Efficacy and effectiveness of tumour necrosis factor inhibitors in the treatment of rheumatoid arthritis in randomized controlled trials and routine clinical practice.

Objective: Efficacy of TNF inhibitors in the treatment of RA assessed in randomized controlled trials (RCTs) may not be fully comparable to routine care owing to the stringent inclusion criteria. The objective of this study was to observe the effectiveness of TNF inhibitors in real-world patients and assess the patients' potential eligibility for the RCTs.

Methods: RA patients starting a TNF-inhibitor treatment between 2004 and 2014 were identified from the National Register for Biologic Treatment in Finland, which is a longitudinal observational cohort study. Effectiveness was measured using the ACR and EULAR response criteria and by studying the proportion of patients reaching DAS28 remission. The patients' baseline characteristics were compared against the inclusion criteria of 27 RCTs.

Results: EULAR moderate and good treatment responses at 6 months were achieved by 69 and 40% of the users of the first TNF inhibitor, respectively. ACR20, ACR50 and ACR70 responses were reached by 48, 27 and 13%, respectively. DAS28 remission was reached by 47%. Only 7.6-44% of the patients would have been potentially eligible for the RCTs. The eligible patients had better treatment responses compared with the non-eligible patients. Different TNF inhibitors were mostly equipotent, but the usage of MTX co-therapy had a major influence on treatment response.

Conclusion: Only a small proportion of patients would have been eligible for RCTs, and the efficacy of TNF inhibitors assessed in them cannot be generalized directly into Finnish routine health care.