.8)
111.4 (105.7 –117.3)
0.795
80.9 (78.5 – 83.3)
76.5 (74.4 – 78.7)
77.3 (74.8 – 79.9)
40–65 years
135.4 (130.9 –140)
130.6 (126.3 –135.1)
133.1 (128.2 –138.3)
0.452
107.6 (104.3 –110.9)
101.3 (98.2 – 104.5)
98.6 (95.7 – 101.6)
112 (104.2 –120.3)
114.3 (107.9 –121.1)
117.3 (110.1 –125)
0.351
123.3 (118.1 –128.7)
127.2 (122.2 – 132.5)
127.2 (120.8 – 133.8)
Overall
141.5 (139.9 –143.2)
139.8 (138.2 –141.5)
141.1 (139.3 –143)
0.631
138.5 (137.2 –139.8)
137.7 (136.4 – 139)
137.5 (135.9 – 139)
0.307
19–40 years
136.6 (134.1 –139.2)
134.1 (131.5 –136.7)
135.8 (133– 138.5)
0.521
120.9 (119 – 122.8)
120.7 (119.1 – 122.3)
120.6 (118.5 – 122.6)
0.826
TG (mg/dl)
65 years
,0.001 0.024 ,0.001 0.331
Non-HDL-C (mg/dl)
40–65 years
145.4 (143.3 –147.5)
144.8 (142.7 –146.9)
146.2 (143.7 –148.7)
0.686
145.9 (143.9 –147.9)
143.7 (141.6 – 145.8)
143.9 (141.5 – 146.2)
0.163
65 years
138.5 (134.4 –142.6)
136.5 (132.8 –140.2)
135.4 (131.6 –139.2)
0.265
154.1 (151.1 –157.2)
155.4 (152 – 158.8)
152.2 (148.6 – 155.7)
0.483
4.5 (4.45 –4.56)
4.23 (4.18 –4.28)
4.26 (4.19 –4.32)
,0.001
4.09 (4.05 – 4.13)
3.87 (3.84 – 3.91)
3.85 (3.82 – 3.89)
,0.001
4.33 (4.25 –4.41)
4.04 (3.97 –4.12)
4.08 (3.99 –4.17)
,0.001
3.58 (3.52 – 3.63)
3.36 (3.31 – 3.41)
3.38 (3.32 – 3.44)
,0.001 ,0.001
TC/HDL-C Overall 19–40 years 40–65 years
4.62 (4.55 –4.70)
4.35 (4.28 –4.42)
4.37 (4.28 –4.46)
,0.001
65 years
4.43 (4.28 –4.59)
4.25 (4.15 –4.35)
4.23 (4.08 –4.37)
0.047
4.26 (4.2 – 4.32)
4.01 (3.95 – 4.07)
3.96 (3.9 – 4.02)
4.63 (4.53 – 4.73)
4.51 (4.42 – 4.61)
4.45 (4.33 – 4.57)
0.017
LDL-C/HDL-C 2.79 (2.75 –2.84)
2.57 (2.53 –2.61)
2.59 (2.53 –2.64)
,0.001
2.57 (2.54 – 2.60)
2.39 (2.36 – 2.42)
2.38 (2.35 – 2.41)
,0.001
2.69 (2.62 –2.75)
2.43 (2.37 –2.5)
2.48 (2.41 –2.55)
,0.001
2.19 (2.14 – 2.23)
2.01 (1.97 – 2.05)
2.02 (1.98 – 2.07)
,0.001
40–65 years
2.85 (2.79 –2.91)
2.65 (2.59 –2.7)
2.65 (2.58 –2.73)
,0.001
2.7 (2.65 – 2.75)
2.5 (2.45 – 2.55)
2.48 (2.43 – 2.53)
,0.001
Continued
289
Overall 19–40 years
T R E N DS I N L I P I D P RO F I L E S A M O NG S O U T H KO R E A N A D U LTS
Overall
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50 40 30 Overall Men Women
20 10 0 2005
2010 2008 Prevalence of dyslipidemia
(%) 8 6 4 Overall Men Women
2 0
2005 2008 2010 Rates of lipid-lowering medication use
Fig. 1 Trends in age-adjusted prevalence of dyslipidemia and the rates of use of lipid-lowering medication in Korean adults in the 2005, 2008,and 2010 KNHANES. are presented as mean + 95% confidence intervals. The P for trend was estimated using a general linear model.
