Original Article

POPULATION HEALTH MANAGEMENT Volume 0, Number 0, 2014 ª Mary Ann Liebert, Inc. DOI: 10.1089/pop.2014.0062

Relationship Between Depression and Physical Activity, Disability, Burden, and Health–Related Quality of Life Among Patients with Arthritis Namita Joshi, MS,1 Rahul Khanna, MBA, PhD,1 and Ruchit M. Shah, MS1

Abstract

This study purports to examine the relationship of depression with physical activity, disability, arthritisattributable burden (joint limitation, work limitation, social activity limitation, and joint pain), and health– related quality of life (HRQOL) among arthritis patients. Data from the 2011 Behavioral Risk Factor Surveillance System, a nationally representative sample of noninstitutionalized adults in the United States, was used for the purpose of this study. Multivariable logistic regression was employed to address the study objectives. The final study sample included 167,068 arthritis patients, 45,459 of whom had comorbid depression. Arthritis patients with depression had lower odds of engaging in physical activity (odds ratio [OR] = 1.070, confidence interval [CI] 1.006–1.139) and higher odds of being disabled (OR = 1.411, CI 1.306–1.524). Arthritis patients with depression also had greater odds of arthritis-attributable joint limitations (OR = 1.551, CI 1.460– 1.648), work limitations (OR = 1.506, CI 1.414–1.604), social activity limitations (OR = 1.647, CI 1.557–1.742), and pain (OR = 1.438, CI 1.364–1.517) as compared to those without depression. Arthritis patients with versus without depression had greater odds of poor general health status (OR = 1.698, CI 1.586–1.819), physical HRQOL (OR = 1.592, CI 1.486–1.704), mental HRQOL (OR = 6.225, CI 5.768–6.718), and activity limitations (OR = 2.345, CI 2.168–2.537). Study results indicate toward a negative functional impact of depression among arthritis patients. Policy makers should consider incorporating screening and management of depression into routine clinical care of arthritis patients. (Population Health Management 2014;xx:xxx–xxx)

older adults with arthritis, Dominick et al found significant impairments in all HRQOL domains.5 Similar results were reported by Furner et al, who also found lower HRQOL among adults with arthritis as compared to those without arthritis in a nationally representative.9 Studies have reported presence of comorbid conditions as a consistent predictor of poor HRQOL among adults with arthritis.5,10 Depression has been reported to be a common comorbid condition among arthritis patients.11 As compared to the general population, depression is 2 to 3 times as prevalent among arthritis patients.12 Factors including chronic pain, disability, activity limitations, lack of adequate social support, and financial constraints are associated with the occurrence of concomitant depression among arthritis patients.11,13 Psychosocial factors including depression are said to be as important as disease manifestations in explaining disability among this patient population.14 Similar to arthritis, depression in itself places a significant toll on an individual’s health and HRQOL.9,15 The effect of chronic illnesses such as arthritis on

Introduction

A

rthritis is a disorder of the musculoskeletal system characterized by inflammation in the joints and surrounding tissues. It is the leading cause of disability among adults in the United States.1 Almost 50 million individuals in the United States have arthritis, and by 2030 this number is expected to reach 67 million.2,3 The economic burden of arthritis and other rheumatic conditions was $353 billion in 2005, and is expected to increase proportionately over the years with the projected rise in prevalence of arthritis.4 Arthritis not only causes significant disability, it also affects an individual’s health-related quality of life (HRQOL).5–7 HRQOL is a subset of quality of life (QOL), and represents the physical, psychological, and social domains of health.8 Unlike QOL, which is a broader construct and includes environmental and politico-economic factors, HRQOL represents those domains of an individual’s health that may be amenable to health care interventions. In their examination of HRQOL among

1

School of Pharmacy, The University of Mississippi, University, Mississippi.

1

2

HRQOL is said to be augmented in the presence of depression.16 A few studies have reported the adverse impact of concomitant depression on physical and psychosocial functioning among arthritis patients.14,17 Among arthritis patients, depression has been reported to be inversely related to HRQOL.17–19 Depression has been shown to be the most important predictor of mental HRQOL among patients with rheumatoid arthritis, more so than radiographic damage and disease activity.19 This study builds on the previous literature concerning the impact of depression in arthritis by examining the relationship of depression with physical activity, disability, disease burden, and HRQOL among a nationally representative sample of adults with arthritis in the United States. The study examines the incremental impact of depression on physical activity, disability, arthritis-related disease burden, and HRQOL by comparing arthritis patients with and without comorbid depression. Appreciation of the unique interaction between depression and arthritis, and the influence of depression on health and well-being of arthritis patients may have a significant impact on management and outcomes associated with arthritis. Methods Study design and data

This study utilized a cross-sectional study design. The 2011 Behavioral Risk Factor Surveillance System (BRFSS) data set was analyzed for the purpose of this study. BRFSS is a federally funded, state-based surveillance system that collects data on health risk behaviors, preventive health practices, and chronic disease prevalence in a random probability-based sample of noninstitutionalized adults ( ‡ 18 years of age) in the United States every year. Conducted jointly by the Centers for Disease Control and Prevention (CDC) and respective health departments of the 50 states and territories, the BRFSS data are collected annually through a telephonic survey. Using iterative proportional fitting (raking), the BRFSS survey data are weighted to reflect a nationally representative population. Given that de-identified BRFSS data are publicly available to researchers, this study was exempt from review by the Institutional Review Board at University of Mississippi. Information pertaining to arthritis status, depression status, physical activity, disability, arthritis-attributable burden, and HRQOL from the 2011 BRFSS data set was analyzed to address the study objectives. Study variables Arthritis status. Arthritis patients were identified as those who responded ‘‘yes’’ to the question in the 2011 BRFSS questionnaire, ‘‘Have you been told by a doctor, nurse, or other health professional that you have some form of arthritis, rheumatoid arthritis, gout, lupus, or fibromyalgia?’’ Depression status. Among arthritis patients, the presence (or absence) of depression was identified based on the response (‘‘yes’’ or ‘‘no’’) to the question in the 2011 BRFSS questionnaire, ‘‘Have you been told by a doctor, nurse, or other health professional that you have a depressive disorder, including depression, major depression, dysthymia, or minor depression?’’

