High physician adherence to phenotype-specific asthma guidelines, but large variability in phenotype assessment in children.

Background: The implementation of international pediatric asthma guidelines hinges on the distinction between intermittent and persistent phenotypes and the prescription of recommended phenotype-specific pharmacotherapy.

Objectives: To ascertain key factors associated with specialist-confirmed phenotype and document physicians' adherence to practice recommendations in an academic pediatric asthma center.

Design/methods: Using electronic health records, we identified a cohort of children aged 1-17 years who presented to a tertiary-care asthma center between 2002 and 2007 and received a diagnosis of asthma from a pediatric specialist. Outcomes included: determinants of phenotypes and conformity with phenotype-specific treatment recommendations.

Results: Of the 3490 eligible children (11,119 visits), most (47%) were preschoolers, 35% were 6-11 years and 18%, 13-17 years. Of children with confirmed asthma, 59% were classified on presentation as having intermittent, 41% as persistent, asthma. The within-patient phenotype varied over time with a consistency index of 0.76 (best=1); the latter was significantly lower in preschoolers than older children (p<0.0001). The persistent phenotype was highly physician-dependent; it was also positively associated with child's age, asthma severity, multiple triggers, calendar year, and duration of follow-up. Compared to 33% of children with intermittent asthma, 82% of those with persistent asthma were prescribed a maintenance controller, most as monotherapy; combination therapy was usually prescribed after a trial of monotherapy.

Conclusion: Pediatric asthma specialists were highly adherent to phenotype-specific pharmacotherapy. However, even in an academic center, the notable degree of intra-patient and between-physician variation in phenotype, particularly in preschoolers, was an important impediment to prescribing a maintenance controller. The findings underline the importance of developing validated and standardized means of assessing phenotypes, applicable to the whole pediatric age spectrum.