Methods: We conducted a model-based cost-effectiveness analysis comparing two algorithms for TB screening and diagnosis at HIV clinics in Ethiopia: (1) a WHO-recommended symptom screen combined with Xpert for PLHIV with positive symptom screen; and (2) current recommended practice algorithm (CRPA), which includes sequential (a) WHO-recommended symptom screen, (b) smear microscopy for those with a positive symptom screen, and (c) clinical diagnosis and empiric treatment for selected patients with negative smear microscopy. Our primary outcome was US$ per disability-adjusted life year (DALY) averted. Secondary outcomes were additional true positive diagnoses with symptom screen/Xpert, and false negative and false positive diagnoses averted.
Results: Compared to CRPA, combining two WHO-recommendations—a WHO symptom screen with Xpert for those with a positive symptom screen—was highly cost effective for TB diagnosis among PLHIV (incremental cost of $21 per DALY averted). Among a cohort of 15,000 PLHIV with TB prevalence of 6%, this algorithm detected 54 more true positive cases than CRPA, and averted 2059 false positive and 54 false negative diagnoses. Per 15,000 patients, the WHO-recommended algorithm was modestly more costly ($252,000) than CRPA ($225,000). Cost-effectiveness of the symptom screen/Xpert algorithm was largely robust to sensitivity analyses.
Conclusion: In this model-based analysis, combining a WHO-recommended symptom screen with Xpert for TB diagnosis among PLHIV was highly cost-effective ($21 per DALY averted) and more sensitive and specific than CRPA in a high-burden, resource-limited setting. The high number of false positive diagnoses in CRPA was due to low specificity of both the WHO-recommended symptom screen and clinical diagnosis. High cost of symptom screen and Xpert will require additional resources for widespread scale up and implementation.
M. Tsegaye, None
R. Kempker, None
A. Aseffa, None
H. Blumberg, None