JOSHI, KHANNA, AND SHAH Physical activity. Engagement in physical activity was assessed using the question in the 2011 BRFSS questionnaire, ‘‘During the past month, other than your regular job, did you participate in any physical activities or exercises such as running, calisthenics, golf, gardening, or walking for exercise?’’ Physical activity was coded as ‘‘yes’’ or ‘‘no’’ based on whether or not the patients engaged in physical activity during the past month time frame. Disability. The presence or absence of disability among patients with arthritis was determined based on their response to 2 questions in the 2011 BRFSS questionnaire: ‘‘Are you limited in any way in any activities because of physical, mental, or emotional problems?’’ and ‘‘Do you now have any health problem that requires you to use special equipment, such as a cane, a wheelchair, a special bed, or a special telephone?’’ Patients who answered ‘‘yes’’ to either of the 2 questions were considered as disabled. Arthritis burden. Arthritis burden included questions related to arthritis-attributable joint limitations, work limitations, social activity limitations, and pain in the 2011 BRFSS questionnaire. Patients with joint limitations were identified based on their response (‘‘yes’’ or ‘‘no’’) to the question, ‘‘Are you now limited in any way in any of your usual activities because of arthritis or joint symptoms?’’ Work limitation was identified based on the response (‘‘yes’’ or ‘‘no’’) to the question, ‘‘Do arthritis or joint symptoms now affect whether you work, the type of work you do, or the amount of work you do?’’ Social activity limitations were assessed based on the response (‘‘a lot,’’ ‘‘a little,’’ or ‘‘not at all’’) to the question, ‘‘During the past 30 days, to what extent has your arthritis or joint symptoms interfered with your normal social activities, such as going shopping, to the movies, or to religious or social gatherings?’’ Lastly, arthritis-related pain was assessed based on the response to the question, ‘‘During the past 30 days, how bad was your joint pain on average?’’ This question was assessed using a 0 (‘‘no pain or aching’’) to 10 (‘‘pain or aching as bad it can be’’) scale. Patients’ responses were categorized as: no pain (0), mild pain (1–3), moderate pain (4–6), severe pain (7–9), and worst possible pain (10). HRQOL. Four questions in the BRFSS survey pertain to HRQOL measurement. These questions assess 4 different domains of HRQOL: general health status, physical HRQOL, mental HRQOL, and activity limitations because of poor physical or mental health. General health status was assessed using the question, ‘‘Would you say that in general your health is: excellent, very good, fair, poor?’’ Response options included, ‘‘excellent,’’ ‘‘very good,’’ ‘‘good,’’ ‘‘fair,’’ and ‘‘poor.’’ For this study, responses were collapsed into 2 categories: good health (‘‘excellent,’’ ‘‘very good,’’ and ‘‘good’’) and poor health (‘‘fair’’ and ‘‘poor’’). Physical HRQOL was assessed by the question, ‘‘Now thinking about your physical health, which includes physical illness and injury, for how many days during the past 30 days was your physical health not good?’’ Mental HRQOL was assessed through the question, ‘‘Now thinking about your mental health, which includes stress, depression, and problems with emotions, for how many days during the past 30 days was your mental health not good?’’ Activity limitations because of poor physical or mental health were assessed through the question, ‘‘During the past 30 days, for about how many days

QUALITY OF LIFE AMONG PATIENTS WITH ARTHRITIS

3

Table 1. Bivariate Analysis Comparing Arthritis Patients with Versus without Depression On Study Variables, Behavioral Risk Factor Surveillance System (BRFSS), 2011 Variable Age 18–44 45–64 65 and older Sex Female Male Race Non-Hispanic whites Non-Hispanic blacks Hispanic Multiracial Otherc Income < $10,000 $10,000–$19,999 $20,000–$34,999 $35,000–$74,999 ‡ $75,000 Geographic region Northeast Midwest South West Employment Unable to work Retired Student/homemaker Out of work Employed Health insurance status No Yes Marital status Never married Widowed Divorced Married Education status Less than high school High school graduate Attended college/technical school College graduate Weight status Underweight Normal weight Overweight Smoking status No Yes Drinking status No Yes Physical activity No Yes

Totala n (%)

Arthritis without depression n (%)

13,550 (8.2) 69,360 (41.8) 83,232 (50.1)

7975 (6.6) 44,530 (39.5) 68,175 (56.5)

5575 (12.3) 24,830 (54.6) 15,057 (33.1)

< .0001

111,707 (67.2) 54,435 (32.8)

78,193 (64.8) 42,487 (35.2)

33,514 (73.7) 11,948 (26.3)

< .0001

133,614 13,762 8678 3174 4867

(81.4) (8.4) (5.3) (1.9) (3.0)

97,818 10,398 5673 1913 3401

(82.1) (8.7) (4.8) (1.6) (2.9)

35,796 3364 3005 1261 1466

(79.7) (8.1) (6.7) (2.8) (3.3)

< .0001

11,426 28,053 35,825 40,055 25,230

(8.1) (20.0) (25.5) (28.5) (18.0)

5979 17,992 26,027 30,724 20,246

(5.9) (17.8) (25.8) (30.4) (20.1)

5447 10,061 9798 9331 4984

(13.8) (25.4) (24.7) (23.6) (12.6)

< .0001

31,110 41,870 53,878 37,241

(19.0) (25.5) (32.8) (22.7)

22,469 31,302 38,801 26,671

(18.8) (26.3) (32.5) (22.4)

8641 10,568 15,077 10,570

(19.3) (23.6) (33.6) (23.6)

< .0001

23,169 70,803 11,941 8344 51,184

(14.0) (42.8) (7.2) (5.0) (30.9)

