This study aims to develop and validate an index measurement tool to assess the patient's self-care self-efficacy in managing oral anticoagulation therapy (OAC). The index measure (i.e., SCSE-OAC) will be tested for its cross-cultural validity and reliability for the English and Italian-speaking population. For these reasons, a multi-phase and mixed-method observational and cross-sectional study design will be conducted.

Oral anticoagulation therapy (OAC) is the most suitable treatment worldwide for the primary and secondary prevention of thromboembolism and stroke in patients with non-valvular atrial fibrillation (NVAF). However, the strategies to provide an optimal quality of anticoagulation control are still an open challenge for healthcare professionals. In this regard, understanding the health determinants underline the patient's adherence is fundamental in the research field to develop personalized patient-centered education interventions in clinical practice and consequently avoid low treatment adherence. Among these health determinants (e.g., patients' knowledge, health literacy, beliefs, etc), the patients' self-efficacy is underreported because a specific tool is not yet available to measure patients' self-efficacy regarding the health behaviors challenges in OAC self-care management.

The primary aim of this study is to develop the patients' self-care self-efficacy index in oral anticoagulation therapy management (SCSE-OAC) in adults with non-valvular atrial fibrillation and provide cross-cultural validity and reliability of the developed index measure.

More specifically, to assess the internal validity of the SCSE-OAC, content and construct validity proprieties will be tested for each translated version of the SECSE-OAC, as well as its reliability and invariance characteristics.

Inclusion Criteria:

• Age ≥ 18 years
• Diagnosis of non-valvular atrial fibrillation
• Outpatients
• Treating with any OAC for at least three months before enrollment
• Patients willing to participate in the study and provide informed consent

Exclusion Criteria:

• Patients treated with OAC for a brief period (i.e., less than three months)
• Patients with serious comorbidity (i.e, Charlson Comorbidity Index, ICC > 4)
• Patients who have suspended OAC for surgery in the last three months
• Cognitive impairment (assessed using six-item screener, SIS < 4)

Each native-speaking country involved in the study will select a convenience sample of adult non-valvular atrial fibrillation patients (NVAF) chronically treated with oral anticoagulants.