PMS12 Number Needed to Treat (NNT), Cost Per Responder (CPR) and Budget Impact (BI) of TNF Inhibitors (TNFi) in the Treatment of Psoriatic Arthritis (PSA)

Abstract

Estimate the NNT, CPR and U.S. BI of TNFi in PsA, using clinical assumptions from an independent National Institute for Health and Clinical Excellence (NICE) systematic review. Comparative data were sourced from a February 2011 NICE systematic review and Bayesian indirect comparison of adalimumab (ADA), etanercept (ETA) and infliximab (IFX) in PsA. Primary outcomes included Psoriatic Arthritis Response Criteria (PsARC) and Psoriasis Area and Severity Index (PASI) 75% response. NICE adjusted outcomes for each TNFi at 12 or 14 weeks vs a standardized placebo response, within each outcome, and these acute results were projected to 52 weeks. Based on this data, this analysis applied biologic costs from January 2012 Wholesale Acquisition Costs and labeled dosing over 52 weeks to derive NNT, CPR and BI. NICE reported results from six trials, deemed patient characteristics across trials consistent and assessed quality of all trials as good. The authors of the independent NICE review stated that across all outcomes of joint and skin disease at 12 weeks, IFX was associated with the highest probabilities of response. These expected placebo-adjusted response rates were as follows – PsARC: ADA (33.8%), ETA (46.4%), IFX (54.6%); PASI 75: ADA (43.4%), ETA (13.3%) and IFX (72.5%). This analysis then derived that 52-week CPR was lowest for IFX for all outcomes. Also, for PASI 75, NNT to achieve 100 responders was 230.9, 751.9 and 137.9 for ADA, ETA and IFX respectively, with corresponding annual biologic costs to achieve 100 responders of $5.75M; $17.69M and $3.33M. In this analysis of projected 52 week relative outcomes and expected biologics costs, the incremental annual budget required to achieve 100 PASI 75 responders would be $2,422,816 or $14,360,355 greater if patients were initiated on ADA or ETA respectively, instead of IFX.