Background/Objectives: Asthma is the most prevalent non-communicable disease in childhood and adolescence and continues to represent a major global health concern. Beliefs about medication and illness perceptions are recognized as dynamic psychosocial determinants of asthma outcomes, yet evidence in pediatric populations remains scarce. This study aimed to evaluate the longitudinal relationships that beliefs about medicines and illness perceptions present with adherence to inhaled corticosteroids, asthma symptom control, and exacerbations in children and adolescents with asthma.

Methods: Participants from the ARCA (Asthma Research in Children and Adolescents) cohort -a prospective, multicenter, observational study (NCT04480242)- were followed via computer-assisted telephone interviews every 6 months and after each exacerbation, and via the ARCA smartphone app monthly. The following questionnaires were administered: Beliefs about Medicines Questionnaire, Illness Perceptions Questionnaire revised, Medication Intake Survey-Adherence, and Asthma Control Questionnaire. Multilevel mixed-effects linear and logistic regression models accounting for correlation among repeated measures were constructed, adjusting by age and sex.

Results: A total of 165 participants aged 6-14 years at the recruitment, with a mean follow-up period of 5.7 years, contributed 1,328 interviews. Beliefs of a lower need of medication and higher concerns about medicines were consistently associated with poorer adherence to inhaled corticosteroids (β = -6.9, p < 0.05 and β = -7.7, p < 0.05, respectively). Illness perceptions were related to better symptom control (β = -0.33, p < 0.001) and lower exacerbation risk (OR = 0.29, p < 0.001).

Conclusions/Recommendations: Beliefs about medicines and illness perceptions exhibit distinct and complementary roles. Beliefs about medicines primarily influence medication adherence, whereas illness perceptions are related to asthma control and exacerbations. Integrating beliefs about medicines into routine care may enhance personalized strategies aligned with quality use of medications.

Funding: ISCIII PI15/00449, AGAUR2021 SGR 00624.