Background Infliximab, adalimumab, etanercept and ustekinumab are indicated to treat moderate-severe plaque psoriasis in Europe.

Purpose To evaluate the relative efficacy of biological drugs in the maintenance phase in adults with moderate-severe plaque psoriasis in order in order to determinate if there are clinically relevant differences between the biological agents.

Materials and methods A systematic review of literature was conducted focused on the long-term efficacy.

The selection criteria of the studies were: health technology agencies reports, Bayesian network meta-analyses, systematic reviews, randomised controlled trials (RCTs), non-RCT, and observational studies in patients with moderate-severe plaque psoriasis treated with biologics at the doses approved by the EMA. Searches were realised in MEDLINE, EMBASE and the Cochrane Library and CRD databases until March 2013. The outcome evaluated was PASI (Psoriasis Area and Severity Index) 75.

Two authors independently selected the studies, assessed the quality, and performed the data extraction.

To assess the clinical relevance of the efficacy results (based on unadjusted indirect comparisons); as the ACCEPT study was the only RCT that directly compared two biological drugs in this population, a delta value of 14% was set. This value was regarded as the threshold for the maximum difference in clinical efficacy between two biologicals.

Results There was no direct evidence or adjusted indirect comparisons that compared the relative efficacy of these biological drugs.

A systematic review, two non-randomised studies, and a retrospective observational study were included.

61% (184/301), 79% (49/62), 65% (42/64), 59% (204/345) and 56% (42/76) of patients treated with infliximab, ustekinumab 90 mg, ustekinumab 45 mg, adalimumab, and etanercept 50 mg weekly achieved PASI 75 response, respectively in 50–72 weeks.

Regarding the clinical relevance of these results, and assuming the current limitations of the study designs, infliximab, ustekinumab 45 mg, adalimumab and etanercept 50 mg weekly could be considered similar.

Conclusions The available data on long-term treatment with biological agents is scarce and heterogeneous.

Biological drugs could be considered similar in terms of PASI 75 in the maintenance phase in patients with moderate-severe plaque psoriasis.

Conflict of interest: ownership of Amgen Inc stock.