Efficacy and safety of curcumin in maintaining remission during disease-modifying antirheumatic drug withdrawal in rheumatoid arthritis at 52 weeks: a phase III double-blind, randomized placebo-controlled trial

Curcumin has anti-inflammatory properties but current evidence is limited to advocate its use in rheumatoid arthritis (RA). We explored whether curcumin could maintain remission in patients with RA while tapering conventional synthetic Disease-Modifying Antirheumatic Drugs (csDMARD). In this patient-and investigator-blinded trial, adults with RA in sustained remission for more than six months were randomized to oral curcumin (1 g) with piperine (5 mg) twice daily or matching placebo. Patients who had received biological DMARDs or curcumin supplements in the last 6 months were excluded. csDMARD were tapered and stopped sequentially as per a fixed protocol. The primary outcome was flare-free survival at 52 weeks. The secondary outcomes were flare rate, correlation of serum curcuminoid levels with flares and safety. 200 patients (100 per arm) entered the trial with comparable baseline characteristics. Per protocol analysis included 92 and 93 participants in the curcumin and the placebo group, respectively. Flare-free survival at week 52 was similar between both groups (60% versus 64%; p = 0.76). The median time to flare was similar [Curcumin: 219 days (IQR: 123) versus placebo: 214 days (95.8); p = 0.067]. Cox proportionate regression modelling showed that the flare-free survival was independent of serum curcuminoid levels [adjusted HR = 0.99 (95% CI: 0.97–1.0)]. The model showed that flare-free survival was not associated with age, gender, seropositivity, or csDMARD used at baseline. No serious adverse effects were noted. Curcumin did not impact the flare-free survival in patients with RA in remission during the tapering of csDMARDs despite achieving adequate serum levels. Trial registration: CTRI/2018/04/013279.