Factors affecting inappropriate use of combination therapy for asthma: analysis of two child cohorts

Abstract

Aim: The majority of Australian children aged 3-8 years with asthma who are prescribed inhaled steroids (ICS) receive this medication in combination with long-acting beta agonists. We investigated predictors of use of combination therapy, as opposed to ICS alone, in this population. Methods: Two cohorts of children, aged 0-1 and 4-5 years at recruitment, were assessed for parent-reported asthma three times over a 4-year period. For children who reported asthma at any of the assessments, dispensing of medications for asthma in the year prior to the last assessment (at 3-4 and 7-8 years) was ascertained from linked Pharmaceutical Benefits Scheme data. In children with asthma who were taking any ICS we examined the predictors of use of combination therapy as opposed to ICS alone using logistic regression that accounted for the survey design. Results: Among children with asthma reported at or before age 3-4 years, 7.0% (95%CI 5.7-8.3) were dispensed the combination therapy and 5.5% (95%CI 4.2-6.9) were dispensed ICS alone. Among children with asthma aged 7-8 years, these proportions were 12.8% (95% CI 10.8 -14.7%) and 4.1% (95%CI 2.9-5.4), respectively. Factors associated with dispensing of combination therapy, as opposed to ICS alone, in the older cohort were having an older sibling (OR=1.7, 95%CI 1.2-2.6), having eczema (OR=1.5, 95%CI 1-2.3) and having parent-reported food or other allergies (OR=2.0, 95%CI 1.4-3.0). In the younger cohort, being born prematurely (OR=2.6 (95%CI 1.2-5.9) was associated with a greater likelihood of being dispensed combined therapy. Conclusions: Among 7-8 year olds with asthma who need ICS for asthma those who are atopic are more likely to than non-atopic children to be dispensed combination therapy than ICS alone. There is a paucity of clinical trial evidence to support this practice. Supported by: Asthma Foundation NSW (Ross Trust)