Willingness to Pay for Human Leukocyte Antigen Type-B 58:01 Genetic Test to Prevent Allopurinol Hypersensitivity Syndrome in Gouty Patients: A Cross-sectional Survey in Thailand

Background: Since Thailand have high prevalence of Human Leukocyte Antigen Type-B* 58:01 (HLA-B*58:01) genotype. This genetic has strongly associated with allopurinol hypersensitivity syndrome (AHS). The national health security guideline of Thailand has accepted the association of HLA-B*58:01 genotype with prevention of AHS. The present study aims to investigate willingness to pay (WTP) of gouty patients for HLA-B*58:01 testing prior to starting allopurinol and factors influencing their decision for the testing. Methods: This study is a cross-sectional survey. The contingent valuation by open-ended questionnaire interview on WTP of gouty patients for HLA-B*58:01. The descriptive statistics are used. Participants who are age > 20 years, diagnosed based on the American College of Rheumatology/European League Against Rheumatism 2015 gout classification criteria at Naresuan university hospital (NUH), and three sub-district health promoting hospitals of NUH, Phitsanulok, Thailand are included. Results: Two hundred and fifty gouty patients are included. The majority of them are male, 214 patients (85.60%). The average age of the participants is 64.5 (± 12.8) years. Male patients are more WTP than female patients. The gouty patients with a monthly income between 10,001-30,000 Thai Baht (THB) (288.43-865.30 United states dollar (USD)) are the WTP patient group. The results show the majority of patients (64.2%) have WTP between 101-500 THB (2.88-14.42 USD) or average of median (IQR) is 500 (300, 800) THB or 14.37 8.62, 22.99) USD for the testing. The reason for decline the testing are the cost of the testing is too expensive. Other urate lowering agents, gouty patients have WTP for febuxostat, sulfinpyrazone and benzbromarone in 68%, 67.60% and 71.60%, respectively. Average WTP for febuxostat, sulfinpyrazone and benzbromarone 1,000 THB (28.74 USD), 1,000 THB (28.74 USD) and 285 THB (8.19 USD), respectively. Conclusion: The majority of gouty patients are willing to pay for the genetic testing even they have to pay for the testing cost themselves which is 1,000 THB (28.74 USD). They are willing to pay if they have to bear the cost of the testing themselves. For those un-WTP, the main reason is the cost of the genetic testing too expensive, followed by lack of income/low income. The maximum amount most participants are willing to pay for the testing is average of median (IQR) is 500 (300, 800) THB or 14.37 (8.62, 22.99) USD. This study may has affected to change a he