Cost effectiveness of biologic therapies for plaque psoriasis

During the last decade, the implementation of biologic agents has changed the therapeutic management of severe psoriasis. Biologic agents have clinically proven efficacy, but their use is associated with a much higher cost compared with traditional treatment options. Therefore, when assessing the use of these drugs for the treatment of psoriasis, it is important to consider their cost effectiveness.

The objective of this study was to determine and compare the cost effectiveness of biologic agents with regard to the cost per patient achieving a minimally important difference (MID) in the Dermatology Life Quality Index (DLQI) and the cost per patient achieving a 75% improvement in the Psoriasis Area Severity Index (PASI-75).

A PubMed literature search was conducted to identify studies describing the efficacy of all currently US FDA-approved biologic therapies. The cost effectiveness of each agent over a 12-week period was determined and a sensitivity analysis was performed. Based on clinical efficacy at 12 weeks, treatment paradigms were extrapolated to estimate cost-effectiveness ratios after 1 year of treatment. Pooled data on each biologic agent at different doses were compared in a one-way sensitivity analysis and in an extreme case scenario analysis.

Twenty-seven studies were included in the analysis. Intravenous (IV) infliximab 3 mg/kg was the most cost-effective biologic agent with respect to both the cost per patient achieving PASI-75 and the cost per patient achieving a DLQI MID. The next most cost-effective agents in terms of cost per patient achieving PASI-75 were subcutaneous (SQ) adalimumab 40 mg administered every other week (eow) after an 80-mg loading dose, SQ adalimumab 40 mg eow, and IV infliximab 5 mg/kg. In terms of cost per patient achieving DLQI MID, IV infliximab 5 mg/kg, SQ etanercept 25 mg once weekly, SQ etanercept 50 mg once weekly, and SQ adalimumab 50 mg eow after an 80-mg loading dose were the next most cost-effective agents behind IV infliximab 3 mg/kg. For both costs per patient achieving DLQI MID and PASI-75, alefacept was the least cost-effective agent up to a 10% level of variation at all doses except 0.025 mg/kg once weekly.

This study was limited by the use of efficacy data from 12-week clinical trials that did not compare treatments head to head to determine relative efficacy and may not be generalizable to longer treatment periods. Additionally, the estimated cost of treatment did not take into account indirect costs or variations in costs due to insurance company price contracting.

Biologic treatments that were most cost effective were so in respect to both the cost per patient achieving DLQI MID and per patient achieving PASI-75. This suggests that the same agents that are effectively clearing the disease are also effective in improving the patients' subjective assessment of dermatology-related quality of life.