9656 57,580 8861 4867 39,201

(8.0) (47.9) (7.4) (4.1) (32.6)

13,513 13,223 3080 3477 11,983

(29.9) (29.2) (6.8) (7.7) (26.5)

< .0001

4820 (10.6) 40,564 (89.4)

< .0001

12,682 (7.7) 153,116 (92.4)

7862 (6.5) 112,552 (93.5)

Arthritis with depressionb n (%)

P value

13,437 37,225 32,148 82,752

(8.1) (22.5) (19.4) (50.0)

8685 29,171 19,324 63,082

(7.2) (24.3) (16.1) (52.5)

4752 8084 12,824 19,670

(10.5) (17.8) (28.3) (43.4)

< .0001

19,876 55,434 45,663 44,656

(12.0) (33.5) (27.6) (27.0)

13,404 40,750 32,122 34,012

(11.1) (33.9) (26.7) (28.3)

6472 14,684 13,541 10,644

(14.3) (32.4) (29.9) (23.5)

< .0001

2556 (1.6) 43,107 (27.2) 112,838 (71.20)

1803 (1.6) 32,832 (28.5) 80,462 (69.9)

753 (1.7) 10,275 (23.7) 32,376 (74.6)

< .0001

77,521 (46.9) 87,785 (53.1)

59,615 (49.7) 60,416 (50.3)

17,906 (39.5) 27,369 (60.5)

< .0001

89,795 (57.6) 65,972 (42.4)

62,981 (55.8) 49,823 (44.2)

26,814 (62.41) 16,149 (37.6)

< .0001

54,308 (34.1) 105,188 (66.0)

36,942 (31.9) 78,714 (68.1)

17,366 (39.6) 26,474 (60.4)

< .0001 (continued)

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JOSHI, KHANNA, AND SHAH

Table 1. (Continued) Variable Disability No Yes General health status Poor health Good health Physical HRQOL < 14 unhealthy days ‡ 14 unhealthy days Mental HRQOL < 14 unhealthy days ‡ 14 unhealthy days Activity limitation < 14 unhealthy days ‡ 14 unhealthy days Time since previous health checkup Never > 1 year ago < 1 year ago Arthritis-attributable burden Joint limitation Yes No Work limitation Yes No Social activity limitation A lot A little Not at all Joint pain Worst possible Severe Moderate Mild No Number of chronic conditions Mean ( – SD)

Totala n (%)

Arthritis without depression n (%)

127,820 (80.6) 30,639 (19.3)

96,681 (84.2) 18,138 (15.8)

31,139 (71.4) 12,501 (28.7)

56,809 (34.4) 108,525 (65.6)

33,760 (28.1) 86,323 (71.9)

23,049 (50.9) 22,202 (49.1)

< .0001

118,358 (73.9) 41,908 (26.2)

92,922 (79.9) 23,412 (20.1)

25,436 (57.9) 18,496 (42.1)

< .0001

136,616 (82.2) 25,559 (15.8)

110,368 (93.4) 7819 (6.6)

26,248 (59.7) 17,740 (40.3)

< .0001

135,388 (83.2) 27,315 (16.8)

106,017 (89.5) 12,457 (10.5)

29,371 (66.4) 14,858 (33.6)

< .0001

1137 (0.7) 30,487 (18.6) 132,372 (80.7)

789 (0.7) 20,999 (17.6) 97,418 (81.7)

348 (0.8) 9488 (21.2) 34,954 (78.0)

< .0001

80,287 (51.2) 76,553 (48.8)

51,562 (45.4) 62,074 (54.6)

28,725 (66.5) 14,479 (33.5)

< .0001

51,378 (33.3) 103,004 (66.7)

30,368 (27.1) 81,526 (72.9)

21,010 (49.5) 21,478 (50.6)

< .0001

30,611 (19.5) 39,856 (25.4) 86,204 (55.0)

15,838 (14.0) 27,614 (24.3) 70,100 (61.7)

14,773 (34.3) 12,242 (28.4) 16,104 (37.4)

< .0001

5148 20,229 39,668 37,031 9442 17.8

4172 14,115 14,648 8286 1598 17.5

< .0001

9320 34,344 54,316 45,317 11,040 166,142

(6.0) (22.3) (35.2) (29.4) (7.2) (100)

(4.6) (18.1) (35.6) (33.2) (8.5) ( – 0.01)

Arthritis with depressionb n (%)

(9.7) (33.0) (34.2) (19.4) (3.7) ( – 0.02)

P value

< .0001

a

The study sample included 167,068 arthritis patients. 45,459 patients with arthritis also reported depression. c Other includes Asians, Native Hawaiians, Other Pacific Islanders, American Indians, or Alaska Natives. All n indicate unweighted estimates. HRQOL, health-related quality of life; SD, standard deviation b

did poor physical or mental health keep you from doing your usual activities, such as self-care, work, or recreation?’’ For this study, response categories for physical HRQOL, mental HRQOL, and activity limitations because of poor physical or mental health were dichotomized into fewer than 14 days and 14 days or more. A 14-day cutoff period is commonly used by clinicians and clinical researchers.6 The validity and reliability of the 4 items assessing HRQOL domains in the BRFSS survey has been established previously.20 The length of other measures of HRQOL, such as the Medical Outcomes Study Short Forms (SF-36 and SF-12), make them impractical to use in population health surveillance efforts. To address the need for a succinct measure of HRQOL for use in population health surveillance, the CDC developed the 4-item HRQOL measure utilized in the 2011 BRFSS survey.20

Other covariates. Other covariates included in the study were age, sex, race, income, geographic region, employment status, health insurance, marital status, education, weight status, smoking status, drinking status, time since previous health check-up, and an indicator of number of chronic conditions. Age was categorized as 18–44 years, 45–64 years, and 65 years and older. Race was categorized as nonHispanic whites, non-Hispanic blacks, Hispanics, multiracial, and others. Income was divided into < $10,000, $10,000–$19,999, $20,000–$34,999, $35,000–$74,999, and ‡ $75,000. Geographic regions included were Northeast, Midwest, South, and West. Employment status consisted of unable to work, retired, student/homemaker, out of work, and employed. Health insurance status was coded as ‘‘yes’’ or ‘‘no’’ based on whether patients reported any kind of

