Background General population studies have found significant relationships between obesity and depression, including identifying obesity as a risk factor for onset of depression. In SLE and RA, rates of depression are elevated, but the role of obesity as an independent risk factor for depression in these conditions has not been studied.
Objectives To examine the risk of depression onset for obese and non-obese women with SLE or RA.
Methods Analyses use data from the National Data Bank for Rheumatic Diseases, collected at 6-month intervals primarily by questionnaire. All participants have physician confirmed SLE/RA. Depression was determined through self-report. Body mass index (BMI) was calculated from self-reported height and weight; obesity was defined using validated SLE- and RA-specific BMI cut-points (SLE ≥26.8; RA ≥26.1)1,2. Cox proportional hazard models estimated the risk of becoming depressed associated with obesity at baseline. Multivariate analyses adjusted for age, race, current smoking, prednisone use, baseline disease activity (SLE: 0-100 rating of SLE activity; RA: Rheumatoid Arthritis Disease Activity Index [RADAI]), baseline functioning (SF-36 Physical Component Score), and changes in disease activity and functioning between baseline and the interview prior to depression onset (or last observation). Women who reported current or past depression at baseline were excluded from analysis.
Results For SLE, 827 women were included; for RA, 12,844 women. Mean follow-up time was 2.7 years for SLE and 3.7 years for RA. Using disease-specific obesity criteria, 52.0% of women with SLE and 44.5% of women with RA were obese at baseline. Among women with SLE, 24.3% who were obese later developed depression, compared to 18.3% of those not obese (unadjusted hazard ratio [HR]=1.43 [1.06,1.93]). Adjusting for covariates, obesity remained a significant independent risk factor for development of depression (HR =2.82 [1.40, 5.68]). Among women with RA, 20.2% of those who were obese later developed depression, compared to 16.7% of those not depressed (HR=1.28, 95% CI 1.18,1.38). Adjusting for covariates, obesity remained a significant independent risk factor for development of depression (HR=1.14 [1.03,1.27]).
Conclusions Obesity appears to be an independent risk factor for development of depression among women with SLE and RA, even after controlling for disease activity, function, changes in disease activity and function, and other relevant factors. This is a clinically important finding, as obesity is modifiable, and reducing obesity is likely to lead to additional health benefits such as reduced cardiovascular disease.
Katz et al. Arthritis Care Res 2011; 63:261.
Katz et al. Arthritis Care Res 2013;65:62.
Disclosure of Interest None declared