Real-life adherence to subcutaneous immunotherapy: What has changed in the era of the COVID-19 pandemic

BACKGROUND: Allergen immunotherapy (AIT) must be continued for 3 years, to achieve a long-term modifying effect. Adherence is a key to ensure effectiveness. The objective of this study was, first of all, to evaluate the adherence with subcutaneous immunotherapy (SCIT) and to identify the main causes of SCIT withdrawal in real-life practice in our clinic. Secondly, we also aimed to investigate to what extent the COVID-19 pandemic altered our SCIT receiving patients’ treatment adherence behaviors and the factors that affected their decisions. METHODS: Retrospective analysis of the medical records of patients ages ≥18 years, who had started SCIT in January 2014 or later until September 2020 in our department for the diagnosis of allergic rhinitis, allergic asthma or venom allergy, were included in the study. Adherence was determined as the accomplishment of 3 years of SCIT. RESULTS: A total of 124 patients (72 female [58.1%]; median age, 35 [19–77] years) were included. The adherence rate to SCIT in our tertiary center's real-life setting was 56.25% with a follow-up duration of 3 years before COVID-19 pandemic. Dose modification, defined as reducing patient's planned SCIT dose due to a systemic allergic/large local reaction or missed injection, and its frequency, which is the number of dose adjustments done throughout the SCIT, was found to be the only factor related to nonadherence. But with the pandemic only in 6 months, among 63 patients receiving SCIT, 15 patients (23.81%) dropped out, and the most common reason was fear of being infected with COVID-19 virus during receiving SCIT in hospital (93.33%). The only independent predictor of drop-out during the COVID-19 pandemic was short duration of AIT (p = 0.012). When we compare the dropped-out cases before and after the start of pandemic, AIT duration was significantly shorter in pandemic period (p = 0.005). CONCLUSION: Adherence rate to SCIT in our real-world setting study was 56.25% before the COVID-19 pandemic. Our results indicated that patients requiring dose modification were more prone to be non-adherent. Approximately one quarter of patients dropped-out with the start of pandemic, almost all due to fear of being infected during receiving SCIT in hospital. Since short SCIT follow-up time was found to be the only risk factor for drop-out during the COVID-19 pandemic, we believe that patients who are in the early phases of their treatment should be observed more closely and their concerns should be answered by their doctors.