Faculty of Health Sciences, Federal University of Grande Dourados, Dourados, Mato Grosso do Sul, Brazil.
School of Nursing, State University of Mato Grosso do Sul, Dourados, Mato Grosso do Sul, Brazil.
Clin Infect Dis. 2022 Jul 6;74(12):2115-2121. doi: 10.1093/cid/ciab847.
Although systematic tuberculosis screening in high-risk groups is recommended by the World Health Organization (WHO), implementation in prisons has been limited due to resource constraints. Whether Xpert Ultra sputum pooling could be a sensitive and efficient approach to mass screening in prisons is unknown.
In total, 1280 sputum samples were collected from incarcerated individuals in Brazil during mass screening and tested using Xpert G4. We selected samples for mixing in pools of 4, 8, 12, and 16, which were then tested using Ultra. In each pool, a single positive sample of differing Xpert mycobacterial loads was used. Additionally, 10 pools of 16 negative samples each were analyzed as controls. We then simulated tuberculosis screening at prevalences of 0.5-5% and calculated the cost per tuberculosis case detected at different sputum pooling sizes.
The sensitivity and specificity of sputum pooling were high (sensitivity: 94%; 95% confidence interval [CI]: 88-98; specificity: 100%, 95% CI: 84-100). Sensitivity was greater in pools in which the positive sample had a high mycobacterial load compared to those that were very low (100% vs 88%). In settings with a higher tuberculosis prevalence, pools of 4 and 8 were more efficient than larger pool sizes. Larger pools decreased the costs by 87% at low prevalences, whereas smaller pools led to greater cost savings at higher prevalence at higher prevalences (57%).
Sputum pooling using Ultra was a sensitive strategy for tuberculosis screening. This approach was more efficient than individual testing across a broad range of simulated tuberculosis prevalence settings and could enable active case finding to be scaled while containing costs.
尽管世界卫生组织（WHO）建议对高危人群进行系统性结核病筛查，但由于资源限制，监狱中的实施情况有限。尚不清楚 Xpert Ultra 痰混合检测是否可以作为监狱大规模筛查的一种敏感、高效的方法。
在巴西的大规模筛查中，共收集了 1280 份被监禁者的痰液样本，并用 Xpert G4 进行检测。我们选择了 4、8、12 和 16 个样本的混合池，然后用 Ultra 进行检测。在每个池子里，使用具有不同 Xpert 分枝杆菌载量的单一阳性样本。此外，还分析了 10 个各包含 16 个阴性样本的混合池作为对照。然后，我们模拟了 0.5-5%的结核病流行率，并计算了不同痰混合量检测到每个结核病病例的成本。
痰混合检测的敏感性和特异性都很高（敏感性：94%；95%置信区间[CI]：88-98；特异性：100%，95%CI：84-100）。阳性样本具有较高分枝杆菌载量的混合池比载量非常低的混合池的敏感性更高（100%比 88%）。在结核病流行率较高的情况下，4 和 8 个样本的混合池比更大的混合池效率更高。在低流行率下，较大的混合池降低了 87%的成本，而在高流行率下，较小的混合池可以节省更多成本（57%）。
使用 Ultra 的痰混合检测是一种敏感的结核病筛查策略。在广泛的模拟结核病流行率设置下，这种方法比个体检测更有效，并且可以在控制成本的同时，扩大主动发现病例的规模。
