Research Square
Comparing MiniDock MTB, chest radiography, and symptoms for tuberculosis screening: a community-based evaluation in Karachi, Pakistan
By Eman Ku, Jackson YL, Qureshi SA and 4 others.
Abstract
Abstract Background Community-based active case finding (ACF) for tuberculosis (TB) is constrained by limited access to chest X-ray (CXR) and reliance on sputum-based diagnostic testing. Recently, WHO recommended near point-of-care testing which offers a non-sputum alternative, tongue swab (TS). We evaluated the feasibility and screening performance of MiniDock MTB on TS compared with WHO four-symptom screening (W4SS) and CXR in Pakistan. Methods We conducted 49 screening camps in underserved communities of Karachi. All adolescents and adults (> 10 years) underwent screening via W4SS, CXR, and TS collection. Individuals screening positive by any method were asked to provide sputum for Xpert MTB/RIF Ultra, sputum swab testing on MiniDock MTB, and mycobacterial culture. A microbiological reference standard (MRS) was defined as a positive Xpert MTB/RIF Ultra and/or mycobacterial culture. Results Overall, 4,303 individuals were screened (median age 28 years [IQR 16–40]); 38% were female. All participants had CXR and W4SS screening results, while 3,432 (79.8%) had valid TS results. Overall, 752 participants were screen-positive for TB, including 606 with valid TS results. TS was positive in 19/3,432 (0.4%), CXR in 302/4303 (7.0%) and W4SS in 522/4,303 (12.1%). Sputum was collected from 243 (32%) of 752 screen-positive participants, including 225 (37%) with valid TS results; Among 30 MRS-positive individuals, 29 had abnormal CXR, 14 had symptoms and 13 a positive TS result. CXR showed the highest sensitivity (96.7%; 95% CI 82.8–99.9), compared with W4SS (46.7%; 95% CI 28.3–65.7) and TS testing (46.4%; 95% CI 27.5–66.1). Conclusion TS testing, although feasible, was not sufficiently sensitive to function as a standalone TB screening test. Further optimization of specimen collection, assay performance, and evaluation in diverse settings is needed to better define the role of TS testing in community-based TB screening.
