Compared to inhaled corticosteroids (ICS), better use of leukotriene-receptor antagonists (LTRA) may lead to a greater reduction in exacerbations among asthmatic children in real-life settings.
To test this hypothesis, we used the Quebec administrative databases and identified a cohort of 27,355 asthmatic children aged 5-15 years in whom ICS or LTRA monotherapy was initiated in 1998-2005. The primary outcome was the rate of moderate-or-severe asthma exacerbations (emergency department visit or hospitalization for asthma or a dispensed prescription of oral corticosteroids) over the subsequent year. The adjusted rate ratios (RR) of asthma exacerbations were estimated with Poisson regression models. To minimize confounding by indication, all analyses were stratified by the presence or not of an asthma exacerbation in the year before treatment initiation. We also measured the proportion of days with supply prescribed and patient's adherence with the Proportion of Prescribed Days Covered (PPDC).
The risk of exacerbations was significantly higher in the ICS than the LTRA group among children with no previous exacerbation (RR = 2.3; 95% CI:1.3-4.0), but not in those with =1 exacerbations (RR = 1.6; 0.8-3.1). The PPDC was similar between the groups (66%) but the proportion of days with supply prescribed was significantly higher in the LTRA than the ICS group (52% vs. 34%), resulting in higher use.
While confounding by indication cannot be firmly ruled out, ICS appears to be more frequently prescribed as an intermittent than a daily controller therapy resulting in less use, which may contribute to the apparent lower effectiveness compared to LTRA.