Economic burden of smoking: evidence from a 1.6 million cohort in Hong Kong.

BACKGROUND: Declining in smoking prevalence may not correlate with reduced economic burden. This study aimed to estimate Hong Kong's economic burden of smoking using actual territory-wide public healthcare expenditure data. METHODS: This retrospective cohort study included adult public healthcare service users in the Hong Kong Hospital Authority healthcare system, with recorded smoking status between 1 January 2008 and 31 December 2012, and follow-up until 31 December 2022. Participants were classified into never-smokers, ex-smokers or current smokers. Outcomes were costs associated with general and specialist outpatient clinics (GOPC, SOPC), accident and emergency services (A&E), and hospitalization. A generalized linear model with log link function and fine stratification weighting evaluated differences in annual average costs per person for each healthcare service. RESULTS: Among the 1,571,065 individuals analyzed, 14.3% were current smokers, 11.9% ex-smokers, and 73.8% never-smokers. Smoking was associated with significantly higher annual average costs per person for SOPC, A&E, and hospitalization. Current smokers, compared to never-smokers, had a relative risk of 1.19 for SOPC, 1.40 for A&E, and 1.57 for hospitalization. Sex-specific analyses showed higher cost multipliers for women than men for SOPC, A&E and hospitalization. Additional annual cost of overall public healthcare services associated with smoking was projected at USD725.66 and USD336.30 million for current smokers and ex-smokers, respectively, accounting for 0.27% of Hong Kong's GDP and 7.46% of total healthcare expenditures in 2023. CONCLUSIONS: Smoking imposes substantial economic burdens in Hong Kong despite its low smoking prevalence. Accurate estimation of this burden is critical for advancing tobacco control measures.