Obesity
Original Article EPIDEMIOLOGY/GENETICS
Racial Disparity in Life Expectancies and Life Years Lost Associated with Multiple Obesity-Related Chronic Conditions Su-Hsin Chang1, Yao-Chi Yu2, Nils P. Carlsson1, Xiaoyan Liu3, and Graham A. Colditz1
Objective: This study investigated racial disparity in life expectancies (LEs) and life years lost (LYL) associated with multiple obesity-related chronic conditions (OCCs). Methods: Data from the Medical Expenditure Panel Survey, 2008-2012, were used. Four OCCs were studied: diabetes, hypertension, coronary heart disease (CHD), and stroke. LE for each subpopulation was simulated by Markov modelling. LYL associated with a disease for a subpopulation was computed by taking the difference between LEs for members of that subpopulation without disease and LEs for members of that subpopulation who had that disease. Racial disparities were measured in the absolute differences in LE and LYL between black women/men and white women/men. Results: Black individuals had higher risks of developing diabetes, hypertension, and stroke. This disparity in LE between white and black participants was largest in men age 40 to 49 with at least stroke: black men lived 3.12 years shorter than white men. The disparity in LYL between white and black participants was largest in women age 70 to 79 with at least CHD: black women had 1.98 years more LYL than white women. Conclusions: Racial disparity exists in incident disease and mortality risks, LEs, and LYL associated with multiple OCCs. Efforts targeting subpopulations with large disparities are required to reduce disparities in the burden of multiple OCCs. Obesity (2017) 25, 950-957. doi:10.1002/oby.21822
Introduction Obesity and multimorbidity are prevalent in the United States. In fact, more than one in three US adults age 20 are obese (1), and more than one in four Americans have multiple concurrent chronic conditions (2). Obesity and multimorbidity are also costly. It has been estimated that 21% of US national health expenditures ($190 billion) were spent treating obesity-related illness in 2005, and US adults age 18 with two or more chronic conditions were responsible for 57% of health care expenditures in 2012 (3). Racial differences in obesity and multimorbidity are well documented. For example, 47.8% of non-Hispanic black adults age 20 had obesity compared to 32.6% of non-Hispanic white adults in 2011-2012
(1), while 22.4% of non-Hispanic black adults age 18 had at least two chronic conditions compared to 28.5% of non-Hispanic white adults in 2009 (4). Seemingly contradictory statistics such as these make clear the importance of further investigation into racial disparity at the intersection of obesity and multimorbidity. According to the 2011 US Life Tables, life expectancy (LE) at birth for the black population was 3.7 years lower than that for the white population (5), although this gap has decreased from 7.6 years in 1970 (6). Major leading causes of death contributing to this gap included heart disease, cancer, homicide, diabetes, and perinatal conditions (6), among which heart disease and diabetes are obesityrelated chronic conditions (OCCs).
1 Division of Public Health Sciences, Department of Surgery, School of Medicine, Washington University in St. Louis, St. Louis, Missouri, USA. Correspondence: Su-Hsin Chang ([email protected]) 2 Department of Electrical and Systems Engineering, School of Engineering, Washington University in St. Louis, St. Louis, Missouri 3 Division of Biostatistics, School of Medicine, Washington University in St. Louis, St. Louis, Missouri.
Funding agencies: The Foundation for Barnes-Jewish Hospital and the National Institutes of Health Grant U54 CA155496 supported this research. SHC is supported by the Agency for Healthcare Research and Quality Grant K01 HS022330. GAC is supported by the American Cancer Society Clinical Research Professorship. These sponsors had no role in the design of the study; the collection, management, analysis, and interpretation of the data; and the decision to approve publication of the finished manuscript. Disclosure: The authors declared no conflict of interest. Author contributions: SHC had full access to all of the data in the study and takes responsibility for the integrity of the data and the accuracy of the data analysis. Study concept and design: SHC. Analysis and interpretation of data: SHC, YCY, NPC, XL, GAC. Drafting of the manuscript: SHC, NPC. Critical revision of the manuscript for important intellectual content: SHC, YCY, NPC, XL, GAC. Statistical expertise: SHC, XL. Obtained funding: SHC, GAC. Administrative, technical, or material support: SHC, NPC, GAC. Study supervision: SHC, GAC. Additional Supporting Information may be found in the online version of this article. Received: 1 June 2016; Accepted: 11 February 2017; Published online 22 March 2017. doi:10.1002/oby.21822
950
Obesity | VOLUME 25 | NUMBER 5 | MAY 2017
www.obesityjournal.org
Original Article
Obesity
EPIDEMIOLOGY/GENETICS
The primary objective of this study is to investigate racial disparities in the prevalence of multiple OCCs, risks of developing multiple OCCs, and mortality, LEs, and life years lost (LYL) associated with these OCCs in the US general population age 40. We sought to study the combined disparities resulting from both biological and socioeconomic differences by race.