3.93 (3.78 – 4.09) 0.723 3.85 (3.65 –4.07) 3.77 (3.59 –3.94) 3.79 (3.56 –4.04) 65 years
KNHANES, Korea National Health and Nutrition Examination Survey; TC, total cholesterol; TG, triglycerides; LDL-C, low-density lipoprotein cholesterol; HDL-C, high-density lipoprotein cholesterol. Data
,0.001
0.992 3.93 (3.74 – 4.13)
,0.001
4.08 (3.95 –4.2) 4.4 (4.26 –4.54) 40–65 years
4.12 (3.98 –4.27)
3.45 (3.36 – 3.55)
3.93 (3.79 – 4.07)
3.09 (3.02 – 3.17)
,0.001
0.004
3.18 (3.1 – 3.26)
2.57 (2.5 – 2.64)
3.03 (2.99 – 3.08) 3.06 (3.01 – 3.11)
2.55 (2.49 – 2.61)
3.27 (3.21 – 3.33)
2.75 (2.69 – 2.82)
0.004
0.047
3.89 (3.78 –4.00) 3.87 (3.79 –3.96)
3.62 (3.51 –3.73)
4.10 (3.99 –4.21)
3.79 (3.64 –3.94)
Overall
19–40 years
TG/HDL-C
3.58 (3.43 –3.74)
2.76 (2.67 – 2.85) 2.84 (2.77 – 2.92) 2.98 (2.9 – 3.05) 0.007 2.56 (2.44 –2.68) 2.61 (2.52 –2.71)
2010 2008 2005
2.79 (2.66 –2.92) 65 years
2005
Women P for trend Men
(%) 60
non-HDL-C levels and TC/HDL-C, LDL-C/HDL-C and TG/HDL-C ratios and the age- and sex-adjusted mean HDL-C level increased significantly from 2005 to 2008 and to 2010. Among diabetic subjects not taking lipid-lowering medication, there were also decreasing trends in age- and sexadjusted mean non-HDL-C level and TC/HDL-C and LDL-C/HDL-C ratios, and age- and sex-adjusted mean HDL-C levels increased linearly over the study period. In the obesity group, there were linearly decreasing trends in age- and sex-adjusted geometric means of TG and TG/ HDL-C ratio and means of TC/HDL-C and LDL-C/ HDL-C ratios. Age- and sex-adjusted mean TC and HDL-C levels increased linearly within the group. Similar trends over this period occurred in obese subjects who did not use lipid-lowering medication.
Discussion Main findings of this study
From 2005 to 2008 and to 2010, there was a declining trend in the prevalence of dyslipidemia, and the rates of use of lipid-lowering medication increased linearly for Korean adults overall, for men and for women. Slightly increasing trends in the age-adjusted mean TC level were observed in both Korean men and women. However, the mean TC level has continued to be ,200 mg/dl in both sexes. The age-adjusted
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2008
2010
,0.001
P for trend
J O U RN A L O F P U B LI C H E A LT H
Table 1 Continued
290
T R E N DS I N L I P I D P RO F I L E S A M O NG S O U T H KO R E A N A D U LTS
291
Table 2 Trends in age- and sex-adjusted mean lipid profiles in subjects not taking lipid-lowering medication in the 2005, 2008 and 2010 KNHANES 2005 n
5148
2008
2010
P for trend
5983
5330
187.3 (186.1 –188.6)
188.5 (187.2 –189.8)
,0.001
45.2 (44.8 –45.5)
48.5 (48.1 –48.9)
48.7 (48.3 –49.1)
,0.001
LDL-C (mg/dl)
115.3 (114.3 –116.3)
114.5 (113.4 –115.5)
115.5 (114.3 –116.6)
0.958
TG (mg/dl)
108.9 (106.8 –111)
105.7 (103.9 –107.5)
105.3 (103.3 –107.3)
0.012
Non-HDL-C (mg/dl)
139.8 (138.5 –141.1)
TC (mg/dl)
185 (183.8 –186.2)
HDL-C (mg/dl)
139.9 (138.8 –141)
138.9 (137.7 –140)
TC/HDL-C
4.27 (4.23 –4.3)
4.03 (3.99 –4.07)
4.04 (4– 4.08)
,0.001
LDL-C/HDL-C
2.67 (2.64 –2.69)
2.47 (2.44 –2.5)
2.48 (2.45 –2.52)
,0.001
3.6 (3.54 –3.66)
3.38 (3.34 –3.43)
3.37 (3.32 –3.42)
,0.001
TG/HDL-C
0.802
HDL-C, high-density lipoprotein cholesterol. Data are presented as mean + 95% confidence intervals. The P for trend was estimated using a general linear model.