QUALITY OF LIFE AMONG PATIENTS WITH ARTHRITIS

Table 2. Multivariable Logistic Regression Analysis Examining the Relationship Between Depression, Physical Activity, and Disability Among Patients with Arthritis, Behavioral Risk Factor Surveillance System (BRFSS), 2011 Odds ratio (95% confidence interval) Variable Depression No Yes Age 18–44 45–64 65 and above Sex Female Male Race Non-Hispanic white Non-Hispanic black Hispanic Multiracial Otherc Income < $10,000 $10,000–$19,999 $20,000–$34,999 $35,000–$74,999 ‡ $75,000 Geographic region Northeast Midwest South West Employment Unable to work Retired Student/homemaker Out of work Employed Health insurance status No Yes Marital status Never married Widowed Divorced Married Education status Less than high school High school graduate Attended college/ technical school College graduate Weight status Normal weight Underweight Overweight Smoking status No Yes Drinking status No Yes

Physical activitya

Disabilityb

Referent 1.07 (1.01–1.14)

Referent 1.41 (1.31–1.52)

Referent 1.19 (1.08–1.30) 1.55 (1.39–1.73)

Referent 1.30 (1.12–1.50) 1.46 (1.24–1.72)

Referent 0.57 (0.54–0.61)

Referent 1.02 (0.94–1.10)

Referent 1.03 (0.94–1.13) 0.96 (0.84–1.09) 0.79 (0.64–0.97) 1.00 (0.82–1.21)

Referent 1.22 (1.10–1.36) 0.83 (0.70–0.98) 1.66 (1.27–2.16) 1.01 (0.80–1.28)

Referent 0.98 (0.88–1.11) 1.02 (0.90–1.15) 0.91 (0.80–1.03) 0.80 (0.69–0.92)

Referent 1.20 (1.06–1.37) 1.01 (0.88–1.15) 0.90 (0.77–1.04) 0.76 (0.63–0.91)

Referent 1.02 (0.94–1.10) 1.07 (0.99–1.15) 0.72 (0.65–0.78)

Referent 0.89 (0.80–0.99) 0.91 (0.82–1.01) 1.16 (1.04–1.30)

Referent 0.75 (0.68–0.83) 0.77 (0.68–0.88) 0.80 (0.69–0.92) 1.07 (0.97–1.18)

Referent 0.40 (0.36–0.45) 0.30 (0.26–0.36) 0.31 (0.26–0.37) 0.17 (1.15–0.19)

Referent 0.92 (0.83–1.02)

Referent 1.40 (1.21–1.62)

Referent 1.06 (0.94–1.19) 0.99 (0.88–1.10) 1.01 (0.90–1.12)

Referent 1.25 (1.08–1.44) 0.96 (0.84–1.10) 0.87 (0.76–1.00)

Referent 0.88 (0.81–0.97) 0.69 (0.63–0.76)

Referent 1.24 (1.12–1.39) 1.70 (1.52–1.91)

0.49 (0.44–0.55)

1.87 (1.65–2.13)

Referent 1.54 (1.25–1.89) 1.35 (1.27–1.44)

Referent 1.22 (0.97–1.53) 1.31 (1.21–1.42)

Referent 1.15 (1.08–1.21)

Referent 1.06 (0.99–1.13)

Referent 0.75 (0.71–0.79)

Referent 0.77 (0.71–0.83) (continued)

5 Table 2. (Continued) Odds ratio (95% confidence interval) Variable Physical activity No Yes Disability No Yes General health status Poor health Good health Time since previous health Never > 1 year ago < 1 year ago Number of chronic conditions

Physical activitya

Disabilityb

— —

Referent 0.52 (0.48–0.55)

Referent 1.93 (1.81–2.07)

— —

Referent 0.86 (0.82–0.91) checkup Referent 0.75 (0.56–1.02) 0.67 (0.50–0.90) 0.97 (0.96–0.99)

Referent 0.36 (0.33–0.39) Referent 1.08 (0.76–1.54) 1.22 (0.87–1.72) 0.89 (0.87–0.91)

a Reference category was ‘‘yes’’ for multivariable logistic regression with physical activity as dependent variable. bReference category was ‘‘no’’ for multivariable logistic regression with disability as dependent variable. c Other includes Asians, Native Hawaiians, Other Pacific Islanders, American Indians, or Alaska Natives.

health care coverage. Marital status was categorized as never married, widowed, divorced, and married. Education status included less than high school, high school graduate, attended college/technical school, and college graduate. Based on patients’ body mass index, weight status was categorized as underweight (12–18 kg/m2), normal weight (18–24.9 kg/m2), and overweight/obese (25 kg/m2 and above). Smoking status was coded as ‘‘yes’’ if patients were ‘‘former smoker, current smoker, smokes sometimes and current smoker, smokes every day,’’ and ‘‘no’’ if the patients indicated they had ‘‘never smoked.’’ Drinking status was coded as ‘‘yes’’ or ‘‘no’’ depending on whether or not patients reported drinking over the past 30 days at the time of the survey. Time since previous health checkup was categorized as never had routine checkup, routine checkup within the past year, and routine checkup more than 1 year ago. Number of chronic conditions was computed by adding the chronic conditions reported as being present by patients (excluding arthritis and depression). Statistical analyses

Study analyses were conducted using SAS version 9.3 (SAS Institute Inc., Cary, NC). PROC SURVEY procedures in SAS were utilized to account for the complex sampling design of BRFSS data. PROC SURVEY FREQ and PROC SURVEY MEANS were used to compare frequencies and percentages of categorical variables and continuous variables, respectively. PROC SURVEY LOGISTIC was used to conduct multivariable logistic regression to examine the relationship between depression and physical activity, disability, arthritis-attributable burden (joint limitations, work limitations, social activity limitations, and pain), and HRQOL (general health status, physical HRQOL, mental HRQOL, and activity limitations because of poor physical or mental health) among arthritis patients. Odds ratios (ORs) and corresponding confidence intervals (CIs) have been

