Background: Considerable variation exists in the use of antiasthmatic drugs in different counties in Sweden. The reasons for this variation are unknown. A study was performed to determine if there is an association between sales of antiasthmatic drugs and the prevalence of obstructive airway diseases in two adjoining Swedish counties.
Method: The prevalence of asthma-associated symptoms in the county of Jämtland where there is high drug use, and the county of Gävleborg where it is lower, was assessed in 1990 by a postal questionnaire answered by 11,300 subjects. Three age groups were included: all 16 year olds, 13% of those aged 30-39 years, and 13% of 60-69 year olds. A total of 2100 subjects reporting airway symptoms in a questionnaire and 450 asymptomatic controls were further investigated at an interview with lung function tests and, in 500 cases, with a methacholine challenge. Asthma was diagnosed in subjects reporting a typical history or repeated episodes of dyspnoea and wheezing, or dry cough combined with reversibility in FEV1, variability in peak expiratory flow, or a PC20 value of < or = 4 mg/ml.
Results: The prevalence of current asthma was close to 8% in all age groups in Jämtland and significantly lower (close to 6%) in all age groups in the warmer, more industrialised and more densely populated county of Gävleborg. A gender difference with a higher prevalence in women was found in Gävleborg but not in Jämtland. There was no significant difference in the use of inhaled beta 2 stimulants among subjects with asthma in the two counties. Inhaled steroids were used more often in Jämtland. However, they were used regularly by fewer than 10% of asthmatic subjects in the two younger age groups.
Conclusion: The differences in the use of antiasthmatic drugs in these two counties reflect a difference in the prevalence of obstructive airway disease.