Pooling sputum samples for TB testing using Xpert MTB/RIF Ultra: an innovative cost-effective and efficient approach to enhance access, equity, and coverage of TB-care among poor communities at risk

Xpert MTB/RIF Ultra is a rapid diagnostic tool for tuberculosis (TB) and rifampicin resistance. However, its high-cost challenges programmatic operational use in low-resourced settings, where it’s needed the most due to the high burden of TB. This urges for innovative solutions to improve the cost-effectiveness of TB diagnosis. Therefore, here we investigate accuracy and reliability of a sputum samples pooling testing approach using Xpert MTB/RIF Ultra to expand the community-based TB diagnosis. A cross-sectional study was conducted on sputum samples collected from TB-suspected individuals. Initially, samples were tested individually using Xpert MTB/RIF Ultra, followed by retesting pool samples after each four samples were pooled together following pre-established guidelines. Data were analyzed to measure and evaluate the specificity, sensitivity, negative predictive value (NPV), positive predictive value (PPV), and the cost and time savings of this pooling strategy. A total of 1,380 sputum samples were included in this study. Our analysis showed that pooled testing for TB was effective, identifying 110 (7.9%) positive cases. This method had high accuracy with 97.5% agreement, 98.1% specificity, 90.4% sensitivity, 77.3% positive predictive value (PPV), and 99.3% negative predictive value (NPV). It also reduced costs by 51.8% (from 12,472 RwF (~ $10.32) to 6005 RwF (~ $4.97) per sample tested) and cut testing time by 38.4% (from 2.50 to 1.54 h per sample tested). A significant difference in CT values before and after pooling was found (p = 0.00704), though the effect size was small (Cohen’s d = 0.307), indicating limited interpretation implication. This study demonstrates that the samples-pooling approach using Xpert MTB/RIF Ultra significantly reduces both costs and testing time in operational settings. This offers a great opportunity to expand the access to molecular TB diagnostic services enhancing health equity among at risk populations in low resources settings. This saving in cost and time, if used properly it will improve quality and accessibility of other health services through integration and resources sharing, particularly during this era of funding cut. The cost-effectiveness of this approach will significantly facilitates implementing community surveys to test seemingly health yet at high-risk asymptomatic individuals.