A Cross-sectional Study Comparing Pulmonary Function and Exercise Capacity in Posttuberculosis Sequelae Patients among Smokers and Nonsmokers

INTRODUCTION: Post-tuberculosis (TB) lung disease is a major cause of long-term respiratory morbidity despite microbiological cure. Smoking may exert an additional detrimental effect on pulmonary function and exercise capacity in these patients; however, comparative data between smokers and nonsmokers remain limited. The study aimed to evaluate and compare pulmonary function and exercise capacity among pulmonary TB sequelae patients between smokers and nonsmokers. METHODS: This hospital-based cross-sectional study was conducted in the Department of Pulmonary Medicine at a tertiary care hospital in Chengalpattu District, Tamil Nadu, India, from June 2024 to November 2025. A total of 110 post-TB patients (55 smokers and 55 nonsmokers) were included. Ethical approval was obtained from the Institutional Human Ethics Committee (IEC No. 994/24; dated April 22, 2024), and written informed consent was obtained. Pulmonary function was assessed using spirometry (forced expiratory volume in 1 s [FEV1], forced vital capacity [FVC], FEV1/FVC, peak expiratory flow rate [PEFR]), and functional capacity was evaluated using the 6-min walk test and Modified Borg Dyspnea Scale. Data were analyzed using SPSS version 29, with P < 0.05 considered statistically significant. RESULTS: The majority of participants were aged 40-60 years, with no significant age difference between the groups (P = 0.593). Smokers were predominantly male (87.3%) compared to nonsmokers (P < 0.001). Underweight status was more common among smokers (23.6% vs. 9.1%, P = 0.019). Smokers demonstrated significantly lower FEV1 (P = 0.027), FEV1% predicted (P = 0.001), FEV1/FVC ratio (P = 0.009), and PEFR (P < 0.001). Obstructive ventilatory defects were more common among smokers (43.6% vs. 23.6%, P = 0.028). Six-minute walk distance was significantly lower in smokers (398.2 ± 63.0 m) compared to nonsmokers (441.6 ± 58.5 m) (P < 0.001), and Borg dyspnea scores were significantly higher (P < 0.001). CONCLUSION: Smoking significantly worsens pulmonary function and exercise capacity in patients with post-TB sequelae, acting as an additive risk factor for long-term respiratory impairment. Integration of smoking cessation and pulmonary rehabilitation into post-TB care is essential.