Methods Data We used data from the Household Component (HC) Full Year Consolidated Data of the Medical Expenditure Panel Survey (MEPS), 2008-2012, the most recent 5-year data available at the time of this study. The MEPS is a survey that provides nationally representative estimates of health care use, expenditures, sources of payment, and insurance coverage for the US civilian noninstitutionalized population (7). The HC data are based on questionnaires given to individual household members and their medical providers (7). MEPS-HC data were used to form the analytic cohort, to estimate disease risks, and to simulate LEs. To estimate mortality risk, we used data from the National Health Interview Survey (NHIS), 1988-2008, and merged the NHIS Sample Adult Files with the NHIS-Linked Mortality Public-use Files (8), which provide mortality follow-up data through December 31, 2011 (9). The NHIS is a multipurpose health survey providing information on the health of the civilian, noninstitutionalized, household population of the United States (10). The sampling frame of the MEPS-HC is drawn from the respondents to the NHIS (11).
Race We used the RACEX variable in the MEPS-HC for years 20082011, and the RACEV1X variable for year 2012 to create the race variables in our study. White/Black included people who reported themselves as white/black, with no other race reported. Other included all other respondents.
Target diseases The OCCs addressed in our study were diabetes, hypertension, coronary heart disease (CHD), and stroke. These are the most common chronic conditions for Medicare beneficiaries (12); they are also among the 20 chronic conditions defined by the US Department of Health and Human Services Interagency Workgroup on Multiple Chronic Conditions, and their data are available in the MEPS (13). In the MEPS-HC, respondents who answered “yes” to the following question were classified as having the disease: “Have you ever been told by a doctor or health professional that you have diabetes/hypertension/CHD/stroke?” Individuals who reported having a disease were then asked their age at first diagnosis.
Other variables Individuals’ age was obtained in the MEPS-HC from AGE[year]X variables, which represent the exact age, calculated from date of birth, and indicate age status as of the end of the corresponding year. Pregnancy status was obtained from PREGNTX variables, for which respondents were asked if they had been pregnant during the round; and cancer diagnosis was obtained from CANCERDX, which
www.obesityjournal.org
Figure 1 Data attrition diagram. MEPS-HC: Household Component Full Year Consolidated Data Files of the Medical Expenditure Panel Survey. n: sample size; N: estimated population size. Standard errors are in parentheses.
ascertained whether the person who answered the question had ever been diagnosed as having cancer or a malignancy of any kind. We used the BMINDX53 variable in the MEPS-HC to obtain BMI data computed from self-reported height and weight data. We then categorized into normal weight: BMI 18.5-24.9, overweight: BMI 2529.9, and obesity: BMI 30 (14).
Study population We pooled 5 years of data from the MEPS-HC, following the analytic guidelines (15). Excluding nonrespondents, we had a sample with a size of 168,214 (n 5 168,214; Figure 1). The nonresponse rate in the MEPS-HC was 59.3% for year 2008, 57.2% for year 2009, 53.5% for year 2010, 54.9% for year 2011, and 56.3% for year 2012, and it was adjusted for in the weight variables (16). We restricted our sample to adults age 40 to 84 (n 5 67,683), because these OCCs are more prevalent in the middle-aged population, and age in the MEPS was top-coded at 85 years (17). We included
Obesity | VOLUME 25 | NUMBER 5 | MAY 2017
951
Obesity
Racial Disparity and Obesity-Related Conditions Chang et al.
