Adherence to prophylaxis in adult patients with severe haemophilia A

Introduction: Adherence is a cornerstone of factor VIII prophylactic treatment. Information regarding the factors with potential influence on adherence is limited, particularly in adult patients.Aim: To assess adherence in adult patients with severe haemophilia A receiving prophylactic treatment in a real-life setting, and investigate the factors influencing adherence.Methods: Observational, prospective study including adult patients receiving factor VIII therapy in 15 Spanish centres. Patients recorded infusion doses on a logbook and answered various questionnaires to assess their health beliefs. Adherence rate was the percentage of infused doses over the prescribed ones. Self-perceived adherence was assessed using the VERITAS-Pro questionnaire, the psychometric properties of which were validated in the Spanish population. The relationship between adherence rate and treatment, clinical and demographic characteristics, health beliefs and perceived self-efficacy was investigated.Results: A total of 66 patients were followed up for 12 months. Mean adherence rate at the end of follow-up was 82.5%. Most of the study patients (n = 53, 80.3%) showed a moderate-to-high adherence rate (>70%). The VERITAS-Pro revealed a high perception of adherence. Multivariate analyses to predict treatment adherence identified the knee as a target joint and longer treatment duration as variables with significant (negative) influence on adherence. Adherence rate was not influenced by the patient's health beliefs or perceived self-efficacy.Conclusion: Most adult patients receiving factor VIII prophylactic treatment in Spain have moderate-to-high treatment adherence. Treatment duration and the knee as a target joint are factors with a moderate negative influence on treatment adherence.