UBC Theses and Dissertations
Economic evaluations in the context of treatment recommendations in spondyloarthritis : analyses from the DESIR cohort Harvard, Stephanie
Spondyloarthritis (SpA) is an inflammatory disease comprising both ankylosing spondylitis and non-radiographic axial SpA. This thesis conducted four studies using data from DESIR, a longitudinal cohort of 708 French SpA patients, focusing on economic questions in the context of SpA treatment recommendations. The objectives of study 1 were to value health resource use and productivity loss among DESIR patients and identify factors associated with costs. Cost valuation was done using public data and factors associated with costs were identified in multivariate regression models. This study showed that anti-TNF agents were the greatest cost driver in DESIR and generated the cost outcomes necessary to perform economic evaluations using DESIR data. The objective of study 2 was to collaborate with rheumatologists to develop measurable definitions of adherence to SpA treatment recommendations. A Delphi survey was conducted with 15 rheumatologists, who developed measurable definitions for 6/11 recommendations. The study uncovered differences of opinion between rheumatologists and generated the classification system necessary to explore adherence to recommendations among DESIR patients. The objective of study 3 was to examine the effect of adherence to anti-TNF use recommendations on outcomes in DESIR. Employing alternate definitions of adherence, patients were classed as adherent anti-TNF users, non-adherent anti-TNF users, adherent non-users, and non-adherent non-users. Following one potential definition, non-adherent anti-TNF users had significantly increased non-biologic costs compared to adherent users, while non-adherent non-users had significantly worse health outcomes than adherent anti-TNF users. This study showed that the impact of adherence to anti-TNF recommendations is sensitive to the definition of adherence and highlighted the need to validate methods to measure adherence. The objective of study 4 was to explore whether the French anti-TNF access restrictions are the most cost-effective in that setting relative to other potential restrictions. Five separate datasets were created comprising DESIR patients satisfying different sets of anti-TNF access criteria. Incremental cost-effectiveness ratios (ICERs) associated with anti-TNF use were calculated in each subset in basecase and sensitivity analyses. A sensitivity analysis simulating a 24-week stopping rule among anti-TNF non-responders demonstrated the effect of non-response on anti-TNF cost-effectiveness. The study underscored the need for evidence-informed anti-TNF access restrictions.
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