Who
Adult and adolescent people with trace-positive sputum Xpert Ultra results (PWTS) identified during routine TB diagnostic evaluations. A total of 311 participants were enrolled: 170 in Uganda and 141 in South Africa. Median age was 37 years, 50% were male, and 57% had HIV.
What
The study evaluated how many PWTS had clinically or microbiologically evident tuberculosis within 3 months.
By the 3-month composite reference standard, 145/301 participants had TB: 48% (95% CI, 43%–54%). By microbiological criteria, TB prevalence was 26% at baseline and 41% by 3 months. By culture alone, baseline prevalence was 20%, and 3-month culture-confirmed prevalence was 30% among evaluable participants.
TB was associated with:
- Advanced HIV: CD4 <200 cells/mm³; PR 2.0 (95% CI, 1.2–3.3)
- TB symptoms: PR 3.1 (95% CI, 1.5–7.8)
- No recent TB history; recent TB was inversely associated with TB: PR 0.6 (95% CI, 0.3–0.9)
Repeat Ultra positivity or trace positivity was strongly associated with TB. Patient characteristics alone classified 3-month composite TB status with an AUC of 0.76, increasing to 0.80 with chest X-ray and 0.79 with CRP.
The authors concluded that TB prevalence among PWTS is high, supporting treatment for many patients, but that up to half may not have evident TB after systematic evaluation and follow-up. Treatment deferral may be reasonable in selected lower-risk patients when close follow-up is feasible.
When
Recruitment occurred from February 2022 to July 2024 in Uganda and November 2022 to June 2024 in South Africa. Participants with uncertain TB status were reassessed at 1 month and 3 months. The analysis focused on TB diagnosed within 3 months, interpreted as prevalent disease.
Where
The study was conducted at 7 health facilities in Kampala, Uganda, and outpatient clinics of Harry Gwala Regional Hospital and its catchment area near Pietermaritzburg, South Africa.
Why
The study aimed to clarify TB disease status among people with trace-positive sputum Ultra results, a group in whom the clinical significance of trace results may be uncertain. The objective was to estimate TB prevalence within 3 months and identify patient characteristics and ancillary tests associated with TB disease.
How
This was a prospective cohort study. Eligible participants underwent systematic baseline evaluation within 14 days of the initial trace Ultra result, including interview, physical examination, digital chest X-ray, repeat sputum Ultra, sputum cultures, HIV testing, CRP measurement, and additional tests in selected subgroups or sites.
Participants who remained untreated after baseline evaluation were reassessed at 1 and 3 months with repeat clinical assessment, sputum Ultra, sputum culture, CRP, and repeat chest X-ray at 3 months.
Treatment decisions were made by local clinicians and physician panels. Outcomes were classified using composite, microbiological, and culture reference standards. Analyses included prevalence estimation, univariate and multivariable regression, and ROC curve assessment.
Level of evidence: prospective observational cohort; moderate strength for estimating prevalence and associations, but not designed to establish causal effects.
Key limitations: Not all trace-positive patients were enrolled, many non-enrolled patients were missed due to distance or inability to contact, treatment decisions were clinician-dependent, and some diagnostic procedures differed by country.
Source: Visek C, Dalmat RR, Nalutaaya A, Erisa KC, Biché P, Stein G, Ganguloo A, Draper R, Nantale M, Shapiro AE, Wilson D. Prevalence and Predictors of Tuberculosis in Adults and Adolescents With Sputum Trace Ultra Results in 2 High-Burden Clinical Settings. Clinical Infectious Diseases. 2026 Mar 20:ciag019. https://benangmerah.net/record/78/