The value of persistence in treatment with subcutaneous TNF-alpha inhibitors for ankylosing spondylitis

Objective To estimate the impact of persistence on cost-effectiveness of subcutaneous tumor necrosis factor-alpha inhibitors (SC-TNFis) from healthcare and societal perspectives in a United Kingdom ankylosing spondylitis (AS) population using a recently published Markov cohort model. Methods A recently published cost-effectiveness model developed for a National Institute for health and Care Excellence appraisal was extended to fit the current study; in brief, it is a Markov cohort model where treatment responders continue from the trial period with maintenance SC-TNFi treatment, while non-responders transition to conventional care. Costs and effects were modeled for a hypothetical SC-TNFi with average efficacy and price. Model outcomes included quality-adjusted life-years (QALYs), total direct and indirect lifetime costs, and incremental cost-effectiveness ratios (ICERs). The cost-effectiveness of SC-TNFi persistence was estimated by decreasing the annual discontinuation probability in five percentage point increments from 25 to 5% per annum. Results From a health care perspective, the ICERs for the modeled discontinuation rates compared to the baseline annual discontinuation rate (25%) ranged between GBP 17,277 and GBP 18,161. From a societal perspective, increased discontinuation rates resulted in decreased total costs and higher QALYs; hence, lower discontinuation rates dominated higher discontinuation rates from a societal perspective. Conclusion In conclusion, this study shows that, all else equal, higher SC-TNFi treatment persistence in AS is cost effective from a health care perspective and dominant from a societal perspective. Hence, all else equal, prescribing the SC-TNFi with the highest persistence may be considered a cost-effective strategy.