Obesity Halves Chance for RA Remission, Study Suggests

Janis C. Kelly

May 30, 2016

Rheumatoid arthritis (RA) remission rates were significantly lower among patients who were obese compared with nonobese patients, according to a systematic review and meta-analysis reported in an article published online May 9 in Arthritis Care & Research. The authors also found that disease activity scores were significantly higher and call for studies to determine whether interventions to reduce body mass index (BMI) might also improve outcomes in RA.

Coauthor Gilaad G. Kaplan, MD, MPH, told Medscape Medical News, "Obesity is a growing problem for society. Our work adds another negative stigma to the obesity epidemic...[O]bese patients who are diagnosed with [RA] are more likely to fare worse than nonobese individuals with [RA]. Because obesity is a modifiable risk factor, future studies are needed to determine whether adding weight loss to a treatment plan will improve outcomes for these patients." Dr Kaplan is associate professor, Department of Medicine and Department of Community Health Sciences, Cumming School of Medicine, University of Calgary, Alberta, Canada.

The researchers screened 3368 journal articles that reported estimates for achieving remission in obese patients with RA compared with nonobese patients, changes in disease activity measures, patient-reported outcomes during therapy, or mortality rates in relation to BMI. They identified eight studies reporting remission rates, nine reporting disease activity measures or patient-reported outcomes, and three reporting mortality by obesity status or BMI.

A meta-analysis of remission outcomes showed that the adjusted odds ratio (OR) for achieving remission among obese patients was 0.57 (95% confidence interval [CI], 0.45 - 0.72) compared with either normal weight or overweight but nonobese patients, and 0.42 (95% CI, 0.24 - 0.76) compared with patients with RA with a normal BMI. Sustained remissions were also less likely in obese patients than in nonobese patients (OR, 0.49; 95% CI, 0.32 - 0.74).

The studies of disease activity score (DAS) changes were not suitable for meta-analysis, but most "found obese patients to have worse DAS28 or DAS, tender joint counts, inflammatory markers, patient global evaluation, pain and physical function scores during follow-up, but not swollen joint counts," the authors write.

Interestingly, in patients with RA, obesity was not associated with increased mortality in this analysis. Dr Kaplan urged caution in interpreting these data: "Death is relatively low among patients with [RA]; most people live with the disease for many decades. Consequently, mortality can be difficult to study as an outcome. Our review of studies evaluating mortality showed inconsistencies between studies, which are likely explained by study design differences between studies. I would suggest that we do not have enough data, yet, to conclude whether an association between obesity and mortality truly exists or not," he said.

Dr Kaplan added, "We found that obesity influenced meaningful outcomes for patients with [RA]. However, we do not understand why obesity influenced these outcomes. With rising rates of obesity throughout the world, it is critical that clinicians explore the reasons that obesity can influence response to medical management of [RA]. We did not formally evaluate the effect of weight loss on outcomes in [RA]. However, we hope this work motivates clinicians to study the impact of weight loss for patients with [RA]."

The study was funded by the Canadian Institutes for Health Research. The authors have disclosed no relevant financial relationships.

Arthritis Care Res. Published online May 9, 2016. Abstract

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