Preferences for tongue swab-based versus sputum-based testing in the context of TB care: a best-worst scaling exercise in Vietnam and Zambia

Background The development of non-sputum-based tests is an urgent priority to increase access to tuberculosis (TB) diagnostic testing. Understanding preferences of people undergoing testing is critical for designing tests and strategies aligned with their needs. Methods We conducted a survey and best-worst scaling (BWS) exercise to determine relative preferences for tongue swab-based versus sputum-based testing among people (≥13 years) with presumptive TB at primary health centres in Vietnam and Zambia. The BWS assessed 16 TB test features, including accuracy, sample type, turnaround time, cost and service aspects. We estimated mean rescaled preference weights, our primary outcome, using Hierarchical Bayes modelling and identified distinct preference groups using latent class multinomial logit analyses (LCA). Results Among 409 participants enrolled, 356 (87%) met quality criteria for analysis. The median age of participants was 39 years (IQR 29-47), and most were female (60.7%). When asked directly, most participants preferred providing tongue swabs over sputum (58.1% vs 28.7%, p Conclusions Participants in Vietnam and Zambia preferred tongue swab-based TB testing over sputum. However, sample type was less important than test accuracy and other TB care features affecting the testing experience.