[Influence of smoking habit on respiratory function in young asthmatics: follow-up study from 16-30 years of age].

Introduction: Smoking habit of 54 asthmatics was followed for 15 years.

Objective: To examine if there was any difference of lung function tests between smoking and nonsmoking young asthmatics.

Method: Based on questionnaires, clinical examinations, lung function tests and skin prick tests, 54 adolescents with asthma were separated out of 1134 pupils of one Belgrade high school. They were followed-up till the age of 30.

Results: 62.9% of subjects were females and 37.1% were males. Average age at the beginning was 16.3 and 29.6 at the end of study. In 13.0% of subjects, the asthma manifested in the first year of life, in 72.2% between 2-6 years of age and in 14.8% of our subjects, the asthma developed after 7th year. The symptoms of asthma in last 12 months were present in 54.8% of our subjects at the age of 16, compared to 77.8% of asthmatics with asthma symptoms at the age of 30. Percent of smokers increased cumulatively from 16.7% at the beginning of study up to 57.5% upon its completion. Number of cigarettes increased from 7.5% to 16.5% cig/day in a smoker from the adolescent period until the end of study, with no difference in relation to sex. Average duration of smoking experience was 11.5 years, no difference in relation to gender. Values of VC, FVC, FEV1, PEF and MEF75 were always lower in asthmatics-smokers, but with no statistical difference. Tiffeneau index, MEF25 and MEF50 were statistically lower in the smoking group at the age of 30 compared to their values at the age of 21.

Conclusion: Smoking does affect lung function of asthmatics that started to smoke and Tiffeneu index, MEF25 and MEF50 were statistically lower as early as at the age of 30.