@article {8402, title = {Lung function decline in former smokers and low-intensity current smokers: a secondary data analysis of the NHLBI Pooled Cohorts Study.}, journal = {Lancet Respir Med}, volume = {8}, year = {2020}, month = {2020 01}, pages = {34-44}, abstract = {

BACKGROUND: Former smokers now outnumber current smokers in many developed countries, and current smokers are smoking fewer cigarettes per day. Some data suggest that lung function decline normalises with smoking cessation; however, mechanistic studies suggest that lung function decline could continue. We hypothesised that former smokers and low-intensity current smokers have accelerated lung function decline compared with never-smokers, including among those without prevalent lung disease.

METHODS: We used data on six US population-based cohorts included in the NHLBI Pooled Cohort Study. We restricted the sample to participants with valid spirometry at two or more exams. Two cohorts recruited younger adults (>=17 years), two recruited middle-aged and older adults (>=45 years), and two recruited only elderly adults (>=65 years) with examinations done between 1983 and 2014. FEV decline in sustained former smokers and current smokers was compared to that of never-smokers by use of mixed models adjusted for sociodemographic and anthropometric factors. Differential FEV decline was also evaluated according to duration of smoking cessation and cumulative (number of pack-years) and current (number of cigarettes per day) cigarette consumption.

FINDINGS: 25 352 participants (ages 17-93 years) completed 70 228 valid spirometry exams. Over a median follow-up of 7 years (IQR 3-20), FEV decline at the median age (57 years) was 31{\textperiodcentered}01 mL per year (95\% CI 30{\textperiodcentered}66-31{\textperiodcentered}37) in sustained never-smokers, 34{\textperiodcentered}97 mL per year (34{\textperiodcentered}36-35{\textperiodcentered}57) in former smokers, and 39{\textperiodcentered}92 mL per year (38{\textperiodcentered}92-40{\textperiodcentered}92) in current smokers. With adjustment, former smokers showed an accelerated FEV decline of 1{\textperiodcentered}82 mL per year (95\% CI 1{\textperiodcentered}24-2{\textperiodcentered}40) compared to never-smokers, which was approximately 20\% of the effect estimate for current smokers (9{\textperiodcentered}21 mL per year; 95\% CI 8{\textperiodcentered}35-10{\textperiodcentered}08). Compared to never-smokers, accelerated FEV decline was observed in former smokers for decades after smoking cessation and in current smokers with low cumulative cigarette consumption (<10 pack-years). With respect to current cigarette consumption, the effect estimate for FEV decline in current smokers consuming less than five cigarettes per day (7{\textperiodcentered}65 mL per year; 95\% CI 6{\textperiodcentered}21-9{\textperiodcentered}09) was 68\% of that in current smokers consuming 30 or more cigarettes per day (11{\textperiodcentered}24 mL per year; 9{\textperiodcentered}86-12{\textperiodcentered}62), and around five times greater than in former smokers (1{\textperiodcentered}57 mL per year; 1{\textperiodcentered}00-2{\textperiodcentered}14). Among participants without prevalent lung disease, associations were attenuated but were consistent with the main results.

INTERPRETATION: Former smokers and low-intensity current smokers have accelerated lung function decline compared with never-smokers. These results suggest that all levels of smoking exposure are likely to be associated with lasting and progressive lung damage.

FUNDING: National Institutes of Health, National Heart Lung and Blood Institute, and US Environmental Protection Agency.

}, keywords = {Adult, Aged, Case-Control Studies, Ex-Smokers, Female, Follow-Up Studies, Humans, Lung, Male, Middle Aged, National Heart, Lung, and Blood Institute (U.S.), Non-Smokers, Respiratory Physiological Phenomena, Smokers, Smoking, Spirometry, United States, Young Adult}, issn = {2213-2619}, doi = {10.1016/S2213-2600(19)30276-0}, author = {Oelsner, Elizabeth C and Balte, Pallavi P and Bhatt, Surya P and Cassano, Patricia A and Couper, David and Folsom, Aaron R and Freedman, Neal D and Jacobs, David R and Kalhan, Ravi and Mathew, Amanda R and Kronmal, Richard A and Loehr, Laura R and London, Stephanie J and Newman, Anne B and O{\textquoteright}Connor, George T and Schwartz, Joseph E and Smith, Lewis J and White, Wendy B and Yende, Sachin} }