mean HDL-C level increased linearly in both Korean men and women during the same period. There were no significant changes in age-adjusted mean LDL-C level in both sexes, and the level was slightly .100 mg/dl over the 6-year study period. The age-adjusted geometric mean TG level did not change in men but was in a declining trend for women. There were significantly decreasing trends in age-adjusted mean lipid-related ratios in both men and women. In addition, similar patterns in the age- and sex-adjusted mean TC and HDL-C levels and lipid ratios were observed in Korean adults not taking lipid-lowering medication. The favorable trends were also observed in subjects with hypertension, diabetes or obesity irrespective of the lipid-lowering medication use. What is already known on this topic
Declines in TC and LDL-C levels have been recently noted in developed countries such as North America, Western countries and Australasia.20,21 In the USA between 1988 and 2010, although the age-adjusted mean TC, LDL-C, TG and non-HDL-C levels were still higher than those in South Korea, the mean TC, LDL-C and non-HDL-C levels decreased and the mean HDL-C level increased linearly. In addition, the trends among American adults not receiving lipid-lowering medication were similar to those for adults overall.22 The continuously ongoing efforts to lower cholesterol levels in the USA made these favorable trends in lipids and lipoproteins and decreased the risk of CVD. Among Korean adults, hypo-HDL-cholesterolemia and hypertriglyceridemia were previously reported as dominant subtypes of dyslipidemia and were considered to be caused by a carbohydrate-centered diet and correlated with an increased prevalence of obesity and diabetes.16,23,24
What this study adds
Compared with a previous study, notable changes in lipid profiles for Korean adults over this period were favorable trends in HDL-C level and lipid ratios and lowered TG level in women. The changes in HDL-C levels observed in this study may be more attributable to changes in lifestyle than an increasing tendency to use lipid-lowering medication given that similar trends continued in those who did not use lipidlowering medication. In addition to genetic factors, various environmental factors such as alcohol consumption, cigarette smoking, physical activity and dietary components are determinants of HDL-C level. Studies have shown that moderate alcohol consumption increases and cigarette smoking decreases HDL-C levels.25,26 Increased physical activity is known to be associated with higher HDL-C level.26 A moderate-fat diet in comparison with a low-fat diet has been shown to raise the serum HDL-C level, and a polyunsaturated fat-rich diet or a low-glycemic-index carbohydrate diet may also improve the HDL-C profile.26,27 The rate of current smoking in Korean men decreased from 51.6% in 2005 to 48.3% in 2010. The drinking rate for a month showed increasing tendency in both sexes, but high-risk alcohol drinking rate did not show linear changes in the same period. The proportions of total fat or carbohydrate intakes of total calories in Korean adults were not changed significantly within the period. The rate of physical activity with more than moderate degree showed decreasing trends in the period.28 In light of declining trends in mean lipid-related ratios, favorable lifestyle changes such as decreased current smoking rate appear to be more contributable to increasing trend in HDL-C level because undesirable lifestyle changes such as increased drinking rate or decreased physical activity can also elevate the TC, LDL-C and TG levels.
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KNHANES, Korea National Health and Nutrition Examination Survey; TC, total cholesterol; TG, triglycerides; LDL-C, low-density lipoprotein cholesterol;
292
n
TC
HDL-C
LDL-C
TG
Non-HDL-C
TC/HDL-C
