This descriptive study aims to examine the relationship between self-efficacy and medication adherence in individuals with coronary artery disease (CAD). The study will be conducted between March and October 2025 at Adıyaman University Training and Research Hospital with a planned sample size of 135 participants. Data will be collected using a Descriptive Information Form, the Self-Efficacy for Managing Chronic Disease Scale, and the Medication Adherence Report Scale (MARS).

Coronary artery disease (CAD) remains one of the leading causes of death worldwide. Managing CAD requires long-term treatment adherence and lifestyle changes. Self-efficacy, which reflects an individual's belief in their ability to perform specific health behaviors, plays a key role in disease management. In CAD patients, high levels of self-efficacy have been associated with better treatment adherence, improved symptom management, and successful adoption of healthy behaviors.

This descriptive study is designed to investigate the relationship between self-efficacy and medication adherence in individuals diagnosed with CAD. The study will be carried out at Adıyaman University Training and Research Hospital between March and October 2025. The target population includes patients who have been diagnosed with CAD (e.g., angina pectoris, myocardial infarction) for at least one year and meet the inclusion criteria. Based on a power analysis using G*Power software (effect size f² = 0.15, α = 0.05, power = 0.90), the required sample size is calculated as 112. However, accounting for possible data loss or participant dropout, the final sample size is set at 135.

Data collection tools include:

Descriptive Information Form to assess demographic and clinical characteristics,

The 6-Item Self-Efficacy for Managing Chronic Disease Scale, validated in Turkish by İncirkuş and Özkan Nahcivan (Cronbach's alpha = 0.90),

Medication Adherence Report Scale (MARS), adapted to Turkish by Temeloğlu Şen et al. (Cronbach's alpha = 0.78).

The findings are expected to contribute to the literature and guide healthcare professionals, particularly nurses, in planning educational and counseling services to improve self-efficacy and medication adherence among CAD patients.

Inclusion Criteria:

• Being 18 years of age or older

Having been diagnosed with Coronary Artery Disease (angina pectoris, unstable angina, myocardial infarction) at least 1 year ago

Being followed

Being able to communicate in Turkish

Voluntarily agreeing to participate in the study

Having no diagnosed mental disorder

Exclusion Criteria:

• Having a primary diagnosis other than Coronary Artery Disease

Being unable to complete the questionnaires due to mental health problems

Providing incomplete data or withdrawing from the study

The study population consists of individuals aged 18 and older who have been diagnosed with coronary artery disease for at least one year and are being followed in cardiology or cardiovascular surgery outpatient/inpatient clinics at Adıyaman University Training and Research Hospital. All participants must be able to communicate in Turkish, have no diagnosed mental disorder, and voluntarily agree to participate in the study.

This study does not plan to share individual participant data (IPD).