Table 1:

Model inputs

Description	Base-case value	Min	Max	Distribution	References
IBS therapy
TCA responder rate	48.9%	40.0%	50.0%	Binomial Probability: 66/135 N: 135	Drossman, et al. (2003)18
TCA discontinuation rate	29.6%	15.0%	36.4%	Binomial Probability: 40/135 N: 135	Drossman, et al. (2003)18
Rifaximin responder rate	40.7%	40.0%	50.0%	Binomial Probability: 254/624 N: 254/624	Pimentel, et al. (2011)42
Rifaximin discontinuation rate	6.6%	0.0%	10.0%	Binomial Probability: 41/625 N: 625	Pimentel, et al. (2011)42
Rifaximin retreatment interval	17.3 weeks	10 weeks	52 weeks		Lembo, et al. (2016)32 Pimentel, et al. (2011)19
QALYs
Health utility associated with therapeutic response	0.78	0.77	0.83		Spiegel, et al. (2009)13
Health utility associated with therapeutic non-response	0.73				Spiegel, et al. (2009)13
Costs
Cost of office-based electrocardiogram	$41.00	$35.00	$150.00		Healthcare Bluebook43
Cost of amitriptyline 25mg pill	$0.21974				Medicaid NADAC Database2
Cost of rifaximin 550mg pill	$29.78				Medicaid NADAC Database2
Work-days lost per year	6.0	2.4	88.4	Triangular	Drossman, et al. (1993)44 Hahn, et al. (1999)45 Hungin, et al. (2003)46 Hungin, et al. (2005)47
Average daily 2016 US wage	$177.44	$0.00	$300.00		US Bureau of Labor Statistics48
Cost of admission related to IBS ICD-9 diagnosis in 2014, discounted forward to 2016 at 3% rate	$5,973.93				HCUPnet49
Annual hospitalization rate with poorly controlled IBS-D	10.0%	0.0%	20.0%		Buono, et al. (2016)50
Cost of office visit for IBS-D (HCPCS 99214)	$108.20				Center for Medicare and Medicaid Services Physician Fee Schedule51
Number of office visits per year associated with poorly controlled IBS-D	3.5	0.0	7.0		Buono, et al. (2016)50

IBS = irritable bowel syndrome; TCA = tricyclic agent; QALY = quality adjusted life year; ICD = International Classification of Diseases; US = United States; IBS-D = irritable bowel syndrome with diarrhea; HCPCS = Healthcare Common Procedure Coding System