Mortality and morbidity burden associated with smoking: evidence from a 1.6 million cohort in Hong Kong

Existing evidence on the disease burden of smoking is often outdated and incomprehensive, particularly in Asia, which plays a pivotal role in the global tobacco control community. This study aimed to provide an updated and comprehensive estimate of the mortality and morbidity burden associated with smoking in Hong Kong.

This retrospective cohort study included adults with smoking status information recorded in the Hong Kong Hospital Authority database between 1 January 2008 and 31 December 2012. Subjects were classified into never-smokers, ex-smokers, and current smokers. The primary outcome was all-cause mortality. Cox proportional hazards regression, adjusted with fine stratification weighting and key baseline characteristics, yielded hazard ratios (HRs) with 95% confidence intervals (CIs) for each outcome.

Of the 1,571,065 individuals analyzed, there were 14.3% current smokers, 11.9% ex-smokers, and 73.8% never-smokers. After a median follow-up of 11.7 years, 61,198 current smokers, 45,918 ex-smokers, and 220,947 never-smokers died. Significantly higher risks of all-cause mortality were observed among current smokers (HR [95% CI]: 1.53 [1.51-1.56]) and ex-smokers (1.33 [1.31-1.35]) than among never-smokers. Current and ex-smoking were positively associated with the incidences of 76 and 60 out of 115 morbidities, respectively. Strong associations were observed between smoking and increased risks of suicide (intentional self-harm), mental, and behavioral disorders due to psychoactive substance use and alcohol use, particularly among current smokers. Notably, these risks were higher in females than in males for all three outcomes. Additionally, females demonstrated higher risks of all-cause mortality, pneumonia, chronic obstructive pulmonary disease, and asthma compared to males.

Smoking remains a substantial burden on the healthcare system in Hong Kong, which may still be underestimated due to Hong Kong's relatively less advanced stage in the tobacco epidemic compared to some Western countries, where the full hazards of smoking have already manifested more prominently.