Beta-thalassemia major is a chronic hereditary blood disorder that requires lifelong treatment, including regular blood transfusions and iron chelation therapy. Poor adherence to treatment remains a significant challenge and may lead to iron overload and related complications. Self-efficacy is an important factor influencing patients' ability to adhere to treatment recommendations.

This study aims to evaluate the effect of nurse-delivered Motivational Interviewing (MI) on treatment adherence and self-efficacy among Omani adults with beta-thalassemia major. A pre-experimental one-group repeated-measures design will be used. Approximately 45 participants will be recruited from the Oman National Center for Hematology and Bone Marrow Transplantation and Royal Hospital in Muscat, Oman.

Participants will receive three individualized MI sessions over a period of six to eight weeks. Treatment adherence and self-efficacy will be assessed at baseline, immediately after completion of the intervention, and at three-month follow-up. Secondary outcomes include serum ferritin level and frequency of thalassemia-related hospital admissions. The findings will provide evidence regarding the usefulness of motivational interviewing in improving adherence-related outcomes among adults with beta-thalassemia major.

Beta-thalassemia major is a lifelong transfusion-dependent condition that requires continuous adherence to iron chelation therapy to prevent iron overload and its associated complications. Despite advances in treatment, suboptimal adherence remains common among adults with beta-thalassemia major and contributes to increased morbidity and healthcare utilization. Self-efficacy has been identified as a key determinant of adherence behavior and may be enhanced through behavioral interventions.

This study will evaluate the effectiveness of a nurse-delivered Motivational Interviewing (MI) intervention on treatment adherence and self-efficacy among Omani adults with beta-thalassemia major. The study is guided by Social Cognitive Theory and uses a quantitative pre-experimental one-group repeated-measures design.

Eligible participants will be adults aged 18 years and older with beta-thalassemia major who are receiving regular follow-up and iron chelation therapy. Participants will be recruited from the Oman National Center for Hematology and Bone Marrow Transplantation, University Medical City, and Royal Hospital in Muscat, Oman.

The intervention consists of three individual motivational interviewing sessions delivered by a trained nurse over six to eight weeks. Each session will last approximately 30 minutes and will focus on exploring treatment-related challenges, enhancing motivation, strengthening self-efficacy, and supporting adherence to iron chelation therapy.

Primary outcomes include treatment adherence measured using the Arabic version of the Adherence to Refills and Medications Scale (ARMS) and self-efficacy measured using the Arabic version of the Self-Efficacy for Appropriate Medication Use Scale (SEAMS). Assessments will be conducted at baseline, immediately after the intervention, and three months after completion of the intervention.

Secondary outcomes include changes in serum ferritin levels and thalassemia-related hospital admission frequency. Data will be analyzed using descriptive statistics and repeated-measures statistical tests to examine changes across study time points.

The results of this study may support the integration of motivational interviewing into routine nursing practice for adults with beta-thalassemia major and contribute to improving patient-centered chronic disease management in Oman.

Inclusion Criteria:

• Adults aged 18 years and older.
• Diagnosed with transfusion-dependent beta-thalassemia major.
• Receiving iron chelation therapy for at least 6 months.
• Receiving regular follow-up at the participating study sites.
• Able to communicate in Arabic or English.
• Willing and able to provide informed consent.
• Able to attend the motivational interviewing sessions and complete study questionnaires.

Exclusion Criteria:

• Current hospitalization for an acute medical condition at the time of recruitment.
• Severe cognitive impairment or psychiatric illness that may affect participation.
• Participation in another structured psychosocial or behavioral intervention program.
• Unable or unwilling to provide informed consent.

Individual participant data will not be shared to protect participant confidentiality and privacy.