Differences in utilisation of asthma drugs between two neighbouring Swedish provinces: relation to prevalence of obstructive airway disease.

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.