Background: To determine medication adherence to intranasal corticosteroid spray (INCS) among allergic rhinitis (AR) patients with comorbid medical conditions. Methods: A cross-sectional study was conducted. Adults above 18 years old with persistent symptoms of AR and comorbid physician-diagnosed asthma, eczema, diabetes mellitus (DM) and hypertension (HPT) were included. The severity of symptoms was assessed by the total nasal symptom score (TNSS), medication adherence was based on the patients’ diaries and barriers to adherence were analyzed by the Brief Medication Questionnaire. Results: 185 participants were enrolled. The medication adherence was 58.9%. Medication adherence was significantly superior in participants with elevated total serum immunoglobulin E (IgE) (χ2 = 8.371, p < 0.05), house dust mite (HDM) allergy to Dermatophagoides pteronyssinus (DP) type (χ2 = 5.149, p < 0.05) and severe TNSS at the first visit (χ2 = 37.016, p < 0.05). Adherence was twice more likely in DP allergy, 2.7 times more likely in elevated total IgE and 15 times more likely in severe TNSS at the first visit. Among the barriers to adherence was lack of symptoms, taking medication only when necessary, fear of adverse effects, running out of medication, experiencing bothersome effects, ineffective response, forgetfulness and taking too many medications. Only lack of symptoms, taking medication when symptomatic, fear of adverse effects and running out of medication were significant. No significant association was found between asthma/eczema (χ2 = 0.418, p > 0.05), HPT/DM (χ2 = 0.759, p > 0.05) and multi-medicine use (χ2 = 1.027, p > 0.05) with medication adherence. Conclusions: Patients having AR with severe nasal symptoms at first presentation, who are sensitized to DP HDM and who have elevated total serum IgE levels have a higher adherence to INCS use. The use of multiple medicines had no impact on the adherence to INCS. As a lack of symptoms was a barrier towards adherence, the benefits of using INCS according to the prescribed dose and frequency must be emphasized to patients with mild and moderate AR at each medical visit. A good rapport between patients and their health care providers is needed to build trust and overcome the barriers, particularly to allay the fears of adverse effects of INCS. The other barriers, such as running out of supply, can be overcome by posting medications directly to patients by the healthcare providers.
Keywords: Brief Medication Questionnaire; adverse effects; allergic rhinitis; comorbid medical diseases; immunoglobulin E; intranasal corticosteroids; medication adherence.