Study design
The present study was a non-randomized controlled trials study which is registered with in Iranian Registry of Clinical Trials (IRCT20140307016870N6), on (14.06.2020). This research conducted in Afshar Heart Rehabilitation Center of Yazd, Iran which compared control and experimental groups. Our study adheres to CONSORT guidelines and the intervention is described in accordance with the CONSORT checklist (Figur1).
The research samples were selected from patients with heart problems who were discharged from Afshar Hospital in Yazd, Iran and referred to the rehabilitation center using a purposive sampling method based on inclusion and exclusion criteria.
Inclusion criteria:
Inclusion criteria were cardiovascular diseases requiring CR, age of 18 years and older, familiarity with the Persian language, and consent to participate in the study.
Exclusion criteria:
Exclusion criteria were sleep disorder requiring medication before the rehabilitation, history of hypnotic drug use for more than 6 months, history of depression and anxiety according to psychiatrist, cognitive impairment (vision or hearing problem), lack of participation in more than a session, loss of consciousness during the intervention, exacerbated patient clinical condition during CR and canceling the continuation of study.
Sample size
The Sample size was equal to base on a study by Lin et al. (2016). See equation in the supplementary files.
Considering type 1 error equal to 0.05 and power of test equal to 0.95, it was obtained equal to 35 considering 25% non-response probability [20].
Procedure
Patients who participated in the rehabilitation program were considered as the experimental group, and patients who did not participate in the rehabilitation program or left the program despite being taught the need for rehabilitation were assigned to the control group. In both groups, the selection of samples continued until a sample size of 35 was achieved. After selecting patients and obtaining informed consent to participate in the study, participants' demographic characteristics and patients' SQ were completed using the Pittsburgh Sleep Quality Index (PSQI). Based on a complete examination and results of the initial exercise test of patients, having a companion, and other factors such as a history of heart surgery and myocardial infarction and patients' risk levels, the clinician specified the length and speed of exercise with treadmill and exercise program for any patient in the experimental group to perform the rehabilitation program. Accordingly, the intensity of training in the initial sessions started from 20% to 40% of the reserve heart rate and gradually increased to 60% in the last sessions. The CR program included 12 weeks of exercise, 3 sessions per week, and 3 sessions of training programs each for 45 minutes. Three collective question and answer sessions and lecture training were held by a team including a physician, nutritionist, psychologist, and health educator with an emphasis on the role and importance of CR in patients' recovery after cardiac surgery, strategies for correcting cardiac risk factors, diet modification, and adopting a healthy lifestyle including quitting smoking and exercise, improving quality of life, adapting to pain, anxiety, depression, postoperative problems, and sexual activity of patients after a heart attack; then, educational pamphlets were provided for patients. The patients' spouses or families were also invited to participate in training sessions to encourage home exercises and provide social support.
In addition, a special sleep improvement program was implemented in two 45-minute sessions for patients. It provided an explanation of 1- Definition of sleep and importance of adequate sleep, 2- Different types of SD, 3- Determination of sleep characteristics and habits, 4- Identification of a wrong behavioral pattern relating to sleep, and 5- Useful methods of controlling SD, especially sleep improvement methods in heart patients. Furthermore, videos and photos were displayed, and their experiences were discussed. Due to the fact that the rehabilitation program usually lasts for 3 months, the questionnaires were completed face-to-face for the experimental group and by phone for the control group after this time.
Instruments
The data collection tool included a demographic and clinical profile form (age, sex, marital status, smoking, and diagnosis of current disease) and the Pittsburgh Sleep Quality Index (PSQI) [21]. The PSQI examines the quality of sleep over the past month. It has 9 items. Item 5 has 10 sub-categories that provide a general description of SQ, sleep delay, useful sleep duration, the ratio of useful sleep duration to the total time spent in bed, sleep disorder, and waking up due to the shortness of breath, nocturnal cough, body aches, extreme cold, extreme heat, use of sleeping pills to fall asleep, drowsiness, and inability and non-motivation to exercise during the day caused by insomnia. All 19 items were given three types of scores to score the PSQI. Note: Getting a total score above 5 in the whole PSQI means poor SQ[22]. The PSQI is a standard PSQI for assessing SQ over the past month. The validity and reliability of the PSQI have been proven in several studies. Buysse et al. reported the internal validity of α=0.83 and reliability in the re-test to be r=0.85[21]. Parker et al. also reported a sensitivity of 90% and specificity of 87%[23]; Bertolazi et al. reported the reliability coefficient of r=0.82 with high validity[24]. Furthermore, the reliability of the PSQI was obtained equal to r=0.88 by Hosseinabadi et al. in Iran[25]. Soleimani et al. measured the reliability of PSQI equal to r=0.85[26]. The PSQI is available at the following web address: https://www.psychiatry.pitt.edu/sites/default/files/inline-files/PSQI%20Article.pdf [21].
Statistical analysis
Data analysis was performed using SPSS16. The mean and standard deviation were used to describe quantitative variables of the study in two groups according to the normality of error in variables. The frequency and percentage were reported for qualitative variables. Kolmogorov – Smirnov test was used to determine the normality of the data distribution. Independent t-test and paired t-test were used to perform the relevant inferential statistics for comparing the mean scores of SQ in both groups and according to the normality of SQ score in each group (P=0.05).
Ethical approval, informed consent and trial registration
The present study was approved with a code of ethics (IR.SSU.REC.1398.200) on 14 January 2020 by the Ethics Committee of Shahid Sadoughi University of Medical Sciences in Yazd. Written consent was obtained from participants in the interventional group. Also, Oral consent was obtained from the participants in the control. This study is registered at ClinicalTrials.gov, IRCT20140307016870N6, on 14 September 2020.