Association of inactive pulmonary tuberculosis lesions with the risk of active disease development in the elderly: a population-based retrospective study.

Background: Individuals with inactive pulmonary tuberculosis (PTB) lesions were found to be high-risk populations for active PTB development. This retrospective study evaluated the association between different types of inactive PTB lesions and the development of active PTB aiming to provide epidemiological evidence for developing precise intervention strategies. Methods: Based on a population-based PTB active-case-finding project conducted on the elderly, 154 028 subjects who had participated in the 2020 baseline survey were included in the current analysis. Results: During the 2-year follow-up, 462 cases developed microbiologically confirmed active PTB with an overall incidence rate of 0.19 per 100 person-years. Among the study population, 15 037 (9.76%) showed chest radiography (CXR) abnormalities suggestive of inactive PTB, which was found to be independently associated with an increased risk of active PTB with an adjusted hazard ratio (aHR) of 6.00 (95% confidence interval (CI) 4.85-7.43) compared with normal CXR. Such a relationship was consistently observed for inactive lesions, including fibrosis, calcification, pleural thickening and nodule lesions with aHRs ranging from 2.94 to 6.55. Inactive PTB lesions alone or a history of anti-tuberculosis (TB) treatment alone were independently associated with the risk of active PTB with aHRs of 6.96 (95% CI 5.59-8.67) and 7.67 (95% CI 4.26-13.78), respectively. A combined effect between inactive PTB lesions and with history of anti-TB treatment was found with an aHR of 10.50 (95% CI 5.93-18.52). Conclusion: Overall, individuals with inactive PTB lesions, regardless of lesion type and history of anti-TB treatment, are at increased risk of developing active PTB and deserve interventions for TB control.