High relative risk of all-cause mortality attributed to smoking in China: Guangzhou Biobank Cohort Study

Abstract

Background: Prediction of disease burden from smoking in China based on earlier cohorts in China Mainland could under estimate the disease burden at the current stage. No cohort studies in China focused specifically on people born since 1950. We examined the risk of all-cause mortality attributed to smoking in adults in Guangzhou, the city with the most rapidly expanding economy in China Mainland. Material: The population-based Guangzhou Biobank Cohort included 21,658 women and 8,284 men aged 50+ years enrolled from 2003-2008 and followed till January 2016. Smoking status was assessed at baseline interview. Vital status and causes of deaths were ascertained by record linkage. Results: During an average follow-up of 8.8 (standard deviation=1.8) years, 2,986 (1,586 women, 1,400 men) deaths were recorded. In those born in 1920-1939, 1940s and 1950s, after adjustment for confounders, the hazard ratio (HR) (95% confidence interval (CI)) of all-cause mortality in current versus never smokers was 1.73 (95% CI 1.53-1.95), 2.00 (95% CI 1.71-2.34) and 3.89 (95% CI 2.74-5.51) (p for trend 0.02) in men, and 1.36 (95% CI 1.03-1.78), 2.00 (95% CI 1.18-3.37) and 5.89 (95% CI 1.87-18.53) in women, respectively. In men and women together, the adjusted HRs in those born in 1920-1939, 1940s or 1950s increased from 1.61 (95% CI 1.45-1.80) to 2.02 (95% CI 1.74-2.34), and 4.40 (95% CI 3.14-6.17) (P for trend 0.009). We found no evidence that the risks varied by sex (p for sex interaction from 0.18 to 0.94). Conclusions: In smokers born after 1949 in Guangzhou and other areas which have the longest history of smoking, the relative risk of mortality could have reached three-fold that of non-smokers, as in the UK, US and Australia. The high relative risk, if confirmed, would mean many more than 1 million deaths attributable to smoking in 2010 in China.