Cost-effectiveness of different tuberculosis diagnostic approaches in Nigeria based on decision analytical modelling

Tuberculosis (TB) remains a leading cause of morbidity and mortality in Nigeria, particularly among people living with HIV (PLWH), who face significantly higher risks of developing active TB. Conventional diagnostic methods such as sputum smear microscopy and chest radiography often fail to detect TB accurately in this population due to smear-negative presentations and atypical radiographic findings. Recent diagnostic innovations, including the Xpert MTB/RIF Ultra, TB lipoarabinomannan (TB-LAM) and TB loop-mediated isothermal amplification (TB-LAMP) tests, offer improved sensitivity and specificity, but their cost-effectiveness in resource-limited settings remains unclear.

In this economic evaluation, we combined a decision tree with cost-effectiveness analysis to compare three TB diagnostic algorithms tailored for PLWH in Nigeria: (1) Xpert MTB/RIF Ultra following chest radiography (chest X-ray; CXR), (2) TB-LAM following CXR and (3) TB-LAMP following CXR. Data on test accuracy, costs and TB prevalence were obtained from systematic reviews and meta-analyses, with costs adjusted for inflation and local purchasing power. We estimated the incremental cost-effectiveness ratios (ICERs) for the three diagnostic approaches. Sensitivity analyses were conducted to assess the robustness of results across varying input parameters.

TB/LAM was found to be the most cost-effective option at a cost of US$17 per TB case detected when compared with US$20 and US$22 per TB case detected for the baseline strategy of Xpert MTB/RIF Ultra and TB-LAMP, respectively. These ICERs are consistent with willingness-to-pay thresholds set at three times Nigeria's gross domestic product (GDP) and remained robust over a wide range of costs and epidemiological parameter inputs.

Among PLWH in Nigeria, the TB-LAM algorithm represents the most cost-effective diagnostic strategy. However, the Xpert MTB/RIF Ultra may provide additional value in settings with sufficient infrastructure and funding. This study underscores the need for tailored diagnostic approaches that balance accuracy, scalability and affordability to enhance TB detection and management in vulnerable populations.