International trends in admissions and drug sales for asthma

To test whether national patterns of asthma drug use, particularly inhaled corticosteroids (ICS), are related to the rate of acute severe asthma exacerbations.

The relation of international trends in hospital admissions for asthma with asthma drug sales was examined using country-specific regressions over the period 1990-1999. Pooled estimates of the regression coefficients were calculated using random effects models.

Data on asthma admissions and asthma drug sales (including the sub-category ICS) were obtained from 11 countries. There was a negative relationship between falling admissions and rising sales of respiratory drugs and ICS in 9 of these 11 countries. A pooled estimate of the change in asthma admission rate per 10,000 associated with a unit increase in sales rate was -6.3 (95% CI -10.4 - -2.3) for all asthma drugs and -11.2 (95% CI -19.7 - -2.8) for ICS.

At the national level, there is good evidence that over the last decade, increased sales of asthma drugs, and ICS in particular, were associated with a decline in rates of hospital admission for asthma. This is consistent with a beneficial effect of increasing use of asthma drugs, but other explanations such as decreasing prevalence could also be responsible.