RA Remission Less Likely in Patients With Excess Weight

Diana Phillips

December 04, 2017

Obesity reduces the likelihood of achieving sustained remission in early rheumatoid arthritis (ERA) by nearly half, and overweight reduces it by one quarter, a new study suggests.

The findings, published online November 30 in Arthritis Care & Research, add to a growing body of literature that links obesity to poor treatment outcomes in RA. The authors suggest weight management might reduce disease activity in these patients.

To determine the effects of overweight and obesity on the likelihood of achieving sustained remission within 3 years of RA diagnosis, Susan Goodman, MD, from the Hospital for Special Surgery and Weill Cornell Medical School in New York City, and colleagues analyzed data from the Canadian Early Arthritis Cohort (CATCH), a multicenter prospective study.

A total of 982 CATCH patients met the criteria for the current analysis, including a RA diagnosis based on 1987 American College of Rheumatology or 2010 American College of Rheumatology/European League Against Rheumatism criteria, sufficient data to calculate body mass index (BMI), and disease activity score [DAS] 28 joints at baseline and two or more consecutive visits between 6 months and 3 years. Of those patients, 315 (32.1%) had a healthy BMI (18.5 - 24.9 kg/m2), 343 (34.9%) were overweight (BMI, 25 - 29.9 kg/m2), and 324 (33.0%) were obese (BMI, 30 kg/m2 or higher).

The overweight and obese patients were more likely than their healthy weight peers to be older and male. They were also more likely to have more comorbid conditions, higher C-reactive protein levels, and worse function, but their composite disease activity measures and other RA-related clinical variables were similar, the authors report. Initial treatment with disease-modifying antirheumatic drugs and subsequent biologic use were also similar across the BMI groups, they note.

Overall, 355 patients (36%) achieved sustained remission during the 3-year follow-up, of which nearly half (45%) were healthy weight, 37% were overweight, and 26% were obese. After adjusting for demographic and disease-related factors, patients who were overweight were 25% less likely to achieve sustained remission as patients who were healthy weight (HR, 0.75, 95% confidence interval [CI], 0.58 - 0.98), whereas patients who were obese were 47% less likely than their healthy weight peers (HR, 0.53; 95% CI, 0.39 - 0.71).

In a subgroup analysis, the obese group was further separated into two categories (obese I [BMI, 30 - 34.9 kg/m2] and obese II/III [BMI, 35 kg/m2 and higher]) to examine the dose-response relationship between weight and sustained remission. In the adjusted analysis, the likelihood of achieving sustained remission at 3 years compared with healthy weight patients was 43% lower in the obese I group (n = 193; HR, 0.57; 95% CI, 0.41 - 0.81) and 53% lower in the obese II/III group (n = 131; HR, 0.47; 95% CI, 0.31 - 0.71).

No significant differences were observed between BMI groups and time to initiation of biologic drug treatment in sensitivity analyses. Additional sensitivity analyses looking at the influence of BMI on the individual components of the DAS28 (tender joint count, swollen joint count, visual analogue scale score of the patient's global health, and erythrocyte sedimentation rate) over the course of 3 years linked obesity to reduced improvement across all 4 components and overweight with improvement in tender joint counts, according to the authors.

"These are the first findings to demonstrate the impact of obesity on achieving sustained remission in an ERA cohort and lends support to the growing body of evidence linking excess weight with persistent disease activity in ERA," the authors write, noting that the findings are important for clinical care.

"In the US in 2013-14, 71% of adults age 20 and older were overweight or obese, including almost 3 in 4 men. Although this is comparable to rates in our sample and with the higher prevalence of obesity among Canadian established RA patients, it is notably higher than the Canadian general population, where obesity rates are about 10 percentage points lower than in the US," the authors state. "Thus, our findings highlight a growing proportion of newly diagnosed RA patients who are overweight or obese and who may have disease that is more challenging to control."

Multiple hypotheses related to immune mechanisms and inflammatory responses have been suggested to explain the interaction between excess weight and disease activity, according to the authors. "A better understanding of mechanisms through which excess adiposity may attenuate improvement in disease activity may help to better guide treatment strategies," they write.

Although the findings point to obesity and overweight as risk factors for persistent disease activity in RA, "what is less clear is whether intensifying treatment or losing weight yields better outcomes," the authors write. They note there is contradictory evidence around the protective effect of excess weight loss in this population.

"Given the positive impact of weight reduction on quality of life, clinicians may want to discuss with patients our data showing a negative impact of adiposity on ERA outcomes. For overweight and obese individuals, it may be helpful to facilitate access to weight management programs and other community resources to help them work towards achieving a healthier weight," the authors write.

The CATCH study has been financially supported through unrestricted research grants from Amgen, Pfizer, Hoffmann-LaRoche, UCB Canada, Bristol-Myers Squibb Canada, AbbVie Corporation, Janssen Biotech, Medexus, Eli Lilly Canada, and Sanofi Canada.

Arth Care Res. Published online November 30, 2017. Abstract

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