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JOSHI, KHANNA, AND SHAH

Table 3. Multivariable Logistic Regression Analysis Determining the Relationship Between Depression And Arthritis-Attributable Burden Among Adults with Arthritis, Behavioral Risk Factor Surveillance System (BRFSS), 2011 Variable

Joint limitationsa

Work limitationsa

Social activity limitationsb

Joint painc

Odds ratio (95% confidence interval) Depression No Yes Age 18–44 45–64 65 and above Sex Female Male Race Non–Hispanic white Non–Hispanic black Hispanic Multiracial Otherd Income < $10,000 $10,000–$19,999 $20,000–$34,999 $35,000–$74,999 ‡ $75,000 Geographic region Northeast Midwest South West Employment Unable to work Retired Student/homemaker Out of work Employed Health insurance status No Yes Marital status Never married Widowed Divorced Married Education status Less than high school High school graduate Attended college/ technical school College graduate Weight status Normal weight Underweight Overweight Smoking status No Yes

Referent 1.55 (1.46–1.65)

Referent 1.51 (1.41–1.60)

Referent 1.65 (1.56–1.74)

Referent 1.44 (1.36–1.52)

Referent 1.00 (0.92–1.09) 0.81 (0.74–0.90)

Referent 0.89 (0.81–0.98) 0.51 (0.46–0.57)

Referent 0.81 (0.74–0.88) 0.54 (0.49–0.60)

Referent 0.98 (0.91–1.06) 0.78 (0.71–0.85)

Referent 0.81 (0.77–0.86)

Referent 0.96 (0.90–1.02)

Referent 0.76 (0.72–0.80)

Referent 0.68 (0.65–0.72)

Referent 0.91 (0.83–1.00) 0.80 (0.70–0.91) 1.30 (1.06–1.58) 0.78 (0.66–0.93)

1.24 1.06 1.27 1.20

Referent (1.12–1.36) (0.92–1.21) (1.03–1.56) (1.00–1.44)

1.19 0.93 1.28 1.14

Referent (1.09–1.30) (0.83–1.05) (1.05–1.56) (0.96–1.37)

1.66 1.22 1.16 0.83

Referent (1.52–1.80) (1.09–1.36) (0.97–1.38) (0.71–0.98)

Referent 0.81 (0.70–0.92) 0.74 (0.65–0.85) 0.69 (0.60–0.80) 0.73 (0.63–0.85)

0.87 0.76 0.65 0.46

Referent (0.77–0.99) (0.69–0.89) (0.57–0.75) (0.40–0.54)

0.77 0.70 0.61 0.51

Referent (0.70–0.86) (0.63–0.78) (0.54–0.69) (0.45–0.58)

0.76 0.66 0.53 0.45

Referent (0.68–0.84) (0.60–0.73) (0.47–0.59) (0.40–0.51)

Referent 0.87 (0.80–0.93) 0.93 (0.86–1.00) 0.99 (0.91–1.07)

Referent 0.98 (0.90–1.07) 1.01 (0.93–1.10) 1.03 (0.94–1.13)

Referent 0.47 (0.43–0.53) 0.45 (0.39–0.52) 0.52 (0.45–0.60) 0.36 (0.32–0.40)

0.49 0.55 0.67 0.45

Referent 0.88 (0.79–0.98)

Referent 0.75 (0.67–0.83)

Referent 0.91 (0.83–1.00)

Referent 0.83 (0.76–0.91)

Referent 1.04 (0.93–1.17) 1.12 (1.00–1.25) 1.10 (0.99–1.22)

Referent 0.97 (0.86–1.10) 1.16 (1.03–1.30) 1.14 (1.02–1.27)

Referent 1.01 (0.90–1.12) 1.07 (0.96–1.18) 1.08 (0.98–1.20)

Referent 1.12 (1.01–1.24) 1.14 (1.04–1.26) 1.20 (1.09–1.31)

Referent 1.07 (0.97–1.17) 1.19 (1.08–1.31)

Referent 0.93 (0.84–1.02) 0.91 (0.82–1.00)

Referent 0.90 (0.82–0.98) 0.88 (0.81–0.96)

Referent 0.77 (0.71–0.83) 0.67 (0.61–0.73)

1.27 (1.14–1.40)

0.66 (0.60–0.74)

0.78 (0.71–0.86)

0.525 (0.478–0.576)

Referent 0.90 (0.72–1.11) 1.21 (1.14–1.28)

Referent 1.00 (0.81–1.25) 1.07 (1.01–1.14)

Referent 1.08 (0.90–1.30) 1.22 (1.16–1.30)

Referent 1.07 (0.91–1.27) 1.13 (1.08–1.19)

Referent 1.06 (1.01–1.12)

Referent 1.09 (1.03–1.15)

Referent 1.110 (1.057–1.167)

Referent 1.156 (1.106–1.207)

Referent (0.44–0.54) (0.48–0.62) (0.58–0.77) (0.410–0.50)

Referent 0.97 (0.90–1.05) 1.07 (1.00–1.15) 0.94 (0.87–1.02) 0.42 0.40 0.50 0.31

Referent (0.39–0.47) (0.35–0.45) (0.44–0.56) (0.28–0.33)

Referent 0.92 (0.86–0.99) 0.99 (0.93–1.05) 0.89 (0.82–0.95) 0.52 0.49 0.60 0.50

Referent (0.48–0.56) (0.44–0.55) (0.53–0.68) (0.46–0.55)

(continued)

