title: Longitudinal analysis of the effects of smoking onset and cessation on pulmonary function.
abstract: We examined the effects of smoking onset and cessation on FEV1 in participants in the Tucson Epidemiological Study of Airways Obstructive Disease 18 yr of age or older who reported a change in smoking habits during 17 yr of follow-up. Subjects were classified as "new quitters" (n = 288) and "new starters" (n = 45) at each survey on the basis of questionnaire responses concerning current smoking habits. The pulmonary function data were analyzed using a mixed longitudinal or random effects model (REM). We compared FEV1 before and after changing smoking habits in the same subjects while adjusting for important covariables such as height, pack-years, and respiratory symptoms and diseases. The results for smoking cessation showed a beneficial effect related to quitting that was largest for younger subjects and decreased linearly with age. For women, quitting resulted in an improvement in FEV1 of 4.3% at 20 yr of age which decreased to 2.5% by 80 yr of age. Men had an improvement of only 1.2% at 20 yr of age and no improvement at 80 yr of age. After excluding subjects with low initial function (FEV1/FVC in the lowest quartile) and those with only a single observation after quitting, men (n = 70) showed a significantly higher FEV1 improvement of 4% at 20 yr of age that decreased linearly to zero by age 80 yr. In contrast, women in this subgroup (n = 89) had nearly the same degree of improvement at all ages. The onset results showed mean FEV1 values after starting smoking that were higher at the younger ages (< 23 yr) and that decreased more rapidly with age, compared with nonsmoking mean estimates, in both sexes.
authors.affiliation: Respiratory Sciences Center, University of Arizona, College of Medicine, Tucson 85724.
authors.forename: D L
authors.initials: DL
authors.lastname: Sherrill
authors.forename: C J
authors.initials: CJ
authors.lastname: Holberg
authors.forename: P L
authors.initials: PL
authors.lastname: Enright
authors.forename: M D
authors.initials: MD
authors.lastname: Lebowitz
authors.forename: B
authors.initials: B
authors.lastname: Burrows
mesh_terms: D000328:Adult; D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D001130:Arizona / Q000453:epidemiology; D005260:Female; D005500:Follow-Up Studies; D005541:Forced Expiratory Volume; D006801:Humans; D016018:Least-Squares Analysis; D016014:Linear Models; D008137:Longitudinal Studies; D008173:Lung Diseases, Obstructive / Q000145:classification / Q000175:diagnosis* / Q000453:epidemiology / Q000209:etiology* / Q000503:physiopathology; D008297:Male; D008875:Middle Aged; D012737:Sex Factors; D012907:Smoking / Q000009:adverse effects*; D016540:Smoking Cessation