Estimating the prevalence of Positive Tuberculin Skin Test Reactions in General Population and High-risk Groups: A Meta-analysis

Abstract

Results of tuberculin skin test (TST) surveys among different populations have been reported in many studies as a method for detecting primary Mycobacterium tuberculosis infection. Combining these results provides reliable estimates of primary latent tuberculosis (TB) infection for health
policymakers. This study aims to estimate the prevalence of latent TB infection in general and high‑risk populations in Iran. National and international databanks were searched using specifc keywords. After restricting the search strategy, duplicates exclusion, reviewing titles, abstracts and full texts, and quality assessment, eligible papers were selected. The heterogeneity between the results was assessed according to Cochrane and I‑squared indices. The prevalence of positive TST reactions was estimated using fxed and random effect models. Totally, 33 papers were entered into the meta‑analysis reporting the TST results in 12693 people aged over 18. The prevalence (95% confdence intervals) of positive TST reactions in all groups, general population, health staff, medical students, household close contacts, patients with TB, immunocompromised patients, HIV/AIDS patients, and those with risky behaviors was 26.2% (19.6–32.8), 25.4% (4.8–46.1), 38.9% (27.4–50.9), 13.4% (9.9–16.7), 35.9% (16.4–55.5), 13.7% (8.4–18.9), 29.4% (21.2–37.7), and 14.6% (3.9–25.3), respectively. Our study showed great varieties of positive TST results among different Iranian subpopulations. Furthermore, the prevalence of latent TB infection among health professionals and family members of TB patients was considerably different from that of the other subgroup. Since TB control programs such as active case fnding are routinely conducted among household close contacts and HIV/AIDS cases, other high‑risk groups including health‑care workers and immunocompromised patients should be taken into consideration in these preventive programs.

Keywords: Latent tuberculosis, purifed protein derivative, tuberculin skin test, tuberculosis