In Brief | Infectious Diseases & Endocrinology
INFECTIOUS DISEASES: How Accurate Are Symptom and Chest X-ray Screening for TB in People with Diabetes?
28 October 2026
Study Snapshot
| Design | Diagnostic accuracy study using baseline data from a prospective cohort; single primary care diabetes clinic |
| Population | 673 adults with diabetes enrolled consecutively at Site B Community Health Centre, Khayelitsha, Cape Town (March–November 2022); 661 included in the analysis. Median age 53 years; 63.8% female; 17.4% HIV positive; 83.4% with HbA1c ≥ 7% |
| Tools Assessed | Any cough; any TB symptom (cough, fever, night sweats, or weight loss); chest X-ray read by two physicians (TB-suggestive or any lung abnormality); computer-aided reading (CAD4TB, threshold ≥ 60); and symptoms and chest X-ray combined |
| Reference Standard | Single sputum sample tested by Xpert Ultra in all participants, regardless of symptoms or chest X-ray findings (trace results counted as positive in the primary analysis) |
| Primary Outcome | Sensitivity and specificity of each screening tool; TB diagnosed in 9 participants (1.4%, 95% CI 0.6–2.6%), all HIV negative |
Summary
WHO recommends systematic TB screening for people with diabetes in high-burden settings, but the accuracy of the recommended tools in this population has been poorly understood.
In this South African study, every participant was asked about TB symptoms, had a chest X-ray, and provided a sputum sample for Xpert Ultra testing, regardless of their screening results. Of the 661 participants analysed, nine were diagnosed with TB.
Symptom screening identified few of these cases. Asking about cough detected only two of the nine (sensitivity 22.2%), although it rarely flagged people without TB (specificity 97.5%). Broadening the questions to include fever, night sweats, or weight loss detected no additional cases and slightly increased false positives (specificity 96.0%).
Chest X-ray performed better. Physician-read X-rays showing abnormalities suggestive of TB detected five of the nine cases (sensitivity 55.6%) while correctly clearing 95.4% of those without TB, and a positive X-ray was more likely to reflect true TB than any other screening result. Computer-aided reading (CAD4TB) produced the fewest false positives (specificity 97.7%) but detected fewer cases than physician reading (sensitivity 37.5%). Combining symptom screening with chest X-ray detected no additional cases.
Chest X-ray specificity was significantly lower in participants with previous TB. Symptom-screening specificity remained consistent across glycaemic control, HIV status, sex, and age.
The authors conclude that symptom-based screening has limited value in people with diabetes, and that chest X-ray improves sensitivity but remains suboptimal, with reduced specificity in those with previous TB. They state that the high TB prevalence observed calls for further exploration of additional screening tools that are both feasible and cost-effective. Because only nine TB cases were identified, the sensitivity estimates were imprecise, and the authors note that the findings need to be validated in other settings.
References
Disclaimer & Fact-Checking Policy
Disclaimer. This is a summary of published research and does not replace the original study or local treatment guidelines. Every effort has been made to attribute quotes and content correctly. Where possible, all information has been independently verified. The Medical Education Network bears no responsibility for any inaccuracies which may occur from the use of third-party sources. AI may have been used to assist in preparing this summary. All efforts have been made to validate the content against the original material; however, inaccuracies may occur. The Medical Education Network urges all practitioners to review the original material as their clinical reference. The Medical Education Network bears no responsibility where these summaries are used as a proxy for the original research. If you have any queries regarding this article contact us
Fact-checking Policy. The Medical Education Network makes every effort to review and fact-check the articles used as source material in our summaries and original material. We have strict guidelines in relation to the publications we use as our source data, favouring peer-reviewed research wherever possible. Every effort is made to ensure that the information contained here accurately reflects the original material. Should you find inaccuracies or out-of-date content or have any additional issues with our articles, please make use of the Contact Us form to notify us.
