Clinical benefits of smoking cessation in reducing all-cause and disease-specific mortality among older people in Taiwan: A 10-year nationwide retrospective cohort study

Objective To investigate the relationship between smoking cessation and disease mortality risks among elderly Taiwanese. Methods We identified 1677 people aged 65 or above from the 2001 National Health Interview Survey in Taiwan (2001 NHIST) and linked with the 2000-2010 National Health Insurance Research Data (2000-2010 NHIRD) and 2001-2010 Death Registry. Subjects were classified into four groups: never smokers, current smokers, former smokers quitting less than 5 years and former smokers quitting at least 5 years. Information on medical history was drawn from 2000-2001 NHIRD. Cox proportional hazards models were used to analyze the smoking status and mortality risk. Results Over 10 years, incidences of all-cause death per person-year was 0.048 among the never smokers, 0.058 for current smokers and 0.057 for former smokers. Current smokers had higher risk of all-cause death (HR = 1.38, 95%CI = 1.13-1.68), all-cause cancers (HR = 1.85, 95%CI = 1.28-2.69), lung cancer (HR = 3.02, 95%CI = 1.56-5.85) and cardiovascular disease (HR = 1.71, 95%CI = 1.17-2.48) as compared to never smokers. Former smokers who quit smoking for < 5 years has higher mortality risk in lung cancer (HR = 3.89, 95%CI = 1.33-11.40), respiratory diseases (HR = 2.79, 95%CI = 1.32-5.87) and chronic obstructive pulmonary disease (COPD) (HR = 3.13, 95%CI = 1.07-9.17) as compared to never smokers. Former smokers who quit smoking for over 5 years were similar to never smokers on all-cause death, lung cancer, all-cause cancers, COPD, respiratory diseases and cardiovascular diseases. Conclusion Smoking plays a prominent role in increasing the mortality risk among the Taiwanese elderly. Disease mortality risks of elderly former smokers who quit smoking over 5 years were reduced to the same level as the never smokers.