Tuberculosis screening of travelers to higher-incidence countries: A cost-effectiveness analysis

Tan, Michael; Menzies, Dick; Schwartzman, Kevin

doi:10.1186/1471-2458-8-201

BMC Public Health

Table 2 Model assumptions

From: Tuberculosis screening of travelers to higher-incidence countries: A cost-effectiveness analysis

	Base value	Range	Sources
Annual risk of progression from latent tuberculosis (LTBI) to TB disease
Among persons newly infected during travel
First two years after infection	0.025	0.02 – 0.05	[33]
Subsequently	0.001	0.001 – 0.002	[34]
Among persons with LTBI before travel, given
No underlying radiographic abnormalities [see below]	0.001		[34]
Underlying radiographic abnormalities [see below]	0.0066		[34]
Reduction in risk afforded by:
Full 9 months of isoniazid, given drug-sensitive latent infection	90%		[35]
<6 months isoniazid	0%		[36]
Previous LTBI, among persons who are reinfected during travel	79%		[37]
Prevalence of isoniazid resistance
Mexico	0.072	0.072 – 0.12	[38, 39]
Dominican Republic	0.198	--	[40]
Haiti	0.159	--	[41]
Active TB
Proportion of travelers with active TB symptomatic upon return	0.27	0.11 – 0.44	[21, 26]
Probability of hospitalization given active TB diagnosed after symptoms	0.8		[42]
Probability of hospitalization given active TB diagnosed through screening	0.5		[21, 22]
Probability of completing full anti-TB therapy	1.0		assumed
Risk of major side effect with full anti-TB therapy	0.051	0.01 – 0.1	[43]
Probability of death, given major treatment side effect	0.015	0.001 – 0.032	[43–45]
Treatment of latent TB infection
Probability of completing 9 months isoniazid	0.647	0.62 – 1	[10, 46]
Probability of major side effect with isoniazid	0.003		[43–45]
Probability of death, given major treatment side effect	0.015	0.001 – 0.032	[43–45]
Tuberculin skin testing
Probability of boosting, given previous BCG vaccination	0.25		[17]
Specificity for LTBI	0.875	-	[17]
Sensitivity for LTBI	0.99	-	[47, 48]
Sensitivity for active TB	0.88	-	[48]
Probability of loss to follow-up between pre- and post- travel evaluations, for repeat testing strategies	0.34		[7]
Probability of abnormal chest X-ray upon return from travel
With preexisting LTBI	0.11	0.07 – 0.15	[33, 34, 49, 50]
With LTBI newly acquired during travel	0		assumed
With active TB	0.95	0.9 – 1	[51, 52]
Sputum cultures (3) for M. Tuberculosis
Specificity	0.99		[51]
Sensitivity	0.9		[53]
Costs for TB screening and care in the US (expressed in 2005 US dollars)
Initial clinic visit	$68		[54, 25]
Tuberculin skin test	$12		[42, 23]
Follow-up clinic visit after tuberculin test	$36		[42]
Chest radiograph with reading	$36		[42]
Isoniazid, 9 months supply	$25		[54]
7 outpatient clinic visits during isoniazid treatment	$385		[54]
Major adverse reaction to isoniazid	$9,834		[54]
3 sputa for AFB smear and culture, after abnormal CXR	$126		[55, 56]
Inpatient treatment of active TB disease	$9,061		[57]
Outpatient treatment of active TB disease	$2,600		[42]
Contact investigation and management, per active TB case (identified via screening)	$4,483		[42, 24]

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ISSN: 1471-2458

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