people who were not pregnant at the time of survey (n 5 67,515) and did not have any cancer diagnosis (n 5 59,190) (18,19). Moreover, we only kept individuals with a BMI 18.5 (n 5 56,811). We then excluded individuals who reported age of target disease diagnosis older than their age at survey or age of target disease diagnosis
Original Article EPIDEMIOLOGY/GENETICS
Racial Disparity in Life Expectancies and Life Years Lost Associated with Multiple Obesity-Related Chronic Conditions Su-Hsin Chang1, Yao-Chi Yu2, Nils P. Carlsson1, Xiaoyan Liu3, and Graham A. Colditz1
Objective: This study investigated racial disparity in life expectancies (LEs) and life years lost (LYL) associated with multiple obesity-related chronic conditions (OCCs). Methods: Data from the Medical Expenditure Panel Survey, 2008-2012, were used. Four OCCs were studied: diabetes, hypertension, coronary heart disease (CHD), and stroke. LE for each subpopulation was simulated by Markov modelling. LYL associated with a disease for a subpopulation was computed by taking the difference between LEs for members of that subpopulation without disease and LEs for members of that subpopulation who had that disease. Racial disparities were measured in the absolute differences in LE and LYL between black women/men and white women/men. Results: Black individuals had higher risks of developing diabetes, hypertension, and stroke. This disparity in LE between white and black participants was largest in men age 40 to 49 with at least stroke: black men lived 3.12 years shorter than white men. The disparity in LYL between white and black participants was largest in women age 70 to 79 with at least CHD: black women had 1.98 years more LYL than white women. Conclusions: Racial disparity exists in incident disease and mortality risks, LEs, and LYL associated with multiple OCCs. Efforts targeting subpopulations with large disparities are required to reduce disparities in the burden of multiple OCCs. Obesity (2017) 25, 950-957. doi:10.1002/oby.21822
Introduction Obesity and multimorbidity are prevalent in the United States. In fact, more than one in three US adults age 20 are obese (1), and more than one in four Americans have multiple concurrent chronic conditions (2). Obesity and multimorbidity are also costly. It has been estimated that 21% of US national health expenditures ($190 billion) were spent treating obesity-related illness in 2005, and US adults age 18 with two or more chronic conditions were responsible for 57% of health care expenditures in 2012 (3). Racial differences in obesity and multimorbidity are well documented. For example, 47.8% of non-Hispanic black adults age 20 had obesity compared to 32.6% of non-Hispanic white adults in 2011-2012
(1), while 22.4% of non-Hispanic black adults age 18 had at least two chronic conditions compared to 28.5% of non-Hispanic white adults in 2009 (4). Seemingly contradictory statistics such as these make clear the importance of further investigation into racial disparity at the intersection of obesity and multimorbidity. According to the 2011 US Life Tables, life expectancy (LE) at birth for the black population was 3.7 years lower than that for the white population (5), although this gap has decreased from 7.6 years in 1970 (6). Major leading causes of death contributing to this gap included heart disease, cancer, homicide, diabetes, and perinatal conditions (6), among which heart disease and diabetes are obesityrelated chronic conditions (OCCs).
1 Division of Public Health Sciences, Department of Surgery, School of Medicine, Washington University in St. Louis, St. Louis, Missouri, USA. Correspondence: Su-Hsin Chang ([email protected]) 2 Department of Electrical and Systems Engineering, School of Engineering, Washington University in St. Louis, St. Louis, Missouri 3 Division of Biostatistics, School of Medicine, Washington University in St. Louis, St. Louis, Missouri.
Funding agencies: The Foundation for Barnes-Jewish Hospital and the National Institutes of Health Grant U54 CA155496 supported this research. SHC is supported by the Agency for Healthcare Research and Quality Grant K01 HS022330. GAC is supported by the American Cancer Society Clinical Research Professorship. These sponsors had no role in the design of the study; the collection, management, analysis, and interpretation of the data; and the decision to approve publication of the finished manuscript. Disclosure: The authors declared no conflict of interest. Author contributions: SHC had full access to all of the data in the study and takes responsibility for the integrity of the data and the accuracy of the data analysis. Study concept and design: SHC. Analysis and interpretation of data: SHC, YCY, NPC, XL, GAC. Drafting of the manuscript: SHC, NPC. Critical revision of the manuscript for important intellectual content: SHC, YCY, NPC, XL, GAC. Statistical expertise: SHC, XL. Obtained funding: SHC, GAC. Administrative, technical, or material support: SHC, NPC, GAC. Study supervision: SHC, GAC. Additional Supporting Information may be found in the online version of this article. Received: 1 June 2016; Accepted: 11 February 2017; Published online 22 March 2017. doi:10.1002/oby.21822
950
Obesity | VOLUME 25 | NUMBER 5 | MAY 2017
www.obesityjournal.org
Original Article
Obesity
EPIDEMIOLOGY/GENETICS
The primary objective of this study is to investigate racial disparities in the prevalence of multiple OCCs, risks of developing multiple OCCs, and mortality, LEs, and life years lost (LYL) associated with these OCCs in the US general population age 40. We sought to study the combined disparities resulting from both biological and socioeconomic differences by race.
