Session Title: Health Services Research: Improving Clinical Practice
Session Type: Abstract Submissions (ACR)
To conduct a cost-effectiveness analysis from a health system perspective of various strategies in managing chronic gout to mitigate risk of allopurinol-induced Stevens-Johnson Syndrome and Toxic Epidermal Necrolysis, including three that utilize results of HLA-B*5801 genetic testing.
A decision tree model was developed to estimate costs and quality-adjusted life years (QALYs) over 20-year horizon for patients with chronic gout who fulfil the criteria for initiating ULT with either allopurinol or probenecid. Strategies modelled were: (a) Standard ULT with allopurinol as first-line drug (ULT); (b) Standard ULT with allopurinol as 1st line drug coupled to a safety programme (ULT+SP) that monitors for signs of SJS/TEN; (c) HLA-B*5801 genetic testing-guided ULT treatment (G->ULT) in which choice of 1st line ULT is based on test results (probenecid for test positive, allopurinol for test negative) and avoidance of allopurinol in HLA-B*5801 positive patients; (d) genetic testing to enrol test positive patients in a safety programme when initiating allopurinol (G->SP); test negative patients would receive allopurinol without SP; (e) HLA-B*5801 genetic guided ULT with the safety programme (G->ULT->SP) in which test positive patients are initially given probenecid, but non-responders are subsequently switched to allopurinol in the presence of the safety programme; (f) No ULT and treatment of acute flares only (no ULT). Although inputs are based on the Singapore context, the model is a general template that can be readily adapted to other populations and countries.
No ULT and treating acute flares only has the lowest QALYs and highest costs. Compared with standard ULT, G->ULT increases cost by US$910 but reduces QALYs, despite the reduction in SJS/TEN risk. ULT+SP has an incremental cost-effectiveness ratio (ICER) of US$102,030/QALY compared to ULT alone. G->SP achieves the same QALYs as ULT+SP but at higher cost. G->ULT->SP results in an ICER of $93,030/QALY compared to standard ULT. (Figure 1 and 2)
Standard care with allopurinol as first line treatment for chronic gout without genetic testing remains the optimal strategy from a cost-effectiveness perspective based on a threshold of US$50,000/QALY. A safety programme for all patients is not cost-effective, but may become so if implementation costs decrease. If genetic testing costs decrease, testing may become cost-effective if results are used to guide the selection of 1st line ULT, with allopurinol as 2nd line ULT for HLA-B*5801 positive patients in the presence of a safety programme.
W. C. Tan-Koi,
G. G. Teng,
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ACR Meeting Abstracts - https://acrabstracts.org/abstract/role-of-hla-b5801-genetic-testing-and-a-safety-programme-when-initiating-allopurinol-therapy-for-chronic-gout-management-a-cost-effectiveness-analysis/