WHAT IS ALREADY KNOWN ABOUT THIS SUBJECT: * The increasing evidence of the anti-inflammatory action of statins has stimulated interest in whether these might be beneficial in disease management of rheumatoid arthritis (RA), a chronic diseases characterized by high levels of inflammation. * The TARA trial (McCarey 2004) suggested a significant reduction in disease activity outcomes in RA patients randomized to atorvastatin compared with those assigned to the placebo harm. * However, as the signal reported by the trial was small, more evidence is needed. WHAT THIS PAPER ADDS: * We investigated the possible anti-inflammatory effect of statins in a cohort of RA patients using a large health insurance claims database. * To our knowledge, this is the largest study ever conducted on the anti-inflammatory effects of statins. * Our data do not show any beneficial effect of statins in reducing disease inflammation in RA patients. AIM: To investigate the possible anti-inflammatory effect of statins in a cohort of rheumatoid arthritis (RA) patients. METHODS: We conducted a cohort study consisting of all patients with at least one claim for RA using LifeLink, a health insurance claims database. Initiation and cessation of oral steroid (OS) therapy were treated as surrogate for inflammatory flare-up and controlled inflammation, respectively. We split the RA patients into two sub-cohorts based on whether they were using OS within a specified time window of the RA index date (first recorded claim for RA in the database). Cox proportional hazard models were used to evaluate the association between time-varying exposure to any statins and (i) initiation of OS therapy in the non-users of OS at RA index date and (ii) cessation of OS therapy in the users of OS at RA index date controlling for potential confounders. RESULTS: We found 31 451 non-users of OS at RA index date and 6026 users of OS within the time window at RA index date. The results on both sub-cohorts were both consistent with no association of statin exposure with the risk of initiation/cessation of OS: the hazard ratio (HR) of initiating OS therapy was 0.96 (95% confidence interval 0.9, 1.01) in the sub-cohort of non-users and the HR of cessation of OS therapy was 0.95 (0.87, 1.05) in the sub-cohort of users of OS therapy at RA diagnosis. CONCLUSIONS: These data do not show any beneficial effect of statins in reducing disease inflammation in RA patients.