QUALITY OF LIFE AMONG PATIENTS WITH ARTHRITIS

7

Table 3. (Continued) Variable

Joint limitationsa

Work limitationsa

Social activity limitationsb

Joint painc

Odds ratio (95% confidence interval) Drinking status No Referent Yes 0.99 (0.94–1.05) Physical activity No Referent Yes 0.88 (0.83–0.93) Disability No Referent Yes 3.92 (3.61–4.26) General health status Poor health Referent Good health 0.51 (0.48–0.54) Time since previous health checkup Never Referent > 1 year ago 1.08 (0.80–1.47) < 1 year ago 0.99 (0.73–1.35) Number of chronic conditions 0.98 (0.96–0.99)

Referent 0.94 (0.88–1.00)

Referent 0.89 (0.85–0.94)

Referent 0.93 (0.88–0.97)

Referent 0.88 (0.83–0.93)

Referent 0.74 (0.70–0.78)

Referent 0.79 (0.75–0.83)

Referent 2.09 (1.94–2.25)

Referent 3.61 (3.38–3.86)

Referent 2.37 (2.23–2.51)

Referent 0.56 (0.52–0.60)

Referent 0.43 (0.41–0.46)

Referent 0.50 (0.48–0.53)

Referent 0.94 (0.69–1.26) 0.88 (0.66–1.18) 1.01 (0.99–1.03)

Referent 0.85 (0.62–1.17) 0.87 (0.63–1.20) 0.98 (0.96–0.99)

Referent 0.95 (0.71–1.27) 0.96 (0.72–1.28) 0.97 (0.96–0.99)

a Reference category was ‘‘no’’ for multivariable logistic regression with arthritis-attributable joint limitations and work limitations as dependent variable. bReference category was ‘‘not at all’’ for multivariable logistic regression with arthritis-attributable social activity limitations as dependent variable. The category ‘‘a lot’’ was modeled for multivariable logistic regression with arthritis-attributable social activity limitations as dependent variable. c Reference category was ‘‘no pain’’ for multivariable logistic regression with arthritis-attributable joint pain as dependent variable. The category ‘‘worst possible pain’’ was modeled for multivariable logistic regression with arthritis-attributable joint pain as dependent variable. d Other includes Asians, Native Hawaiians, Other Pacific Islanders, American Indians, or Alaska Natives.

reported. All results were considered significant at 0.05 level of statistical significance. Results

Of the 506,467 adults who participated in the 2011 BRFSS survey, 167,068 (32.98%) were diagnosed with arthritis, and were considered to be the final sample of interest. Table 1 presents the results of bivariate analyses comparing arthritis patients with versus without depression on study variables. Roughly 27.21% arthritis patients also reported being diagnosed with depression. Bivariate comparisons revealed significant (P < 0.001) differences among arthritis patients with versus without depression across all study variables. Arthritis patients with depression were generally younger, mostly female, and of lower income as compared to arthritis patients without depression. A lower proportion of arthritis patients with versus without depression reported engaging in physical activity. A greater proportion of arthritis patients with versus without depression reported being disabled. More arthritis patients with depression reported arthritis-attributable joint limitation, work limitation, social activity, and pain, as compared to arthritis patients without depression. A greater proportion of arthritis patients with versus without depression reported having poor general health status, poor physical HRQOL, poor mental HRQOL, and activity limitations. Table 2 presents the results of multivariable logistic regression to determine the influence of depression on physical activity and disability among arthritis patients.

Arthritis patients with depression had lower odds (OR = 1.070, CI 1.006–1.139) of engaging in physical activity in the past month as compared to arthritis patients without depression. The odds of being disabled were 1.4 times greater among arthritis patients with depression in comparison to arthritis patients without depression (OR = 1.411, CI 1.306–1.524). Table 3 describes the results of multivariable logistic regression analyses examining the influence of depression on arthritis-attributable burden. Arthritis patients with depression had higher odds of arthritis-attributable joint limitations (OR = 1.551, CI 1.460–1.648), work limitations (OR = 1.506, CI 1.414–1.604), social activity limitations (OR = 1.647, CI 1.557–1.742), and pain (OR = 1.438, CI 1.364–1.517) as compared to arthritis patients without depression. The influence of depression on the HRQOL of arthritis patients has been described in Table 4. Arthritis patients with depression had a higher likelihood of having poor general health status (OR = 1.698, CI 1.586–1.819) as compared to arthritis patients without depression. The odds of having poor ( ‡ 14 unhealthy days) physical HRQOL (OR = 1.592, CI 1.486–1.704), mental HRQOL (OR = 6.225, CI 5.768–6.718), and activity limitations (OR = 2.345, CI 2.168–2.537) were higher for arthritis patients with versus without depression. Discussion

Though prior research has documented the incremental health care burden of depression among arthritis patients,

8

JOSHI, KHANNA, AND SHAH

Table 4. Multivariable Logistic Regression Determining Relationship Between Depression and HRQOL Among Patients with Arthritis, Behavioral Risk Factor Surveillance System (BRFSS), 2011 Variable

General health statusa Physical HRQOLb Mental HRQOLb Activity limitationb Odds ratio (95% confidence interval)

Depression No Yes Age 18–44 45–64 65 and above Sex Female Male Race Non-Hispanic white Non-Hispanic black Hispanic Multiracial Otherc Income < $10,000 $10,000–$19,999 $20,000–$34,999 $35,000–$74,999 ‡ $75,000 Geographic region Northeast Midwest South West Employment Unable to work Retired Student/homemaker Out of work Employed Health insurance status No Yes Marital status Never married Widowed Divorced Married Education status Less than high school High school graduate Attended college/technical school College graduate Weight status Normal weight Underweight Overweight Smoking status No Yes Drinking status No Yes

Referent 1.70 (1.59–1.82)

Referent 1.59 (1.49–1.70)

Referent 6.23 (5.77–6.72)

Referent 2.345 (2.17–2.54)

Referent 0.97 (0.87–1.08) 0.77 (0.68–0.87)

Referent 0.88 (0.79–0.97) 0.64 (0.57–0.73)

