[The association between smoking and sputum smear-positive pulmonary tuberculosis in Osaka City]

This study aimed to analyze and evaluate the association between tuberculosis (TB) and smoking in order to obtain basic information for the control of smoking.

Of the 637 patients with sputum smear-positive pulmonary tuberculosis who were newly registered in Osaka City in 2009, 581 patients whose smoking status was identified were selected as study subjects. Data on the following were collected: patient characteristics, presence or absence of underlying conditions, patient's delay and doctor's delay in the diagnosis of TB, presence or absence of cavities, and degree of smear positivity. The patients were divided into the following three groups according to their smoking status: (1) never smokers (those who have never smoked), (2) former smokers (those who had smoked, but quitted), and (3) current smokers (those who smoke currently).

(1) PATIENT CHARACTERISTICS: The subjects consisted of 413 males and 168 females, with mean ages of 65.7, 55.4, and 70.2 years for never smokers, current smokers, and former smokers, respectively. (2) Comparison with the national adult smoking rate (National health and nutrition survey 2009, Ministry of Health, Labour and Welfare): The prevalence of current smoking among male patients with sputum smear-positive pulmonary TB in Osaka was 62.4-82.4% among men in their 20s to 60s, and 27.5% among men in their 70s, which is higher than the national average. For female patients, the prevalence of current smoking was 46.2% among women in their 20s and 45.5% among women in their 30s, which is clearly higher than the national average. This was also true for those aged 40 years or older. (3) Severity of TB disease and smoking status: The presence of a cavity was significantly associated with being a male patient, being a current smoker, and longer patient's delay. Sputum smear grades (2+) and (3 +) were significantly correlated with being under 59 years old, being a current smoker, and longer patient's delay.

The prevalence of current smokers was significantly higher among sputum smear-positive pulmonary TB patients in Osaka than the national average. More smokers had cavitary lesions and a high degree of smear positivity, which may lead to poorer treatment outcomes, and may also expose more surrounding people to infection.