Abstract

Objectives An inception cohort of trades' apprentices had rapid declines in lung function (forced expiratory volume in 1 s (FEV₁)) and rapid increases in bronchial responsiveness (↑BR) over the first 2 years of employment. We used physician visit data to assess respiratory health over the following 13 years.

Methods Construction painter, electrician, insulator and machinist apprentices beginning at a British Columbia trade school in 1988 were invited to participate and were followed up 2 years later. Subjects were linked to provincial medical databases to examine physician visits for asthma and other respiratory illnesses for the 13 years following. Multivariable models with rapid decline in FEV₁ and rapid increase in BR from years 1 to 3 were constructed. Respiratory symptoms were also examined as predictors of visit rates and meeting a case definition (for asthma or other respiratory illness).

Results The cohort included 281 apprentices (97% are men). Sixteen subjects met the asthma case definition (≥2 visits coded as asthma in 1 year) and 20 met the other respiratory illness case definition (≥3 visits for bronchitis, emphysema, respiratory symptoms in 1 year). In models controlling for demographic factors and smoking, subjects with bronchitis symptoms at baseline were more likely to develop other respiratory illness during follow-up (RR 4.4, 95% CI 1.6 to 11.9). Apprentices who developed asthma symptoms over the first 2 years were approximately six times more likely to become asthma cases (95% CI 1.9 to 18.8). Those with a rapid increase in BR were at increased risk of becoming asthma cases (RR 5.5, 95% CI 1.9 to 16.1), as well as having higher asthma visit rates (RR 6.5). Subjects with rapid decline in FEV₁ were 3.2 times more likely to become asthma cases (95% CI 0.8 to 12.1).

Conclusions Changes in respiratory health early in adulthood, especially increased BR, are associated with respiratory physician visits. These findings are important for workplace screening and prevention and also suggest that physician visit databases are promising research tools in respiratory epidemiology.