Effects of Preparatory Information on Anxiety and Treatment Adherence in Heart Surgery Patients

• Participant invitation The study invitation for the prospective participants who are patients scheduled for heart surgery is posted at the cardiothoracic surgery outpatient clinic. Before deciding, patients who are interested in participating can get in touch with the researchers to learn more about the study.

Additionally, the invitation will also be posted at the in-patient facilities where patients are being admitted for heart surgery so the nurses to ask patients for their interest in being the study volunteers. The researchers will be notified if there are potential participants.

• Recruitment and consent process The researcher will meet with prospective participants in in-patient units where they are being admitted for surgery to discuss the study details and evaluate the Abbreviated Mental Test for screening. Potential participants who have an AMT test score of less than 8 will be excluded and thanked for their volunteer. The consent will be signed by the patients who agree to participate. The meeting will take place between 6:00 and 8:00 p.m. after patients have completed all preoperative preparations and have had dinner.

• Research assistants Two research assistants in this study are registered nurses with more than 3 years of experience in caring for heart surgery patients. They were trained to follow the study protocol and use research instruments. The interrater reliability between the researchers and research assistants is 0.96. To avoid bias, the research assistants will evaluate the outcomes in both the experimental and comparison groups while remaining blind to group allocation.

• Sample size estimation The sample size estimation was calculated using the G*Power 3.1.9.7 program for a two-sample t-test for independent with 0.8 effect size from Cohen's d formula (Cohen, 1988) using mean anxiety from a similar study. The estimated sample size needed for this study is 21 for each group with 10% adjusted for attrition resulting in 24 participants necessary for each group to demonstrate an effect.

• Data collection Data collection starts once the participants sign the consent. The participants will be allocated to a group with computer computer-generated program. Allocation to the group cannot be concealed from the participants but will be blinded to the research assistants who evaluate the outcomes. In the experimental group, the researcher asks participants to rate their anxiety before receiving the intervention (12-minute preparation information video + usual preparation information) while in the comparison group, only usual preparation information is given. The participants rated their anxiety again 30 minutes after the intervention and the usual information was given. The experimental group will receive the preparation VDO again the day before surgery. Participants in both groups rate their anxiety 48 hours after surgery and are evaluated for treatment adherence during their ICU stay. Participants who are unable to participate until the completion of the trial for any reason will be withdrawn from the study and analysis. Individual participant identities will not be recorded or disclosed in any way. Data analysis will be used to identify groups, and all recorded information will be deleted two years after the study is completed.

• Data analysis The data analysis will be performed using the Statistical Package for the Social Sciences (SPSS) version 28 software with a confidence interval of 95% (α=0.05). Descriptive statistics, Chi-square test, ANOVA, and Mann-Whitney U test will be analyzed to evaluate demographic differences between the groups depending on the normality assumption. Repeated measures ANOVA and ANCOVA will be used to analyze differences in anxiety and treatment adherence within the groups and between the groups, respectively. However, if the normality assumption is not fulfilled, the Mann-Whitney U test and Chi-square will be performed.