Asthma drug ratios and exacerbations: claims data from universal health coverage systems

In claims data, controller-to-total asthma drug ratios may reflect adequacy of disease management. We verified whether asthma patients with high ratios (>= 50%) experienced fewer asthma-related outcomes. Two ratios were studied: that of the inhaled corticosteroids to total asthma drug (ICS/R03) and that of the inhaled corticosteroids plus leukotriene antagonist receptors-to-total asthma drug (ICS+LTRA/R03). Patients aged 13-40 years, with >= 3 respiratory drugs dispensed prescriptions in 2005 were selected from the French national claims data. After excluding null ratios, two groups were defined according to ratio values in 2007: low-ratio group (0%< ratio < 50%) and high-ratio group (ratio >= 50%). For both ratios, asthma-related outcomes and medical-resource utilisation were compared between groups. Of 2162 patients (mean age 27 years and 52% female), patients with non-null ratios were 81% and 85% for ICS/R03 and ICS+LTRA/R03 ratios, respectively. Patients with high ratios were less likely to receive oral corticosteroids than those in the low-ratio group (relative risk 0.79, 95% CI 0.72-0.88, and 0.80, 95% CI 0.72-0.88, for ICS/R03 and ICS+LTRA/R03, respectively). High ratio groups also presented fewer asthmarelated hospitalisations. Significant negative correlations were also observed for both ratios, when studied quantitatively, according to patients' dispensed level of oral corticosteroids in 2007. In claims data, both ICS/R03 and ICS+LTRA/R03 >= 50% were related to fewer asthma-related outcomes. Ratios should be explored to identify asthma patients at risk of exacerbations. Low ratios can be considered as risk factors of exacerbation whatever the underlying cause.