P790 Assessing the cost-effectiveness of Epstein–Barr virus screening in young men initiating combination therapy with infliximab and azathioprine for Crohn's disease. (16th January 2018) - Fennimore, B
Abstract: Background: Primary Epstein–Barr virus (EBV) infection is associated with developing hemophagocytic lymphohistiocytosis (HLH) with azathioprine use with infliximab (IFX+AZA) but not infliximab monotherapy (IFXm). Experts recommend EBV antibody (EBVAb) screening in young patients and avoiding AZA in EBVAb negative patients. We aimed to assess the impact of an EBV screening strategy in young men with Crohn's disease (CD). Methods: We constructed a Markov model to assess the cost-effectiveness of an EBVAb screening strategy among 16- to 26-year-old males with severe CD initiating biologic therapy. We compared two strategies: (1) EBVAb testing (EBVt): after EBVAb testing, EBVAb positive individuals started IFX+AZA, while EBVAb negative individuals started IFXm, and (2) Standard of care (SOC): all individuals initiated IFX+AZA without screening. In strategy (2), age-specific EBV status was modelled, increasing in prevalence from 59% (age 16) to 100% (age 26). EBV negative individuals were exposed to a 4% annual risk of EBV infection, resulting in an HLH risk of 0.29/1000 person-years with AZA. Age-, gender-, and AZA use-specific lymphoma was modelled using SEER and CESAME data. In both strategies, IFX failures transitioned to adalimumab. We derived transition probabilities from controlled trials, and utilities and costs from the literature, Medicare data, and wholesale acquisition costs. Mean costs, quality adjusted life years (QALYs), and incremental cost-effectiveness ratios (ICERs) were calculated via First-order Monte Carlo simulation of 50 trials of 100000 individuals at ages 16 to 26. The time horizon was 1 year. Willingness-to-pay (WTP) thresholds of $50000 and $100000 were assessed. Results: Prior to age 26, the SOC strategy yielded greater QALYs but increased costs at 1 year compared with EBVt (Table 1). With a WTP threshold of $50000, EBVt was preferred in those under age 23 (Figure 1). However, with a WTP threshold of $100000, combination therapy was preferred for all ages. Over 50 trials of 100000 individuals, 6 cases of HLH occurred. Conclusions: Based on this model, a societal EBVAb testing strategy minimises the risk of HLH but negatively impacts quality of life, likely secondary to reduced use of combination therapy. While costs are also reduced, the SOC strategy would remain preferred with a WTP of $100000 when compared with EBVt.