Participants were classified as current smokers, former smokers, and never-smokers of cigarettes. Subjects were also classified by the number of pack-years of smoking (ie, 0, 0.1 to 9.9, 10.0 to 19.9, and > 20.0 pack-years). Body mass index (BMI) was calculated as weight (in kilograms) divided by height (in meters) squared. Average alcohol consumption was categorized by the number of drinks per week (ie, 0, 1 to 7, 8 to 21, and > 22 drinks per week). Here, one drink is equivalent to the intake of 12.5 g ethyl alcohol.
The data were summarized as the mean (SD) for continuous variables, and as a percentage for categoric variables. The comparison of means between genders within the same age groups was made using a two-sample t test. The comparison of proportions was based on the use of logistic regression models. Logistic regression models also were used to assess the independent relationship between airway obstruction and sociodemographic and health-related factors. further
The mean age of the study participants was 45.8 years (range, 18 to 82 years). Demographic details of the subjects are shown in Table 1. The proportions of men who were current and former smokers were 50.7% and 22.4%, respectively. For women, the corresponding proportions were 3.8% and 0.3%, respectively. The mean age of the 540 individuals who did not receive pulmonary testing (45.5 years; range, 18 to 89 years) was not significantly different from the mean age of those who completed the tests. Among those excluded, however, there were more men (64.8%) than women (35.2%). The proportion of current and former smokers without pulmonary testing (36.5% and 14.2%, respectively) was also higher than in those in whom pulmonary data were available.
The prevalence of airway obstruction was 10.3% (men, 17.0%; women, 5.6%) by the 1986 ATS criteria (Table 2).
Table 1—Baseline Information by Gender and Age
|18-44 yr (n = 232)||a 45 yr (n = 251)||18-44 yr (n = 394)||a 45 yr (n = 283)|
|Age, yr||36.2 ± 6.7||58.3 ± 9.5||36.2 ± 5.5||57.7 ± 9.7|
|Smoking habits, % Current smokers||58.2t||43.8||5.3||1.8|
|FEVb % predicted||100.5 ± 12.6||99.1 ± 18.0||103.9 ± 12.5||108.3 ±17.3|
|FEV/FVC, %||83.8 ± 6.0j||78.0 ± 8.2||86.4 ± 5.5||82.2 ± 6.5j|
|FEV/VC, % predicted||104.6 ± 8.8||105.0 ± 12.2||106.5 ± 9.6||107.2 ± 11.8|
Table 2—Prevalence of Airway Obstruction by Gender and Age
|Variables||18-44 yr (n = 232)||ia 45 yr (n = 251)||18-44 yr (n = 394)||a 45 yr (n = 283)|