Occupational exposure and incidence of asthma based on prescription of drugs.

Prescription of medication for obstructive lung diseases (ATC code R03) has previously been shown to be an indicator of actual asthma. In this study we have combined information from a cohort study with data from redeemed prescriptions between 2000 and 2013 extracted from the National Danish Prescription register. In 2003 a total of 7,255 persons aged between 20 and 44 filled in a questionnaire including their longest held job. The jobs of 6,470 subwere coded according to ISCO-88 and an asthma JEM was applied. Prevalent asthma was defined as two prescription of a R03 drug within 2 years. Incident asthma between 2003 and 2013 was defined by not having a receipt in the previous years. Data was analyzed separately for each sex using logistic regression and presented as odds ratios with 95% confidence intervals. Among those having a job were identified 331 (5.1 %) incident cases and 467 (7.2%) prevalent cases. In females increased incidence were seen in exposures to reactive LMW substances (OR1.52 (1.08-2.14)), cleaning agents (OR 1.56 (1.08-2.24)), metals (OR 3.29 (1.63-6.64)) and exhaust (OR 3.44 (0.96-12.2)), while increased prevalence was seen with mite exposure (OR 4.45 (1.75-11.3)) and irritant gases (OR 1.76 (1.15-2.69)). In males no increased incidences were seen and only an increased prevalence with mixed environments (OR 2.22 (1.12-4.41)). Using administrative register data to identify cases of asthma in young adults can reveal meaningful associations with well-known asthmagenic exposures, especially in females. Implementing the analyses on register data from larger populations will have high power and can possibly detect increased risks due to rare exposures or change in risk over time.