Methods Data We used data from the Household Component (HC) Full Year Consolidated Data of the Medical Expenditure Panel Survey (MEPS), 2008-2012, the most recent 5-year data available at the time of this study. The MEPS is a survey that provides nationally representative estimates of health care use, expenditures, sources of payment, and insurance coverage for the US civilian noninstitutionalized population (7). The HC data are based on questionnaires given to individual household members and their medical providers (7). MEPS-HC data were used to form the analytic cohort, to estimate disease risks, and to simulate LEs. To estimate mortality risk, we used data from the National Health Interview Survey (NHIS), 1988-2008, and merged the NHIS Sample Adult Files with the NHIS-Linked Mortality Public-use Files (8), which provide mortality follow-up data through December 31, 2011 (9). The NHIS is a multipurpose health survey providing information on the health of the civilian, noninstitutionalized, household population of the United States (10). The sampling frame of the MEPS-HC is drawn from the respondents to the NHIS (11).
Race We used the RACEX variable in the MEPS-HC for years 20082011, and the RACEV1X variable for year 2012 to create the race variables in our study. White/Black included people who reported themselves as white/black, with no other race reported. Other included all other respondents.
Target diseases The OCCs addressed in our study were diabetes, hypertension, coronary heart disease (CHD), and stroke. These are the most common chronic conditions for Medicare beneficiaries (12); they are also among the 20 chronic conditions defined by the US Department of Health and Human Services Interagency Workgroup on Multiple Chronic Conditions, and their data are available in the MEPS (13). In the MEPS-HC, respondents who answered “yes” to the following question were classified as having the disease: “Have you ever been told by a doctor or health professional that you have diabetes/hypertension/CHD/stroke?” Individuals who reported having a disease were then asked their age at first diagnosis.
Other variables Individuals’ age was obtained in the MEPS-HC from AGE[year]X variables, which represent the exact age, calculated from date of birth, and indicate age status as of the end of the corresponding year. Pregnancy status was obtained from PREGNTX variables, for which respondents were asked if they had been pregnant during the round; and cancer diagnosis was obtained from CANCERDX, which
www.obesityjournal.org
Figure 1 Data attrition diagram. MEPS-HC: Household Component Full Year Consolidated Data Files of the Medical Expenditure Panel Survey. n: sample size; N: estimated population size. Standard errors are in parentheses.
ascertained whether the person who answered the question had ever been diagnosed as having cancer or a malignancy of any kind. We used the BMINDX53 variable in the MEPS-HC to obtain BMI data computed from self-reported height and weight data. We then categorized into normal weight: BMI 18.5-24.9, overweight: BMI 2529.9, and obesity: BMI 30 (14).
Study population We pooled 5 years of data from the MEPS-HC, following the analytic guidelines (15). Excluding nonrespondents, we had a sample with a size of 168,214 (n 5 168,214; Figure 1). The nonresponse rate in the MEPS-HC was 59.3% for year 2008, 57.2% for year 2009, 53.5% for year 2010, 54.9% for year 2011, and 56.3% for year 2012, and it was adjusted for in the weight variables (16). We restricted our sample to adults age 40 to 84 (n 5 67,683), because these OCCs are more prevalent in the middle-aged population, and age in the MEPS was top-coded at 85 years (17). We included
Obesity | VOLUME 25 | NUMBER 5 | MAY 2017
951
Obesity
Racial Disparity and Obesity-Related Conditions Chang et al.
people who were not pregnant at the time of survey (n 5 67,515) and did not have any cancer diagnosis (n 5 59,190) (18,19). Moreover, we only kept individuals with a BMI 18.5 (n 5 56,811). We then excluded individuals who reported age of target disease diagnosis older than their age at survey or age of target disease diagnosis
