Impact of weight loss on rheumatoid arthritis activity, biomarkers

Weight loss has been associated with improved rheumatoid arthritis (RA) outcomes in obese patients, according to results of a study published in Rheumatology.

Researchers conducted a 12-week randomized controlled trial in patients with a clinical diagnosis of rheumatoid arthritis, a body mass index (BMI) of at least 30 kg/m2and demonstration of power Doppler synovitis.

A total of 40 patients were randomly assigned to either a diet condition (n=20) or the control condition (n=20). Diet patients received a low calorie diet of 1000 to 1500 kcal/d with high protein meal replacements. Patients in the control condition received basic diet suggestions, but no calorie goals. The primary outcomes were improvements from baseline to week 12 in disease activity score-28 joint count (DAS-28) and power Doppler ultrasound score 34 joints (PDUS). The Health Assessment Questionnaire-Disability Index (HAQ-DI) was used to assess the impact of dietary intervention on disease activity and patient functioning. Serum levels of several biomarkers were measured at baseline and at follow-up.


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Baseline demographic and clinical characteristics were comparable between the study groups. In the total cohort, the mean age was 55.0 ± 13.2 years; 90.0% were women; 75.0% were white; and 80.0% had seropositive RA. At baseline, the mean BMI was 34.8 ± 5.7. At 12 weeks, patients in the dietary intervention had lost an average of 9.5 kg each, compared to only 0.5 kg in the control condition (P <.001). The mean DAS28 score in the diet group decreased significantly from 5.2 ± 1.2 at baseline to 4.2 ± 1.2 at 12 weeks (P <.001). While a slight reduction was observed in the control group, the difference was not significant (4.7 ± 1.0 to 4.4 ± 1.2; P =.16). The PDUS score had a numerically greater reduction in the diet group (20.8 ± 10.8 to 13.1 ± 9.1; P < 0.001) compared to the control group (16 ± 11.8 to 12.3 ± 12.1; P =.01), although the difference between the groups was not significant.

Patient-reported pain and functioning improved over time in the diet group. Additionally, HAQ-DI scores decreased significantly during the 12-week dietary intervention (0.8 to 0.6; P =.04). No proportional decreases in pain, function, and HAQ-DI scores were observed in the control condition. Serum leptin levels decreased over 12 weeks in the intervention group (P =.009), but not in the control group. Although adiponectin levels did not change significantly over time in either group, they were higher at 12 weeks in the intervention group compared to the control group (P =.037).

Study limitations included the small cohort size and short follow-up period. Further research is needed to elucidate the effects of long-term weight loss on RA activity.

The study authors concluded, “Further study is needed to validate these findings, but the results are encouraging and indicate that dietary intervention may serve as a useful adjunctive treatment for rheumatoid arthritis.”

Reference

Ranganath VK, La Cava A, Vangala S, et al. Improved outcome in rheumatoid arthritis with obesity after weight loss intervention: randomized trial. Rheumatology (Oxford). Published online May 28, 2022. doi:10.1093/rheumatology/keac307

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