Impact and Cost-Effectiveness of Culture for Diagnosis of Tuberculosis in HIV-Infected Brazilian Adults

Background

Culture of Mycobacterium tuberculosis currentlyrepresents the closest “gold standard” fordiagnosis of tuberculosis (TB), but operational data are scant on theimpact and cost-effectiveness of TB culture for human immunodeficiency(HIV-) infected individuals in resource-limited settings.

Methodology/Principal Findings

We recorded costs, laboratory results, and dates of initiating TB therapyin a centralized TB culture program for HIV-infected patients in Rio deJaneiro, Brazil, constructing a decision-analysis model to estimate theincremental cost-effectiveness of TB culture from the perspective of apublic-sector TB control program. Of 217 TB suspects presenting betweenJanuary 2006 and March 2008, 33 (15%) had culture-confirmedactive tuberculosis; 23 (70%) were smear-negative. Amongsmear-negative, culture-positive patients, 6 (26%) began TBtherapy before culture results were available, 11 (48%)began TB therapy after culture result availability, and 6(26%) did not begin TB therapy within 180 days ofpresentation. The cost per negative culture was US$17.52(solid media)–$23.50 (liquid media). Per 1,000TB suspects and compared with smear alone, TB culture with solid mediawould avert an estimated eight TB deaths (95% simulationinterval [SI]: 4, 15) and 37 disability-adjustedlife years (DALYs) (95% SI: 13, 76), at a cost of$36 (95% SI: $25, $50)per TB suspect or $962 (95% SI:$469, $2642) per DALY averted. Replacing solidmedia with automated liquid culture would avert one further death(95% SI: −1, 4) and eight DALYs (95%SI: −4, 23) at $2751 per DALY (95%SI: $680, dominated). The cost-effectiveness of TB culturewas more sensitive to characteristics of the existing TB diagnosticsystem than to the accuracy or cost of TB culture.

Conclusions/Significance

TB culture is potentially effective and cost-effective for HIV-positivepatients in resource-constrained settings. Reliable transmission ofculture results to patients and integration with existing systems areessential.