Xpert TB test very cost-effective in South Africans starting ART
Two Xpert Mycobacterium tuberculosis rifabutin resistance assays in South Africans starting antiretroviral therapy (ART) would be highly cost-effective, according to a cost-benefit modeling analysis using a hypothetical South African population.
Undiagnosed TB prevalence ranges from 15% to 30% among
HIV-positive people starting ART in regions with high TB
prevalence. These people are usually screened for TB by
symptoms and sputum smear, which have poor sensitivity for
detecting TB infection. To determine whether the Xpert test
and other approaches would prove cost-effective in screening
patients starting ART, researchers conducted this modeling
study.
The model considered all patients and only patients with TB
symptoms in hypothetical South African cohorts starting ART
with an average CD4 count of 171 cells/μL and TB prevalence
of 22%. The model simulated no active screening and four
diagnostic strategies: smear microscopy (sensitivity 23%);
smear and culture (sensitivity 100%); one Xpert test
(sensitivity in smear-negative TB 43%); two Xpert tests
(sensitivity in smear-negative TB 62%).
Because South Africa has a gross domestic product of $7100 per
capita, the researchers set that as the cutoff for determining
whether a diagnostic strategy is cost-effective.
Compared with no TB screening, screening symptomatic patients
with sputum smear would increase life expectancy by 1.6
months. Using two Xpert screens in all patients would increase
life expectancy by 6.6 months.
If TB prevalence is 22%, the incremental cost-effectiveness
ratio of sputum smear for all patients is $2800 per life-year
saved, while the incremental cost-effectiveness ratio for two
Xpert tests for all patients is $5100 per life-year
saved—well below the $7100 cost-effectiveness cutoff.
Using only one Xpert sample or only symptom screening was less
efficient.
The researchers conclude that their model-based analysis
“suggests that screening all individuals initiating ART
in South Africa with two Xpert samples is very
cost-effective.”
Source:
Jason R. Andrews, Stephen D. Lawn, Corina Rusu, Robin Wood,
Farzad Noubary, Melissa A. Bender, C. Robert Horsburgh, Elena
Losina, Kenneth A. Freedberg, Rochelle P. Walensky. The
cost-effectiveness of routine tuberculosis screening with
Xpert MTB/RIF prior to initiation of antiretroviral therapy: a
model-based analysis. AIDS. 2012; 26: 987-995.
For the study abstract
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abstract is free.)
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