LDL-C/HDL-C
TG/HDL-C
Subjects with hypertension 2005 1277
193.2 (191.1 – 195.2)
2008 1601
195 (192.6 – 197.4)
2010 1822
193.9 (191.7 – 196.1)
P for trend
0.618
43.6 (42.9 – 44.2) 119.6 (117.7 –121.5) 135.4 (131 –140) 46.7 (46 –47.4)
149.6 (147.6 –151.6)
4.61 (4.54 –4.68)
2.86 (2.81 – 2.91)
118.9 (116.7 –121.1) 129.8 (125.5 – 134.2) 148.3 (145.9 –150.6)
4.35 (4.28 –4.42)
2.66 (2.6 – 2.72)
46.5 (45.9 – 47.2) 117.5 (115.5 –119.5) 131.9 (128.3 – 135.5) 147.3 (145.2 –149.4) ,0.001
0.14
0.205
0.121
4.32 (4.26 –4.39) ,0.001
2.62 (2.57 – 2.67) ,0.001
4.3 (4.17 – 4.44) 3.98 (3.87 – 4.1) 4.04 (3.95 – 4.14) 0.002
Hypertensive subjects who did not use lipid-lowering medication 2005 1230
193.1 (191 –195.2)
43.5 (42.8 – 44.2) 119.4 (117.5 –121.4) 135.8 (131.3 – 140.4) 149.6 (147.6 –151.6)
4.62 (4.55 –4.69)
2.86 (2.81 – 2.91)
4.32 (4.18 – 4.46)
2008 1464
196.2 (193.7 – 198.8)
46.5 (45.8 – 47.3) 120.3 (118.1 –122.5)
4.39 (4.32 –4.46)
2.7 (2.64 – 2.76)
3.99 (3.88 – 4.12)
2010 1600
195.8 (193.5 – 198.1)
P for trend
0.072
46.3 (45.6 – 47) ,0.001
130 (125.6 – 134.5) 149.7 (147.3 –152.1)
119.6 (117.6 –121.7) 132.3 (128.4 – 136.3) 149.5 (147.3 –151.7) 0.859
0.218
0.964
4.39 (4.33 –4.46) ,0.001
2.69 (2.63 – 2.74) ,0.001
4.06 (3.96 – 4.18) 0.003
Subjects with diabetes 2005
416
193 (188.9 – 197.2)
4.8 (4.67 –4.93)
2.99 (2.88 – 3.09)
4.62 (4.41 – 4.84)
2008
583
191.7 (187.9 – 195.5)
43.6 (42.8 – 44.5)
117 (113.8 –120.3) 137.7 (130.9 – 145)
148.1 (144.5 –151.7)
4.54 (4.44 –4.64)
2.78 (2.69 – 2.86)
4.35 (4.17 – 4.54)
2010
528
186.8 (183.2 – 190.4)
44.5 (43.3 – 45.7) 111.1 (107.4 –114.8) 137.6 (130 –145.6)
142.3 (138.5 –146.2)
4.37 (4.23 –4.51)
2.60 (2.48 – 2.72)
P for trend
0.033
41.7 (40.7 – 42.7) 119.9 (116 – 123.7)
,0.001
0.002
143.4 (136.4 – 150.7) 151.4 (147.3 –155.5)
0.268
0.002
,0.001
,0.001
4.32 (4.11 – 4.54) 0.045
Diabetic subjects who did not use lipid-lowering medication 2005
394
193.8 (189.5 – 198.1)
41.8 (40.7 – 42.8) 120.3 (116.2 –124.4) 143.9 (136.5 – 151.8)
152 (147.7 –156.2)
4.81 (4.67 –4.94)
2.99 (2.88 – 3.1)
4.63 (4.4 – 4.86)
2008
528
192.1 (187.9 – 196.3)
43.1 (42.2 – 44)
149 (145 – 152.9)
4.59 (4.49 –4.69)
2.82 (2.74 – 2.91)
4.38 (4.19 – 4.58)
2010
428
190.1 (185.9 – 194.2)
44.6 (43.3 – 45.9) 114.6 (110.4 –118.8) 137.2 (128.3 – 146.8) 145.5 (140.9 –150)
4.45 (4.28 –4.62)
2.69 (2.55 – 2.83)
P for trend
0.236
0.001
117.9 (114.4 –121.5) 137.7 (130.5 – 145.3) 0.061
0.239
0.042
,0.001
,0.001
4.31 (4.05 – 4.57) 0.058
Subjects with obesity 2005 3539
181 (179.6 – 182.4)
46.4 (46 –46.8)
2008 4238
183 (181.7 – 184.3)
49.7 (49.3 – 50.2) 111.1 (109.9 –112.2)
112.2 (111 – 113.4)
2010 3879
183.6 (182.4 – 284.9)
P for trend
0.005
50.2 (49.7 – 50.6) 111.5 (110.3 –112.6) ,0.001
0.326
100 (97.8 –102.2)
134.6 (133.3 –135.8)
4.06 (4.02 –4.09)
2.53 (2.5 – 2.56)
3.31 (3.25 – 3.37)
96.8 (95.2 –98.5)
133.3 (132 – 134.6)
3.84 (3.8– 3.87)
2.34 (2.31 – 2.37)
3.12 (3.07 – 3.16)
95.4 (93.3 –97.6)
133.5 (132.2 –134.7)
0.004
0.184
3.81 (3.77 –3.85) ,0.001
2.33 (2.3 – 2.36) ,0.001
3.07 (3.01 – 3.13) ,0.001
Obese subjects who did not use lipid-lowering medication 2005 3509
180.8 (179.4 – 182.2)
46.1 (45.7 – 46.6) 112.1 (110.8 –113.3) 101.1 (98.8 –103.4)
134.7 (133.4 –136)
4.08 (4.04 –4.11)
2.54 (2.51 – 2.57)
3.34 (3.28 – 3.41)
2008 4142
182.9 (181.5 – 184.2)
49.4 (48.9 – 49.9) 111.1 (109.9 –112.2)
97.7 (96 –99.4)
133.5 (132.2 –134.7)
3.86 (3.82 –3.9)
2.36 (2.33 – 2.39)
3.15 (3.1 – 3.2)
96.2 (93.8 –98.5)
134.1 (132.8 –135.4)
2010 3721 P for trend
184 (182.7 – 185.3) ,0.001
49.9 (49.4 – 50.4) 111.9 (110.8 –113.1) ,0.001
0.751
0.003
0.435
3.84 (3.8– 3.89) ,0.001
2.35 (2.32 – 2.39) ,0.001
3.1 (3.03 – 3.16) ,0.001
TC, total cholesterol; TG, triglycerides; LDL-C, low-density lipoprotein cholesterol; HDL-C, high-density lipoprotein cholesterol. Data are presented as mean + 95% confidence intervals. The P for trend was estimated using a general linear model.
