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- vs. sputum-based testing among people (≥13 years) with presumptive TB at primary health centers in Vietnam and Zambia. The BWS assessed sixteen TB test features, including accuracy, sample type, turnaround time, cost, and service aspects. We analyzed preferences using Hierarchical Bayes modeling and identified distinct preference groups using Latent Class Multinomial Logit analyses (LCA). Results: Among 409 participants enrolled, 356 (87%) met quality criteria for analysis. When asked directly, most participants preferred providing tongue swabs over sputum (58% vs 29%, p<0.001; 13% no preference). In the BWS exercise, tongue swab was also preferred over sputum (mean rescaled preference weight [MPW] 6.4 [95%CI: 5.9-6.8] vs. 5.0 [95%CI: 4.6-5.4]). However, support and counseling (MPW=14.0), sensitivity (MPW=12.3), specificity (MPW=10.2), and provider attitude (MPW=7.4) were the most important features overall. Less important features included facility opening hours (MPW=3.4) and the influence of trusted sources on testing decisions (MPW=2.2). LCA identified five distinct preference groups, but support and counseling were universally valued. Participants in Groups 2 (27.3%; n=97) and 3 (17.1%; n=61) valued tongue swabs over many other features. Group 5 participants (11%; n=39) strongly valued sputum-based testing. 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.

The authors have declared no competing interest.

Funding for this study was provided by the Bill and Melinda Gates Foundation, award number INV-058789 and the R2D2 TB Network, which was supported by the National Institute of Allergy and Infectious Diseases of the National Institutes of Health under award number U01AI152087.

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The details of the IRB/oversight body that provided approval or exemption for the research described are given below:

The study was approved by the Research Ethics Committee of the Hanoi Lung Hospital in Vietnam [# 935/BVPHN-HĐĐĐ], the University of Zambia Biomedical Research Ethics Committee [# 4041-2023], the National Health Research Authority-Zambia [# NHREB002/15/07/2023], and the Ethics Committee of the Heidelberg University Hospital [#S-519/2023]. All adult participants provided informed consent prior to the survey in their preferred language. For those under 18 years of age, informed consent of the legal guardian/caretaker and assent was obtained from participants.

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