Although randomized controlled trials (RCTs) are the gold standard for the assessment of clinical outcomes, long-term extension trials (LTEs) and observational cohorts may help generate evidence. Our goal was to compare the discontinuation rates of abatacept, rituximab, and tocilizumab in rheumatoid arthritis (RA) reported in different study designs.
A systematic review was conducted with searches in PubMed, Scopus, and the Cochrane Library, plus a manual search, for RCTs, LTEs, and observational cohorts reporting discontinuation rates by any of three causes (all-cause, inefficacy, adverse events). Meta-analyses with sensitivity analyses and meta-regressions were conducted.
Of the 111 studies included, 74 were RCTs (n = 55) or LTEs (n = 17) reporting data on abatacept (n = 33), rituximab (n = 10), and tocilizumab (n = 31) and 37 were observational cohort studies (abatacept = 11, rituximab = 8, tocilizumab = 18). The follow-up duration did not differ among the study designs. Discontinuation rates were similar among the drugs but varied among the study designs. Discontinuation rates were significantly higher in cohort studies than those in interventional studies for the three drugs. Sensitivity analyses could not identify patient characteristics associated with these differences. Meta-regression analyses demonstrated no correlation between study follow-up duration and discontinuation rates.
The discontinuation rates reported for non-anti-TNF drugs varied relative to the study design in which they were investigated. Regulatory agencies, price-setting entities, and evidence-gathering researchers should consider the effect of the real-life environment in their decisions and conclusions.