Smoking, smoking cessation, and 7-year mortality in a cohort of Thai adults

Jiaying Zhao; Cha-Aim Pachanee; Vasoontara Yiengprugsawan; Sam-Ang Seubsman; Adrian Sleigh; Thai Cohort Study Team

doi:10.1186/s12963-015-0062-0

Smoking, smoking cessation, and 7-year mortality in a cohort of Thai adults

Popul Health Metr. 2015 Oct 27:13:30. doi: 10.1186/s12963-015-0062-0. eCollection 2015.

Authors

Jiaying Zhao¹, Cha-Aim Pachanee², Vasoontara Yiengprugsawan¹, Sam-Ang Seubsman³, Adrian Sleigh¹; Thai Cohort Study Team

Affiliations

¹ National Centre for Epidemiology and Population Health and Global Health Division, Research School of Population Health, The Australian National University, Canberra, Australia.
² International Health and Policy Program, Bureau of Policy and Strategy, Ministry of Public Health, Nonthaburi, Thailand.
³ National Centre for Epidemiology and Population Health and Global Health Division, Research School of Population Health, The Australian National University, Canberra, Australia ; School of Human Ecology, Sukhothai Thammathirat Open University, Nonthaburi, Thailand.

Abstract

Background: Smoking is a strong risk factor for mortality in both the developed and the developing world. However, there is still limited research to examine the impact of smoking cessation and mortality in middle-income Southeast Asian populations.

Methods: We use longitudinal data from a large Thai cohort of adult Open University students residing nationwide, linked with official death records to assess the association of smoking status and mortality risks during a 7-year follow-up. The log-rank test was used to evaluate the statistical probability of differential survival according to baseline smoking status. Multivariate hazard ratios (HR) were reported for smoking status and all-cause and cause-specific mortality.

Results: From 2005 baseline to 2012, current smokers were more likely to die than cohort members who ceased smoking and never smokers (1.9 vs 1.3 vs 0.6 %, p < 0.05). The hazard of all-cause mortality increased with the daily amount of cigarette consumption among both current and former smokers. Cause of death analyses showed that current male smokers had a significantly increased risk of cardiovascular disease related mortality (HR 3.9 [95 % CI 1.8-8.1]). Former male smokers had a moderate increase in risk of dying from cardiovascular diseases compared to never smokers (HR 1.6 [95 % CI 0.7-3.4]). Current male smokers between 2005 and 2009 experienced highest subsequent mortality hazards during the period 2009-2012 compared to never smokers (HR 2.1 [95 % CI 1.4-3.4]). The higher risk of dying reduced if people quit smoking during the 2005-2009 follow-up period (HR 1.5 [95 % CI 0.7-3.3]). Risk for mortality fell even further among long-term quitters (HR 1.4 [95 % CI 0.9-2.2]).

Conclusion: Among a large nationwide cohort of Thai adults, current smokers were at a significantly and substantially higher risk of all-cause mortality, especially cardiovascular-related mortality. The higher risk of dying fell if people quit smoking and the risk for mortality was even lower among long-term quitters. Promotion of smoking cessation will contribute substantially to the reduction in avoidable mortality in Thailand.

Keywords: Cardiovascular diseases; Cessation; Mortality; Smoking; Thailand; Tobacco.