Zink A et al. (2006) Effectiveness of tumor necrosis factor inhibitors in rheumatoid arthritis in an observational cohort study: comparison of patients according to their eligibility for major randomized trials. Arthritis Rheum 54: 3399–3407

Randomized controlled trials (RCTs) are the gold standard for evaluating new treatments; however, RCTs often exclude patients with comorbidities, concomitant medications, particular dosing schemes and disease states, so their settings are artificial. An observational cohort study has now found that patients who fulfill the inclusion criteria for the RCTs that led to approval of tumor necrosis factor (TNF) inhibitors for the treatment of rheumatoid arthritis (RA) reflect only a small proportion of patients treated with TNF inhibitors in practice. The study also showed that patients with RA who would not have been eligible for these RCTs could benefit from anti-TNF therapy.

The study included registry data from 1,458 participants in RABBIT, a German observational cohort study that monitors patients with RA who initiate treatment with any licensed biologic agent. Laboratory and clinical outcomes were assessed at baseline and 6 months. Patients were analyzed according to their eligibility (or lack thereof) for inclusion in the five major RCTs of TNF inhibitors.

In this cohort, only 21–33% of patients would have been eligible for inclusion in one of the major RCTs, but the absolute response rates to TNF inhibitors were comparable in patients who would and who would not have been eligible for the major RCTs. The authors conclude that RCTs need not be so restrictive in their inclusion criteria.