Baseline characteristics of the cohorts
In both cohorts the response rate was higher among women both at baseline and at the follow-ups (Table 1). The mean age of the individuals was 44.6 years in the cohort recruited in 1996 and 47.7 years in the cohort recruited in 2006. Smoking was more common in 1996 than 2006 (27.4% vs. 19.3%). Women reported significantly higher prevalence of attacks of SOB, allergic rhino-conjunctivitis and use of asthma medication than men in both cohorts (Table 2).