Referent 0.73 (0.65–0.81) 0.43 (0.37–0.49)

Referent 0.74 (0.65–0.83) 0.45 (0.38–0.52)

Referent 1.05 (0.98–1.12)

Referent 0.93 (0.87–1.00)

Referent 0.82 (0.76–0.89)

Referent 1.08 (0.99–1.17)

1.28 1.76 1.16 1.50

Referent (1.15–1.42) (1.52–2.05) (0.90–1.49) (1.21–1.85)

Referent 0.77 (0.68–0.87) 1.08 (0.93–1.25) 1.11 (0.87–1.41) 0.99 (0.79–1.23)

Referent 1.15 (1.01–1.30) 0.91 (0.77–1.09) 1.53 (1.19–1.99) 1.31 (1.02–1.68)

Referent 0.82 (0.71–0.95) 0.96 (0.80–1.14) 1.07 (0.84–1.38) 1.08 (0.85–1.36)

0.85 0.69 0.50 0.36

Referent (0.74–0.97) (0.61–0.79) (0.44–0.58) (0.31–0.41)

Referent 0.77 (0.68–0.88) 0.73 (0.64–0.83) 0.61 (0.53–0.71) 0.56 (0.47–0.66)

Referent 0.76 (0.66–0.87) 0.65 (0.56–0.75) 0.62 (0.52–0.73) 0.54 (0.44–0.65)

Referent 0.71 (0.62–0.81) 0.68 (0.59–0.79) 0.60 (0.51–0.71) 0.52 (0.43–0.64)

Referent 1.05 (0.95–1.15) 1.12 (1.02–1.22) 1.07 (0.97–1.19)

Referent 0.94 (0.85–1.03) 0.95 (0.87–1.04) 1.02 (0.92–1.13)

Referent 0.89 (0.79–1.00) 0.97 (0.88–1.08) 1.09 (0.96–1.22)

Referent 0.92 (0.82–1.03) 0.96 (0.86–1.07) 1.06 (0.93–1.19)

Referent (0.32–0.40) (0.35–0.46) (0.39–0.52) (0.27–0.33)

Referent 0.34 (0.31–0.38) 0.32 (0.28–0.37) 0.42 (0.36–0.49) 0.23 (0.20–0.25)

Referent 0.52 (0.46–0.59) 0.55 (0.47–0.64) 0.84 (0.72–0.98) 0.50 (0.45–0.57)

Referent 0.32 (0.29–0.36) 0.31 (0.27–0.37) 0.44 (0.38–0.52) 0.14 (0.13–0.16)

Referent 0.79 (0.70–0.88)

Referent 0.85 (0.75–0.96)

Referent 0.77 (0.67–0.87)

Referent 0.84 (0.73–0.96)

Referent 1.00 (0.88–1.15) 1.09 (0.95–1.24) 1.12 (0.99–1.27)

Referent 0.96 (0.83–1.10) 1.09 (0.95–1.25) 1.22 (1.07–1.39)

Referent 0.80 (0.68–0.94) 0.97 (0.84–1.12) 0.90 (0.78–1.04)

Referent 0.97 (0.82–1.13) 1.13 (0.98–1.30) 1.17 (1.02–1.36)

Referent 0.67 (0.60–0.73) 0.58 (0.52–0.64) 0.47 (0.41–0.52)

Referent 0.86 (0.78–0.96) 0.86 (0.77–0.96) 0.70 (0.62–0.79)

Referent 0.85 (0.75–0.96) 0.80 (0.71–0.91) 0.64 (0.56–0.74)

Referent 0.94 (0.84–1.06) 0.95 (0.84–1.08) 0.82 (0.71–0.94)

Referent 1.60 (1.25–2.06) 1.09 (1.02–1.17)

Referent 1.30 (1.05–1.61) 0.97 (0.90–1.04)

Referent 1.53 (1.10–2.14) 0.98 (0.90–1.07)

Referent 1.31 (1.00–1.71) 0.93 (0.85–1.02)

Referent 1.17 (1.10–1.24)

Referent 1.18 (1.11–1.26)

Referent 1.19 (1.10–1.28)

Referent 1.12 (1.04–1.21)

Referent 0.74 (0.705–0.79)

Referent 0.78 (0.73–0.84)

Referent 1.03 (0.95–1.12)

Referent 0.80 (0.74–0.87)

0.36 0.40 0.45 0.30

(continued)

QUALITY OF LIFE AMONG PATIENTS WITH ARTHRITIS

9

Table 4. (Continued) Variable

General health statusa Physical HRQOLb Mental HRQOLb Activity limitationb Odds ratio (95% confidence interval)

Physical activity No Yes Disability No Yes Time since previous health checkup Never > 1 year ago < 1 year ago Number of chronic conditions

Referent 0.57 (0.54–0.61)

Referent 0.55 (0.51–0.59)

Referent 0.70 (0.65–0.76)

Referent 0.49 (0.45–0.53)

Referent 2.72 (2.52–2.93)

Referent 3.19 (2.96–3.44)

Referent 1.43 (1.30–1.56)

Referent 3.04 (2.79–3.31)

Referent 0.84 (0.60–1.17) 0.83 (0.60–1.16) 0.72 (0.71–0.73)

Referent 0.87 (0.63–1.26) 0.86 (0.61–1.22) 0.85 (0.83–0.87)

Referent 0.83 (0.53–1.30) 0.68 (0.44–1.06) 0.92 (0.90–0.95)

