Matching-adjusted indirect comparison of adalimumab vs etanercept and infliximab for the treatment of psoriatic arthritis.

OBJECTIVES

No head-to-head trial has compared the efficacy of adalimumab vs etanercept and infliximab for psoriatic arthritis (PsA). This study implements a matching-adjusted indirect comparison technique to address that gap.

METHODS

Patient-level data from a placebo-controlled trial of adalimumab (ADEPT) were re-weighted to match average baseline characteristics from pivotal published trials of etanercept and infliximab. ADEPT patients were re-weighted by odds of enrollment in comparator trials, estimated using logistic regression. Matched-on characteristics included PsA duration, age, gender, severity, active psoriasis, and concomitant treatment. After matching, placebo-adjusted treatment arms were compared at weeks 12 (or 14) and 24. Outcomes included ACR20/50/70, PsARC, HAQ, and modified TSS. PASI50/75/90 were compared for patients with active psoriasis. Cost per responder (CPR) was assessed in the US and Germany using matching-adjusted end-points and drug list prices. Statistical significance was assessed using weighted t-tests.

RESULTS

After matching, adalimumab-treated patients had greater placebo-adjusted rates of ACR70 and PASI50/75/90 at week 24 compared with etanercept (all p < 0.05). Adalimumab patients had a higher placebo-adjusted rate of ACR70 than infliximab at week 14 (p = 0.034). Adalimumab treatment had lower CPR for ACR70 and PASI50/75/90 compared with etanercept at week 24, in both the US and Germany (all p < 0.02). Adalimumab had lower CPR than infliximab for all outcomes at week 24 (all p < 0.05).

CONCLUSION

Adalimumab is associated with higher ACR70 and PASI50/75/90 response rates than etanercept at week 24 and a higher ACR70 response rate than infliximab at week 14. Adalimumab has significant advantages over etanercept and infliximab in CPR across multiple end-points.

KEY LIMITATIONS: The matching-adjusted indirect comparison method cannot account for unobserved differences in patient characteristics across trials, and only a head-to-head randomized clinical trial can fully avoid the limitations of indirect comparisons. CPR findings are limited to the US and German markets, and may not be generalizable to other markets with different relative pricing.