Abstract
BackgroundBoth smoking and diabetes can increase the risk and influence the manifestations and outcomes of tuberculosis (TB). It is not clear whether the influence of smoking on pulmonary TB differs between non-diabetic and diabetic patients. Herein, we assessed the manifestations and outcomes of TB in relation to smoking in both diabetic and non-diabetic TB patients.Methodology/Principal FindingsAll diabetic culture-positive pulmonary TB patients notified from 2005–2010 at three teaching hospitals in Taiwan were enrolled. A culture-positive pulmonary TB patient without DM who was notified to the health authority immediately prior to each diabetic TB patient was selected for comparison. The 972 patients in this study cohort included 365 (37.6%) non-diabetic non-smokers, 149 (15.3%) non-diabetic smokers, 284 (29.2%) diabetic non-smokers, and 174 (17.9%) diabetic smokers. The adjusted relative risk of a pretreatment positive smear for a smoker compared with a non-smoker was 2.19 (95% CI 1.38–3.47) in non-diabetic patients and 2.23 (95% CI 1.29–3.87) in diabetic culture-positive pulmonary TB patients. The adjusted relative risk for a positive smear among diabetic smokers was 5.61 (95% CI 3.35–9.41) compared with non-diabetic non-smokers. Smoking was significantly associated with an increased frequency of bilateral lung parenchyma involvement (AdjOR 1.84, 95% CI 1.16–2.93), far-advanced pulmonary TB (AdjOR 1.91, 95% CI 1.04–3.50), cavitary lesions (AdjOR 2.03, 95% CI 1.29–3.20), and unfavorable outcomes of TB (AdjOR 2.35, 95% CI 1.02–5.41) in non-diabetic patients. However, smoking was not associated with cavitary lung parenchyma lesions regarding the location, number or size of the cavity in diabetic TB patients.Conclusions/SignificanceSmoking and diabetes have joint effects on a pretreatment positive smear. Diabetic smokers had more than a 5-fold increased risk of a pretreatment positive smear than did non-diabetic non-smokers, indicating remarkable joint effects of diabetes and smoking on the risk of TB transmission.
Highlights
Smoking is significantly associated with increased risks of tuberculous infection, tuberculosis (TB) disease, TB mortality and recurrent TB [1,2,3,4,5]
As the non-diabetic culture-positive pulmonary TB patients were systematically selected, this was a representative sample of all non-diabetic culture-positive pulmonary TB patients who were treated at the three teaching hospitals from 2005–2010, which enabled us to assess the influence of smoking on pulmonary TB in relation to diabetes
In a multinomial logistic regression analysis stratified by diabetes and adjusted for age and sex, the adjusted relative risk of pretreatment positive smears for smokers compared with non-smokers was 2.19 in non-diabetic and 2.23 in diabetic culture-positive pulmonary TB patients
Summary
Smoking is significantly associated with increased risks of tuberculous infection, tuberculosis (TB) disease, TB mortality and recurrent TB [1,2,3,4,5]. It has been reported that diabetic TB patients have more symptoms [15], are more likely to be smear-positive [16, 17], and have an increased frequency of cavitary lesions [18] compared with non-diabetic TB patients. The World Health Organization (WHO) and the International Union Against Tuberculosis and Lung Disease (The Union) have encouraged National TB Programme to address the combined challenges of smoking, diabetes and TB [19, 20]. Both smoking and diabetes can increase the risk and influence the manifestations and outcomes of tuberculosis (TB). We assessed the manifestations and outcomes of TB in relation to smoking in both diabetic and non-diabetic TB patients
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