Referent 1.04 (0.72–1.48) 0.99 (0.69–1.41) 0.88 (0.86–0.90)

a

Reference category was ‘‘good health’’ for multivariable logistic regression with general health status as dependent variable. Reference category was ‘‘ < 14 unhealthy days’’ for multivariable logistic regression with physical health-related quality of life (HRQOL), mental HRQOL, and activity limitations as dependent variables. c Other includes Asians, Native Hawaiians, Other Pacific Islanders, American Indians, or Alaska Natives. b

the true extent of the problem in a representative US sample has been lacking. Using a nationally representative database, this study assesses the incremental impact of depression on the health and well-being of arthritis patients. Specifically, this study examined the variation in physical activity, disability, arthritis-attributable burden, and HRQOL between arthritis patients with versus without depression. To the best of the research team’s knowledge, this is the first populationbased study to examine the additional burden imposed by depression in arthritis patients. When examining the relationship between the presence of depression and engagement in physical activity, significant results emerged in both bivariate and multivariable analyses. Bivariate analyses revealed that a lower proportion of arthritis patients with depression engage in physical activity as compared to arthritis patients without depression. This result persisted in multivariable analysis, when controlling for other covariates. Similar results were reported by Shih et al, who found the symptoms of frequent depression/anxiety to be associated with physical inactivity among women with arthritis.21 Physical activity plays an instrumental role in arthritis management.22,23 Studies have indicated that physical activity not only improves functional status among arthritis patients, but also prevents functional decline.24 Lack of physical activity may predispose arthritis patients to other chronic diseases.25 It has been suggested that even a low-to-moderate level of physical activity may be protective against depression,26 and may help alleviate depressive symptoms.27 The low levels of physical activity observed among arthritis patients with depression in the present study highlight the critical need for health care professionals to address this issue, particularly in this vulnerable population. Policy makers should consider developing physical activity interventions targeted toward arthritis patients with depression. The prevalence of disability was almost twice as high among arthritis patients with depression as compared with those without depression. In multivariable analysis, arthritis patients with depression were found to have *40% higher odds of being disabled as compared to those without de-

pression. Prior research has indicated a positive relationship between depression and disability in arthritis.28–30 For example, Fifield et al found that patients with rheumatoid arthritis with a lifetime diagnosis of depression had higher functional disability as compared to those without lifetime depression.30 Among patients with rheumatoid arthritis, depressive symptoms have been found to be a better predictor of functional disability than radiographic damage.19 Besides disability, the research team also found arthritisattributable joint limitations, work limitations, social activity limitations, and pain to be higher (*44%–65%) among arthritis patients with depression than those without depression. These results indicate that depression is associated with poor symptoms among arthritis patients. However, when reviewing the literature on the relationship between depression and arthritis-attributable burden, few studies emerged. In one such study, Rosemann et al found concomitant depression to be associated with an increased burden of osteoarthritis.31 In a systematic review, Katon et al found the presence of comorbid depression among individuals with chronic diseases to be associated with a higher number of medical symptoms as compared to individuals with chronic diseases without depression.32 Results from the present study together with prior research necessitate a careful assessment and management of depressive symptoms among arthritis patients. Disease management among these patients should incorporate a multifocal approach that aims to address the core symptoms of arthritis and depression. Until the relationship between depression and disease symptomology (including in arthritis) is fully understood, a focus on management of depressive symptoms could help alleviate the chronic disease burden associated with depression. Study results highlighted the incremental impact of depression on HRQOL among arthritis patients. As compared to arthritis patients without depression, those with depression had poorer HRQOL across all domains including general health status, physical HRQOL, mental HRQOL, and activity limitations. As mentioned earlier, prior studies have demonstrated similar results, wherein depression has

10

been found to negatively impact HRQOL among arthritis patients.14,17–19 In their study of psychological status and its impact on HRQOL among rheumatoid arthritis patients, Nas et al found depression to cause poor HRQOL in their study sample.33 Rosemann et al observed similar results among patients with osteoarthritis, wherein depression was found to adversely impact HRQOL and increase health care utilization among such patients.31 It is not clear how depression affects HRQOL among arthritis patients. Some suggest that illness perception and coping strategies serve as mediators in the relationship between disease and subjective wellbeing.34 Though depression influenced all domains of HRQOL in the present study, the impact of mental HRQOL was the most pronounced. Arthritis patients with depression had more than 6 times higher odds of poor mental HRQOL as compared to those without depression. Among patients already suffering from physical disability related to arthritis, the presence of depression is not only likely to worsen their physical health profile but also to cause psychological disability. For arthritis patients with depression, clinicians should consider evaluating both their physical and psychological health profile during routine office visits. This study has a few limitations. The most important limitation of this study was the cross-sectional design used for study analyses. Because of the cross-sectional nature of study data, it is not possible to infer causal relationships among study variables. Whether depression incrementally causes arthritis-attributable burden and poor HRQOL may not be clear from this study. However, the results do signify that depression is associated with poor functional status and poor health among arthritis patients, and thus depression management should be included in any arthritis management strategy among patients with both diseases. Information in the BRFSS survey is based on self-report. The arthritis and depression status of the sample was not validated by clinical assessment. Further, patients may have overreported or underreported their physical activity and health status. This study also suffers from other limitations of self-reported data including vulnerability to recall bias. Despite these limitations, the research team believes that the use of a nationally representative data set allowed for this study to make a valuable contribution to the existing literature on the relationship between depression and arthritis. This is the first study to examine the relationship between depression and physical activity, disability, arthritis-attributable burden, and HRQOL among a nationally representative sample of arthritis patients. Study results demonstrate the variation in physical activity levels among arthritis patients with versus without depression. Arthritis patients with depression were more likely to be disabled and report higher arthritisattributable burden as compared to those without depression. Further, arthritis patients with depression had poorer HRQOL across all domains as compared to arthritis patients without depression. Depression is likely to worsen the disease profile among arthritis patients, and thus should be adequately managed and treated. Author Disclosure Statement

Ms. Joshi, Dr. Khanna, and Mr. Shah declared no conflicts of interest with respect to the research, authorship, and/ or publication of this article. The authors received no fi-

JOSHI, KHANNA, AND SHAH

nancial support for the research, authorship, and/or publication of this article. References

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Address correspondence to: Dr. Rahul Khanna Faser Hall Room 236 Department of Pharmacy Administration, School of Pharmacy P.O. Box 1848, University, MS 38677 E-mail: [email protected]