[Determinants of geographic variations in asthma medication in Quebec]

The study of geographic variations in the use of medication can constitute an interesting and useful option in public health surveillance for the identification of population needs and for the fair partition of resources. Many studies report variations in the use of medication that are not always understood. Considering the importance of medication, particularly for chronic diseases like asthma, it is important to identify factors that can explain geographic differences in the utilization of medications in order to determine optimal prescription practices.

We used a multilevel analysis to explore determinants of variation among welfare recipients and subscribers covered by the Quebec public drug plan, aged five to 44, who claimed at least one prescription for an asthmatic medication in 2003. The analysis was based on 73 small areas in Quebec's 15 health regions.

Prevalence of usage and hospitalization rates are the main predictors of variation in medication intensity. On the other hand, prevalence of usage is related to the area of residence, proportion of welfare recipients and prevalence of smokers. The quality of medication is related to practitioners' specialty.

Different factors contribute to the understanding of geographic variations in asthma medication but it remains important to control for severity. Small area analysis makes it possible to identify specific areas facing more important problems in the prevalence and use of medication for asthma and thus leads to better understanding of local needs for more targeted interventions.