Risk Factors for Non-Adherence to Inhaled Corticosteroids in Preschool Children with Asthma

Non-adherence to asthma controllers increases morbidity among school-aged children. This study aimed to determine non-adherence risk factors in preschool children with asthma. We investigated 172 children <6 years diagnosed with asthma in 2018 and analyzed baseline characteristics and loss of control events extracted from the medical records for four years following diagnosis. At end of follow-up, 79 children had a prescription of inhaled corticosteroids (ICS) and were included in the analyses. Adherence was assessed in a two-year period through pharmacy claims using percentage of days covered (PDC) analyzed dichotomously with non-adherence defined as PDC < 80% and using adherence ratio (AR) defined as days with medical supply divided by days without. Of the 79 children, 59 (74.7%) were classified as non-adherent. In analyses adjusted for sex, age and exacerbations prior to inclusion, adherence was positively associated with having had a loss of control event requiring a step-up in asthma controller ((a)AR:2.34 [1.10;4.98], p = 0.03), oral corticosteroids ((a)AR:2.45 [1.13;5.34], p = 0.026) or redeeming a short-acting b2-agonist prescription ((a)AR:2.91 [1.26;6.74], p = 0.015). Further, atopic comorbidity was associated with increased adherence ((a)AR:1.18 [1.01;1.37], p = 0.039), whereas having a first degree relative with asthma was associated with worse adherence ((a)AR:0.44 [0.23;0.84], p = 0.015). This study found poor adherence to ICS among three quarters of preschool children with asthma. Increasing adherence was associated with atopic comorbidity and loss of control events, whereas lower adherence was associated with atopic predisposition. These findings should be considered to improve adherence in preschool children with asthma.