Researchers from the University of Cape Town and University College London have reported that commonly used tuberculosis screening methods may fail to detect a substantial number of cases among individuals with diabetes. The study, titled "Sensitivity and specificity of tuberculosis screening tools in people with diabetes," appeared in PLOS Global Public Health. It formed part of BALANCEprep, a preparatory phase for the UCT-sponsored BALANCE trial, which aims to improve TB prevention strategies for diabetic populations.
According to AllAfrica, the investigation included 673 adults receiving routine diabetes care at the Site B Community Health Centre in Khayelitsha, South Africa. Every subject received a symptom check and a chest X-ray, while sputum samples were taken for molecular testing irrespective of initial findings. Among the 661 participants with valid molecular results, nine tested positive for TB, representing a prevalence of 1.4%. The data indicated that symptom screening, which included cough, fever, night sweats, and weight loss, identified only 22% of these cases. Chest X-rays performed better, detecting 56% of cases, but still missed nearly half. Additionally, chest X-rays showed lower specificity among participants who had previously had TB, which could lead to extra tests.
Professor Molebogeng Rangaka, the study's senior author from UCT and UCL, noted that current methods might not be adequate for diabetics, especially when relying solely on symptoms. She highlighted the need for more precise screening strategies, such as molecular testing that does not depend on symptoms or X-ray abnormalities. Dr Yohhei Hamada, the first author and a clinical research fellow at UCL, acknowledged that the small number of diagnosed cases introduces uncertainty to the sensitivity estimates. He stated that larger studies are needed to confirm these findings and identify feasible screening methods for routine healthcare settings.
The research builds on existing evidence that diabetics face two to three times the risk of developing TB compared to those without the condition. The World Health Organization currently recommends systematic TB screening for diabetics in high-burden settings like South Africa, though much of the supporting evidence comes from general population studies. As diabetes prevalence rises in the region, improving detection in this high-risk group is considered critical for strengthening TB prevention and control efforts.