Benefits of quitting smoking for chronic obstructive pulmonary disease and other tobacco related mortality in a 35-years cohort in China

He, Yao

Benefits of quitting smoking for chronic obstructive pulmonary disease and other tobacco related mortality in a 35-years cohort in China

Sunday, 17 August 2014

Exhibit hall (Dena'ina Center)

Yao He, PhD , Chinese People's Liberation Army General Hospital, Beijing, China

Bin Jiang , Chinese People's Liberation Army General Hospital, Beijing, China

Liang Shou Li , 4th Military Medical University, Xi'an, China, Xi'an, China

Lan Sun Li , 4th Military Medical University, Xi'an, China, Xi'an, China

Dong Ling Sun , Chinese People's Liberation Army General Hospital, Beijing, China, Beijing, China

Lei Wu , Chinese People's Liberation Army General Hospital, Beijing, China

Miao Liu , Chinese People's Liberation Army General Hospital, Beijing, China

Shu Fang He , Kun Lun Machinery Factory Hospital, Xi'an, China, Xi'an, China

Bao Qing Liang , Kun Lun Machinery Factory Hospital, Xi'an, China, Xi'an, China

Frank B. Hu , Harvard School of Public Health, Boston Massachusetts, Boston, MA

Tai Hing Lam, MD , The University of Hong Kong, Hong Kong, Hong Kong

INTRODUCTION:

Prospective evidence on the association of smoking cessation and tobacco related mortality, especially chronic obstructive pulmonary disease (COPD) in Asia is scarce. Previous studies, mostly based on baseline only, are subject to ill-quitter bias and misclassification from changes in smoking during follow-up.

METHODS:

We followed up a cohort for 18 years (1976-1994) to assess change in smoking and then for 17 years (1994-2011) to examine the relationship between continuing smoking, new quitting and mortality in 1494 Chinese (961 men, 533 women) in Xi’an, China.

RESULTS:

In 1976-1994, 38.7% (38.3 % in men and 41.9% in women) of current smokers had quit, and from 1994 to 2011, 488 (359 men and 129 women) had died. Ever smokers(new quitters plus continuing current smokers) in 1976 had increased risks of lung cancer, coronary heart disease (CHD), thrombotic stroke, COPD, and all tobacco-related mortality, with significant dose-response relationships (P for trend: 0.010 to <0.001). During 1976-1994, new quitters (during follow-up) showed reduced risk for most diseases. Compared with continuing current smokers, relative risk (RR) (95% CI) for all tobacco-related mortality was 0.68(0.46-0.99) for those who quit for 2-7 years and 0.56(0.37-0.85) for at least 8 years. The corresponding RRs were 0.69 and 0.45 for lung cancer, 0.78 and 0.51 for CHD, 0.76 and 0.84 for thrombotic stroke, 0.89 and 0.61 for COPD.

CONCLUSIONS:

Smoking increased and quitting at middle age (at about 50) substantially reduced tobacco-related and particularly COPD mortality in China. The benefits of smoking cessation in previous cohort studies based on baseline smoking status only should be underestimated.