A comparison of childhood asthma case definitions based on parent-reported data.

Abstract Purpose To compare research definitions of childhood asthma based on parent-reported data. Methods We conducted a multicenter, prospective cohort study of 921 infants hospitalized for bronchiolitis. Follow-up was conducted via biannual parent interviews. Asthma definitions were developed using parent-reported data: clinician diagnosis by age 5 years (“broad definition”); clinician diagnosis by age 5 years with either asthma medication use or asthma symptoms during age 4-4.9 years (“epidemiologic definition”); clinician diagnosis by age 5 years with either long-term inhaled corticosteroid use or asthma symptoms during age 4-4.9 years (“strict definition”); and a “flexible definition” met by any 2 of the 3 criteria in the epidemiologic definition. Asthma outcome definitions were evaluated using unadjusted associations with known major asthma risk factors, and validated against the medical record in a subset (n=116). Results Asthma prevalence for the broad definition was 294/875 (34%); epidemiologic definition, 235/859 (27%); strict definition, 229/859 (27%); and flexible definition, 364/826 (44%). Risk factors had similarly strong associations with definitions that required clinician diagnosis, and weaker associations with the flexible definition. The epidemiologic and strict definitions had the highest specificity (96%) and PPV (92%). Conclusions Parent report of clinician-diagnosed asthma correlates well with known asthma risk factors.