Relationship between smoking and spontaneously healed pulmonary TB on chest radiography in a South Korean population

SETTING: The Korea National Health and Nutrition Examination Survey is a national, population-based, cross-sectional surveillance programme.OBJECTIVE: 1) To investigate the prevalence of spontaneously healed pulmonary tuberculosis (SHPTB) on chest radiographs (CXRs) in South Korea, as well as its demographic and clinical associations, and 2) to determine the relationship between SHPTB and smoking.DESIGN: People with normal findings on CXRs (n = 24 190) and those with SHPTB (n = 1863) were compared in univariate, bivariate and multivariate analyses with respect to smoking and demographic and clinical factors.RESULTS: The prevalence of SHPTB was 7.2%. The proportion of patients with SHPTB tended to be higher in males, people of older age, ever smokers, as well as people with low body mass index and low education level. In bivariate analysis, after adjustments for age and sex, SHPTB was found more often among ex-smokers (P = 0.005) and current smokers (P = 0.024) than in non-smokers. Multivariate analyses revealed increased relative odds for SHPTB with increased age (P < 0.001), male sex (P < 0.001) and ex-smoker status (P = 0.016). Passive smoking was also significantly associated with SHPTB (P = 0.022).CONCLUSION: In addition to increasing the risk of active TB and negatively affecting the outcome of TB treatment, smoking is also associated with SHPTB, as detected on CXRs.