Chest
Volume 95, Issue 3, March 1989, Pages 512-518
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Clinical Investigations
Subclinical Effects of Cigarette Smoking: A Five-Year Follow-Up of Physiologic Comparisons of Healthy Middle-aged Smokers and Nonsmokers

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Measurements of ventilatory function, lung elastic recoil, diffusing capacity, and distribution of ventilation were obtained on healthy middle-aged cigarette smokers and nonsmokers on two occasions five years apart in order to assess the effects of smoking and the change which may occur over this five-year interval. Subjects were drawn from a randomly selected sample of the population of Tucson, AZ. Exactly the same protocol, methods, and equipment were employed in both studies. Although very few of these healthy subjects had abnormal function, there were significant differences in most indices of function between smokers and nonsmokers. However, we could discern no difference between smokers and nonsmokers in change in function over five years. It appears that, in smokers who remain free of serious respiratory trouble, there are subtle changes which accumulate over the years and which are too gradual to detect over a five-year interval.

Section snippets

Methods

Candidates for this study were originally drawn from the randomly selected sample of the population of Tucson, AZ, enrolled in a prospective longitudinal study of respiratory health.2 Details of selection of subjects for this study have been described in detail.1 They were of middle age and denied a history of heart trouble, chest surgery, or physician-diagnosed asthma, chronic bronchitis or emphysema. At the time of the second evaluation, the subjects studied ranged in age from 53 to 65 years.

Results

Results were examined from two aspects. First, they were assessed for systematic significant and consistent differences between smokers and nonsmokers at the times of the two studies five years apart. Second, results were examined for changes over time and the changes evaluated for group differences.

Discussion

The objectives of this study were, first, to confirm the effect of cigarette smoking in healthy middle-aged subjects who had not developed overt airflow obstructive disease, and second, to assess any measurable differences in change in function in such smokers compared to nonsmokers after a five-year interval following the same study protocol. Subjects with physician-diagnosed respiratory disease were excluded when initially selected and those selected perceived themselves as healthy. Indeed,

Acknowledgment

The writers would like to express appreciation to Warren E. Collins, Inc for providing equipment used in a part of this study, to R. C. Schroter and R. K. Oxenham of the Imperial College of Science and Technology, London, for making available their exponential curve-fitting computer program, and to A. Reeves for assistance in manuscript preparation.

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  • Cited by (0)

    This study was supported by a Specialized Center of Research Grant HL14136 from the National Heart, Lung and Blood Institute and by a grant from the Flinn Foundation, Phoenix. Dr. Bloom is recipient of Pulmonary Academic Award HL00838 from the National Heart, Lung and Blood Institute

    Manuscript received June 20; revision accepted August 9

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