Objective: We aimed to evaluate the associations between response to algorithm-directed treat-to-target conventional synthetic disease-modifying antirheumatic drug therapy and potentially modifiable lifestyle factors, including dietary fish oil supplementation, body mass index (BMI), and smoking history in a rheumatoid arthritis (RA) inception cohort. Methods: Patients with RA with a duration of less than 12 months were reviewed every 3 to 6 weeks to adjust therapy according to disease response. All patients received advice to take fish oil supplements, and omega-3 status was measured as plasma levels of eicosapentaenoic acid (EPA). Lifestyle factors and other variables potentially prognostic for 28-joint Disease Activity Score (DAS28) remission and DAS28 low disease activity (LDA) at the 12-month visit were included in multivariable logistic regression models. Results: Of 300 participants, 57.7% reached DAS28 LDA, and 43.7% were in DAS28 remission at 1 year. Increase in plasma EPA was associated with an increase in the odds of being in LDA (adjusted odds ratio [OR] = 1.27; P < 0.0001) and remission (adjusted OR = 1.21; P < 0.001). There was some evidence that the effect of BMI on LDA might be modified by smoking history. An increase in BMI was associated with a decrease in the odds of being in LDA in current and former smokers but had no impact on LDA in patients who had never smoked. There were no meaningful associations between BMI or smoking history and remission. Conclusion: Omega-3 status, BMI, and smoking history are potential predictors of outcome in early RA. The possibility of an effect modification by smoking on the predictive value of BMI merits further investigation.
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