Pharmacotherapeutic Medication Adherence in Patients With Allergic Rhinitis: A Systematic Review and Meta-Analysis

Medication adherence is essential for effective management of allergic rhinitis (AR), yet real-world adherence to guideline-recommended pharmacotherapies remains poorly characterized. This systematic review and meta-analysis aims to estimate pooled adherence proportions to prescribed intranasal corticosteroids and oral antihistamines in adults with AR, further stratified by adherence measurement method and geographic region.

Twelve studies encompassing 191,103 AR patients were included. Overall pooled adherence to both intranasal corticosteroids and oral antihistamines was 43%, with substantial heterogeneity across studies. Adherence estimates differed significantly by measurement method with self-reported adherence consistently exceeding pharmacy refill-based estimates for both medication classes. Significant geographic variation was also observed, with intranasal corticosteroid adherence ranging from 17% in North America to 61% in Asia, and oral antihistamine adherence ranging from 26% in North America to 48% in Northern and Western Europe. Peters' test did not indicate any significant publication bias and a Leave-One-Out (LOO) sensitivity analysis showed that no single study had a disproportionate effect on the overall effect size. Adherence to pharmacotherapy in AR is suboptimal, highly method-dependent, and varies significantly across geographic regions. These findings suggest that reported adherence rates are not only influenced by patients' behaviour, but also by the methods used to measure adherence and the broader healthcare environment. Integrating methodological rigour with geographic stratification provides more informative benchmarks for clinical practice and highlights the need for context-sensitive strategies to improve real-world AR management. Future research should prioritize standardized adherence measurement and prospective studies in underrepresented regions.