Smoking and Tuberculosis among the Elderly in Hong Kong

Abstract

A cohort of 42,655 clients that were first registered with the Elderly Health Service in 2000 were followed prospectively through the tuberculosis (TB) notification registry until the end of 2002. A total of 286 active TB cases (186 culture confirmed) were identified. The annual TB notification rates were 735, 427, and 174 per 100,000 among current smokers, ex-smokers, and never-smokers, respectively (p < 0.001). The trend in TB risk persisted after the control of background characteristics using Cox proportional hazards analysis (adjusted hazard ratios [HRs]: 2.63, 1.41, and 1, p < 0.001). In comparison with never-smokers, current smokers had an excess risk of pulmonary TB (adjusted HR, 2.87; 95% confidence interval [CI], 2.00-4.11; p < 0.001), but not extrapulmonary TB (adjusted HR, 1.04; 95% CI, 0.33-3.30; p = 0.95). Among the current smokers, those who developed TB smoked more cigarettes per day than those who did not (13.43, SD 8.76 vs. 10.96, SD 7.87, p = 0.01). A statistically significant dose-response relationship was observed with respect to active TB and culture-confirmed TB (both p < 0.05). Smoking accounted for 32.8% (95% CI, 14.9-48.0%), 8.6% (95% CI, 3.3-15.1%), and 18.7% (95% CI, 7.7-30.4%) of the TB risk among males, females, and the entire cohort, respectively. Approximately 44.9% (95% CI, 20.7-64.6%) of the sex difference was attributable to smoking.

A study of gender differentials in the prevalence of tuberculosis based on NFHS-2 and NFHS-3 data

“…Some worldwide studies(78) have shown that males are having higher risk factors like smoking, alcoholism and drug addiction to get tuberculosis than females. In one of the study from Hong Kong, Leung et al .…”

“…In one of the study from Hong Kong, Leung et al . (7) has mentioned that smoking accounted for 32.8% [95%CI,14.9-48.0%], 8.6% [95%CI,3.3-15.1%] and 18.7% [95CI,7.7-30.4%] of the TB risk among males, females and the entire cohort, respectively. In comparison to never- smokers, current smokers had an excess risk of pulmonary tuberculosis TB [adjusted HR 2.87,95%CI,2.00-4.11, P <0.001].…”

Limited impact of tuberculosis control in Hong Kong: attributable to high risks of reactivation disease

“…Several factors could have contributed to high reactivation risks in Hong Kong compared to the United Kingdom : nutrition (likely to have been unsatisfactory in Hong Kong prior to 1950) ; smoking (peaked during the 1970s in Hong Kong compared the 1950s in the United Kingdom and Western populations, although the overall consumption was similar in the two settings [21][22][23]) ; genetics (if tuberculosis arrived recently in South East Asia, then the prevalence of susceptibility genes for tuberculosis disease may still be high [24]) ; predisposing co-infections or environmental conditions (e.g. silicosis, which is a strong risk factor for tuberculosis [25], was the second most commonly notified occupational disease during the 1990s in Hong Kong [26]) ; or the pathogen itself (most of the isolates of M. tuberculosis found among Asian tuberculosis cases belonged to the Beijing family of strains [27,28], although its association with the risks of developing disease remains unclear).…”

Factors affecting smear conversion in tuberculosis management

“…Likewise, smoking was reported to be associated with late sputum smear or culture conversion, after 2 months of anti-tuberculosis treatment [20,21]. In a past clinical trial on immunotherapy with M.vaccae in the treatment of pulmonary tuberculosis by Durban…”