Adherence to Subcutaneous Immunotherapy (SCIT) During the COVID-19 Pandemic: The Impact of Anxiety and Depression

Objective: Allergen immunotherapy (AIT) is a cornerstone treatment for IgE-mediated allergic diseases and adherence to subcutaneous immunotherapy (SCIT) is essential for achieving optimal therapeutic outcomes. We aimed to evaluate SCIT adherence, identify the primary causes of treatment interruption, and investigate the relationship between anxiety/depression and SCIT adherence during the COVID-19 pandemic. Materials and Methods: This retrospective observational study included 191 patients underwent SCIT at a university allergy and immunology clinic between February 2021 and January 2022. Data were collected through structured face-to-face questionnaires assessing demographic characteristics, treatment duration, allergen type, comorbidities, SCIT interruption status, reasons for interruption, and symptom exacerbation. We evaluated the psychological status via the Hospital Anxiety and Depression Scale (HADS). Results: The mean age of participants was 35.9 ± 11.2 years, and 52.9% were female. A total of 70 patients (36.8%) interrupted SCIT during the pandemic. Analysis by allergen type revealed a statistically significant difference between pollen and mite groups (p < 0.001), whereas no significant differences were observed between venom and pollen or mite groups. Significant differences were identified between patients treated for ≤1 year and those receiving longer treatment durations (p < 0.05). However, no significant difference was found between treatment durations of 1–2 years and ≥3 years. These findings suggest that treatment duration has a more pronounced impact within the first year, while outcomes tend to converge with longer treatment periods. The most common reasons for treatment interruption were access difficulties (52.9%) and fear of infection (35%). Conclusion: Approximately one-third of patients discontinued SCIT treatment during the COVID-19 pandemic, primarily due to access-related challenges. Female gender and mite allergen immunotherapy were associated with higher rates of non-adherence.