Real-World Medication Adherence and Medication Reviews in Adults and Children With Cystic Fibrosis.

BACKGROUND: People with cystic fibrosis (pwCF) have complex treatment regimens with cystic fibrosis transmembrane conductance regulator (CFTR) modulators and supportive therapies. Evidence on adherence across cystic fibrosis (CF) therapies using different assessment methods and the added value of medication reviews remains limited. OBJECTIVE(S): This study compared adherence across CF therapies using three assessment methods and evaluated the contribution of medication reviews. METHODS: This cross-sectional study (February to April 2025) included pediatric and adult pwCF at Maastricht University Medical Centre+. Adherence to CFTR modulators and supportive therapies (vitamin supplements, pancreatic enzymes, inhalers, and nebulizers) was assessed with pharmacy refill data (medication possession ratio, MPR); self-reported adherence (Medication Adherence Report Scale-5, MARS-5), and structured medication reviews. The primary outcome was the proportion of pwCF adherent to CF medication per assessment method. Secondary outcomes were the within-patient differences in adherence between CFTR and supportive therapies (McNemar's exact test) based on MPR and the number and acceptance of DRP-interventions in the medication review. RESULTS: Forty-three pwCF (17 children, 26 adults; 39.5% female) were included. For CFTR modulators, adherence was 91.7% (MPR), 91.2% (MARS-5), and 72.2% (medication review). For supportive therapies, adherence was 56.3%, 77.7%, and 77.4%, respectively. Four nonadherent pwCF were identified exclusively through medication review. Within-patients, adherence was higher for CFTR modulators than for supportive therapies (p < 0.001). Medication reviews identified 51 DRPs in 41 pwCF (including nonadherence in 12 pwCF), all proposed interventions were accepted by the treating physician. CONCLUSION: Adherence varied by medication class and assessment method. Medication reviews provided clinically relevant information in addition to refill-based and self-reported measures.