J O U RN A L O F P U B LI C H E A LT H
Table 3 Trends in age- and sex-adjusted mean lipid profiles according to use of lipid-lowering medication in the subgroups of hypertension, diabetes and obesity
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T R E N DS I N L I P I D P RO F I L E S A M O NG S O U T H KO R E A N A D U LTS
Limitations of this study
The present study has several limitations. Our analysis was based on data from 3 years of the KNHANES over a 6-year period. The specific types of lipid-lowering medication could not be investigated because only self-reported data for use of any lipid-lowering medication were collected. We could not consider the effect of genetic factors on lipid profiles, and we had limited data for the impact of lifestyle factors on the lipid profiles in the same survey period. Despite these limitations, as nationally representative data, the KNHANES enables us to evaluate the accurate health status of contemporary Koreans as a single ethnicity. Further data from following surveys are needed to confirm these trends, and further research is warranted to investigate simultaneously the effects of various lifestyle factors.
Conclusion Based on data from the 2005, 2008 and 2010 KNHANES, there was a decrease in the prevalence of dyslipidemia and an increase in the use of lipid-lowering medication in Korean adults. Favorable trends in HDL-C level and lipid-related ratios in both men and women and in TG level in women were observed among South Korean population, and these trends were consistent even in subjects who were not treated with lipid-lowering medication. Although favorable trends were also observed in subjects with hypertension, diabetes or obesity, not all of the lipid profiles showed a favorable tendency in these subgroups. These findings suggest that more intense strategies are needed to control dyslipidemia and prevent future cardiovascular risk.
Supplementary data Supplementary data are available at the Journal of Public Health online.
Funding None.
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Another noteworthy point from the present study was the improving trend in the TG level in female subjects over the survey years. Both overall and abdominal adiposity are strongly associated with hypertriglyceridemia,23 and the trend in the TG level correlates with the secular trend in the prevalence of obesity in Korean women, which decreased in the youngerand middle-aged subgroups but increased in the older subgroup. These trends seem to be influenced by the increased participation of Korean women in socioeconomic activity, the consequent rise in age at marriage and a lowered birth rate, and the social preference for thin women.29 Additionally, the mean TC, LDL-C, TG and non-HDL-C levels and lipid ratios in women older than 65 years of age were higher than those in men of the same age. The possible cause is thought to be caused by hormonal effects. Premenopausal women have lower lipid levels than men of the same age but lipid levels in postmenopausal women increase and become higher than those of men.24 Meanwhile, there were also favorable trends in some lipid profiles in subgroups of subjects, such as those with hypertension, diabetes and obesity. These patterns persisted among subjects who did not take lipid-lowering medication in each subgroup. All of the trends in each subgroup are consistent with the improvement in awareness and control rate of cardiovascular risk factors from 1998 to 2007 in South Korea.30 However, control remains inadequate, especially in diabetic patients, who had an LDL-C level .100 mg/dl. Hypertension, diabetes and obesity are substantial risk factors for CHD, and they enhance the morbidity and mortality of CVD with uncontrolled dyslipidemia.31,32 Therefore, serum lipid and lipoprotein levels in subjects with diabetes and hypertension should be controlled strictly to prevent macrovascular or microvascular complications.33,34
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