Quantifying sputum production success during community-based screening for TB

Quantifying sputum production success during community-based screening for TBDear Editor, Systematic screening or active case-finding (ACF) can reduce TB prevalence in high-burden settings, 1 but the limitations of sputum-based diagnostic algorithms are a perceived barrier to widespread implementation. 2Current approaches typically identify high-risk individuals using non-sputum-based tests, such as symptom screening or chest X-ray (CXR), but subsequently require sputum-based molecular testing.The collection and provision of sputum samples is often difficult, 3,4 and some large-scale screening efforts have successfully collected sputum from only a minority of eligible individuals. 1Most data on sputum production comes from populations of symptomatic people seeking health care, particularly people with HIV. 5,6Quantifying the extent to which sputum collection is a barrier to systematic screening and understanding its variation between risk groups, can inform planning for TB screening efforts in different populations and motivate the development of nonsputum-based TB diagnostics. 7Therefore, we examined the willingness and ability of individuals to produce expectorated sputum in a large communitybased ACF effort in Uganda.We conducted CXR-based TB screening in peri-urban Uganda as part of a pragmatic cluster-randomized trial of ACF (Clinicaltrials.gov:NCT05285202).Ongoing since June 2022, this analysis considers data through to February 29, 2024.All non-pregnant participants 15 years old, symptomatic or not, were offered CXR, with analysis by computer-aided detection (CAD:qXR, Qure.ai) in real-time.Participants with qXR scores above a specified threshold (initially set at 0.5, lowered to 0.1 by November 2022) were immediately requested to provide an expectorated sputum specimen for Xpert MTB/RIF Ultra (Cepheid, Sunnyvale, CA, USA) testing.Pregnant participants were asked for sputum without CXR.Participants were instructed to take two deep breaths, then cough, and provide at least 2 ml of expectorated sputum.Participants who struggled to expectorate were coached using an active cycle of breathing technique (ACBT). 8If they were still struggling, they were asked to try jogging and drinking water.No sputum induction was offered.Participants who could not provide sputum were referred to a local health facility for further evaluation.We estimated the proportion of participants with abnormal CXR who declined or failed to produce sputum.We categorized eligible participants by whether they attempted but were unable to expectorate (Group 1), declined to provide