Table 1. Input parameters.

Parameters	Base case	Range (min-max)	Source(s)
Epidemiological data
Incidence of allopurinol-induced SJS/TEN in Thai population	0.0016	0.00079–0.00241	[26]
Prevalence of HLA-B*5801 in Thai population	0.15	0.12–0.18	[27], [28] a
Probability of death among SJS/TEN	0.1134	0.0503–0.1765	[26]
Probability of DES in SJS/TEN patients	0.3760	0.2882–0.4704	[6]
Test characteristics
Sensitivity	1.000	NA	DMSC
Specificity	1.000	NA	DMSC
Gene-disease association
Association between HLA-B*5801 and allopurinol-induced SJS/TEN in Thai population	348.33	19.15–6336.88	[8], [20]
Costs (THB, year of costing: 2013)
Direct medical care costs
Annual cost of SJS/TEN management	15440.275	339.40–129492.25	[38]
Cost of HLA-B*5801 testing	1,000	800–1,200	DMSC
Annual drug cost of allopurinol	411.99	137.33–823.99	[39]
Annual drug cost of probenecid (alternative)	1,277.50	1,277.50–2,555.00	[39]
Annual cost of gout management	7,512	149–474,254	BCRH b
Annual cost of DES management	4,043.90	3,235.12–4,852.68	Expert
Direct non-medical care costs
Cost of transportation for patient with SJS/TEN	151.93	121.54–182.32	[22], [38]
Cost of transportation for relative of patient with SJS/TEN	1,030.09	824.07–1,236.10	[22], [38]
Cost of additional food for relative of patient with SJS/TEN	379.44	303.55–455.33	[22], [38]
Cost of transportation for patient with gout	1,194.63	1,004.09–1,385.16	[22]
Cost of additional food for relative of patient with gout	440.06	385.03–495.08	[22]
Cost of transportation for patient with DES	607.72	486.18–729.26	[22]
Cost of additional food for relative of patient with DES	223.86	179.09–268.63	[22]
Outcomes
Life expectancy of Thai population (at 30 years old)	42.7	-	[41]
Utility value of patient with gout	0.71	0.638–0.736	[31]
Utility value of patient with gout and dry eye syndrome	0.48	0.40–0.56	[31]–[33] c
Discount rate (% per year)	3	0–6	[42]

^aData from meta-analysis.

^bCalculated from Buddhachinaraj Regional Hospital (BCRH) database using ICD-10 for identification of patients.

^cCalculated from utility of patients with DES and utility of gout patients using multiplicative method.

SJS = Stevens-Johnson syndrome; TEN = toxic epidermal necrolysis; THB = Thai baht; DES = dry eye syndrome; DMSC = Department of Medical Sciences, Thailand.