Plasma omega-3 levels, body mass index (BMI), and smoking history are predictors of treatment response in patients with early rheumatoid arthritis (RA), according to study data published in ACR Open Rheumatology. As such, modification of these lifestyle factors may be beneficial in improving treatment response in this population.
This study enrolled patients with recent-onset RA (disease duration <12 months) who were attending the Early Arthritis Clinic at the Royal Adelaide Hospital in Australia. The researchers aimed to examine lifestyle factors as predictors for treatment response in early RA. Patients with prior exposure to disease-modifying antirheumatic drugs (DMARDs) were excluded.
Enrollees received triple therapy with conventional synthetic DMARDs sulfasalazine, hydroxychloroquine, and methotrexate. Every 3 to 6 weeks, patients returned to the study clinic for evaluation of treatment response. If disease response was subpar at any visit, therapeutic doses were adjusted. A subset of patients received fish oil supplementation in addition to study treatment. Disease activity was evaluated using the 28-joint Disease Activity Score (DAS28) with erythrocyte sedimentation rate (ESR). The primary end points were achievement of remission (DAS28 ≤2.6) or low disease activity (DAS28 ≤3.2) at 1 year.
The study cohort comprised 300 patients, of whom 211 (70.3%) were women. Mean age at RA onset was 55.5±14.9 years, and median disease duration at enrollment was 16.0 weeks. Mean baseline DAS28 score was 5.4±1.3, suggesting high disease activity. Of 300 participants, 179 (57.6%) and 136 (43.7%) achieved DAS28 low disease activity and remission at 1 year, respectively.
In the total cohort, higher mean plasma EPA level was associated with a significantly increased likelihood of achieving DAS28 low disease activity (odds ratio [OR], 1.27; 95% CI, 1.12-1.45; P <.0001) and DAS28 remission (OR, 1.21; 95% CI, 1.08-1.36; P <.001) at 1 year. Separate logistic regression models were used to examine 2-way interactions involving BMI, sex, and plasma EPA, but no significant associations were found.
An interaction between smoking status and BMI was observed for the low disease activity outcome. Specifically, increased BMI was associated with lower odds of achieving DAS28 low disease activity among participants who reported current (OR, 0.803; 95% CI, 0.670-0.962; P =.017) and prior smoking (OR, 0.913; 95% CI, 0.842-0.991; P =.029). This association was not apparent among those who had never smoked. BMI alone was also modestly associated with RA remission (OR, 0.94; 95% CI, 0.89-0.99; P =.034).
According to these results, increased omega-3 uptake and smoking cessation may benefit patients with early RA, and weight-loss treatment may also be beneficial, particularly for patients with a history of smoking. As study limitations, the investigators noted the lack of data on potential confounders, including socioeconomic status, physical activity, and medication adherence.
Brown Z, Metcalf R, Bednarz J, et al. Modifiable lifestyle factors associated with response to treatment in early rheumatoid arthritis [published online May 26, 2020]. ACR Open Rheumatol. doi:10.1002/acr2.11132