Smoking and respiratory health among first year college students in Navarra

Active smoking has been identify as a major risk factor for accelerated decline of respiratory function, development of chronic obstructive pulmonary disease (COPD, i.e. chronic bronchitis and emphysema) and causally related to lung cancer.

In adolescents, smoking increases in the number and severity of respiratory illness, decreased physical fitness, adverse changes in blood cholesterol levels, more school absenteeism, and appears to reduce the rate of lung growth and the maximum lung function that can be achieved compared with non-smokers.

Although the effects take some time to develop and are not immediately apparent after beginning the smoking habit. Studies show that, some measurable smoking related changes in respiratory function can be detected as early as 1 to 2 years after smoking is started. The rise in the prevalence of smoking in adolescents in recent years has implications for future adult smoking rates and health costs. Therefore understanding the impact of smoking at young age may help public health policy makers to develop strategy to prevent or delay adolescent smoking.

The present study was carried out to determine the effect of short-term smoking habits on respiratory health in young college students.

The study population consisted of 1170 first year Navarra college students between 18 and 19 years of age with a mean age of 19 (range 18 to 35 years) Ten subjects were excluded from this analysis due to missing data for gender. This resulted in a total sample of 1160. Male (N = 416,35.9%) Female (N = 744, 64.1%). Subjects were categorized either as daily-smokers, occasional-smokers, and non-smokers based on self-reported smoking status. Of the 1160 samples, 44 had missing smoking data. Smoking status was validated using biological markers such as serum cotinine and breath carbon monoxide (CO). Breath CO was performed using Bedfont EC-50 smokerlyzer model (Bedfont instruments, Kent, UK). Serum samples were obtained after centrifugation and they were shipped in dry ice and sent by special courier to Bielefeld School of Public Health Laboratory, Germany, where serum cotinine was measured by radioimmunoassay. The effect of smoking on respiratory health was assessed by pulmonary function test (PFT) after adjusted for age, height gender and weight. Pulmonary function test was performed using calibrated pneumotachograph spirometer (Datorspyr 100, Sybel 5121 Barcelona) in accordance with the American Thoracic Society (1987) European Respiratory Society (1993) and the Spanish Society of Respiratory Disease and Thoracic Surgery (1985) standards. Casan (1985) reference values for pulmonary function test for this population were used.

Statistical analyses were performed using SPSS program version 10.0 (SPSS Inc. Chicago, Illinois, USA). One-way analysis of variance (ANOVA) was used to compared the means of the nine different spirometric indices for smoking and non-smoking groups with both Scheffé and Tukey post-hoc tests for comparisons. Multiple regression analysis was performed to assess the relation between cigarette smoking and spirometric parameters.

The results were considered statistically significant if the p value was less than 0.05.

Of the 1116 respondents, 32,7% (N=365) were daily-smokers, 17,7% (N= 198) occasional-smokers, and 49,6% (N= 553) non-smokers. The overall smoking prevalence was 50, 4%. Because no significant difference was found between occasional-smokers and non-smokers in the regression analysis for the pulmonary function tests, for this reason, smokers were considered as a single group. The mean pulmonary function values (expressed as volume of air in liters or L/s) of all the pulmonary function tests (FVC, FEV1, FEV.05, FEV1/FVC%, FEF25-75%, MEF25%, MEF50%, MEF 75%,) were significantly lower in smokers as compared to non-smokers (p<0.05). Except for FVC which no significant differences in the group means were observed. The following results were obtained for the pulmonary function tests between smokers and non-smokers after exclusion of occasional-smokers. FVC (3.80 vs. 3.89), FEV1 (3.14 vs. 3.33), FEV.05 (2.30 vs.2.48), FEV1/FVC% (85.97 vs. 88.25), FEF25-75% (3.65 vs. 4.07), MEF25% (2.19 vs. 2.44), MEF50% (4.16 vs. 4.66), MEF 75% (5..56 vs.6.25).

Based on the results of this study, it is concluded that, cigarette smoking is associated with a decrease in respiratory function and appeared to start at an earlier age in smokers. Although the duration and intensity of smoking in this age group, may have a weak impact to cause respiratory health abnormalities often observed among older smokers. The results emphasize the need for effective measures to prevent adolescent smoking