2.1. Study population:
The current census cohort study is part of the ST-elevated myocardial infarction cohort study in Isfahan (SEMI-CI) conducted on 867 patients with acute myocardial infarction (AMI) admitted at cardiology referral centers from September 2015 to October 2016. Figure 1 represents the details of the studied population.
The over-18-year-old hemodynamically stable patients diagnosed as AMI due to the manifestations of ST-segment elevation myocardial infarction (STEMI) or new-onset left bundle branch block (LBBB) were included. The AMI occurrence during a balloon angioplasty procedure, the simultaneous presence of other major medical conditions (e. g. chronic kidney, liver, thyroid, and brain-related diseases), and major psychiatric disorders were considered the exclusion criteria.
The study population was included through convenience sampling from all of the patients who met the inclusion criteria. In this term, a trained nurse gathered the patients' medical and demographic information from the hospital medical archives and then interviewed them to fill the psychosomatic questionnaires.
The study follows the guidelines for reporting cohort studies according to STROBE checklist (See Supplementary File 1).
2.2. Ethical considerations and writtern consent:
The university ethics committee approved the study proposal. After that, the study protocol was explained for the eligible patients, they were reassured about the confidentiality of their personal information, and eventually, written consent for participation in the study was obtained.
2.3. Primary assessments:
An overview:
The patients were primarily diagnosed as AMI due to the definitions, including manifestations of ST-segment elevation myocardial infarction (STEMI) in two or more echocardiogram leads indicating a particular epicardial involvement territory or new-onset left bundle branch block (LBBB).
After the admission, all of the required interventions were performed as soon as possible. Then, the patients were admitted to the cardiac care unit (CCU) until achieving the desired stability in hemodynamic. Following this stability, we proposed our request to fill the questionnaires designed for the study.
The latter obtained information at discharge includes EF based on echocardiography, weight, height, body mass index (BMI), systolic (SBP), and diastolic blood pressure (DBP), and hyperlipidemia. The information of performed intervention, percutaneous coronary intervention (PCI), or coronary artery bypass grafting (CABG), were recorded in the checklist, as well.
Follow up assessment:
The patients were followed annually for two years through telephoning and invitation for an in-person visit with a cardiologist. At the appointment, the cardiologist assessed the patient's blood pressure (BP) and ejection fraction (EF) (by echocardiography) based on standard protocols and recorded in the study checklist. Besides, a thorough physical examination, the evaluation of drug history, and adherence to the medications were assessed.
Besides, a trained nurse recruited information about medication adherence, and a trained physician gathered the data about Major Adverse Cardiovascular Events (MACE) occurrence in the study population. The term "MACE" refers to atherosclerosis cardiovascular diseases (ASCVD) in coronary and cerebral vessels, including non-fatal MI, non-fatal stroke, and ASCV deaths. In the case of death, hospital records, verbal autopsies, and death certificates were utilized for recruiting further details. The consistency of death records with hospital medical documents was interpreted and confirmed by a panel consisting of two cardiologists and a neurologist.
2.4. Measurements:
Demographic information:
This study's obtained demographic information included age, gender, and marital status; all were recruited from the patient's medical records existed in the hospital. In cases with incomplete medical records, the demographic information was obtained through either telephoning or follow-up visits.
Medical history:
The patients' clinical history, including the previous history of myocardial infarction, diabetes mellitus, and hypertension, was gathered from the hospital medical records. The information about the involved epicardial territory(s) based on the coronary angiography and ejection fraction (EF) at discharge was recruited from the hospital's medical documents.
In addition, the severity of AMI was assessed by the consideration of the involved epicardial territory(s) (stenosis in more than 75% of the vessels) and the EF at discharge. Therefore, the AMI was more severe by increasing the numbers of involved epicardial territories and a more noticeable reduction in the EF.
Besides, the patient's blood pressure and EF (through echocardiography) were re-evaluated based on the standard protocol in the two-year follow-up visit, as well.
The Diagnostic Criteria for Psychosomatic Research:
The Criteria for Psychosomatic Research (DCPR) questionnaire was used to assess the psychosomatic factors. This questionnaire includes a set of 12 clusters assessing different categories of psychosomatic manifestations. Four clusters target perceiving and responding to health status; four ones assess the concept of somatization, and the latter four ones consider the consistent and frequent psychosomatic dimensions detected in medical patients. The original version of DCPR has shown the generally substantial interrater agreement for all 12 syndromes (all κ values >0.61) and perfect agreement for 9 of the assessed clusters (κ > 0.81).
In the current study, we proposed 4 clusters, including health anxiety (4 questions), illness denial (3 questions), irritable mood (5 questions), and demoralization (5 questions). The results were interpreted qualitatively, whether a disorder is present or not.
Sense of Coherence questionnaire:
We used the 13-item questionnaire to evaluate the patients' SOC; Erikson and Lindstrom primarily validated the questionnaire in 2005. The 13-item SOC questionnaire is rated based on a 7-score Likert scale assessing three aspects of comprehensibility (5 items), manageability (4 items), and meaningfulness (4 items). The responses to questions number 1, 2, 3, and 7 should be scored inversely. The questionnaire's final scores ranged from 13 to 91 in total, while the scores of each subscale, comprehensibility, manageability, and meaningfulness can be measured separately. The validated versions of the 13-item SOC questionnaire in the literature had the alpha Cronbach's ranging from 0.70 to 0.92(16). Mahammadzadeh and colleagues validated the Persian version of this means in 2010 that revealed the remarkable Cronbach's alpha of 0.77(17).
In the current study, we have made a reference range of 52 to divide the patients into the two groups of a low and high sense of coherence, as those with the scores above 52 are considered high, and the remaining ones as a low sense of coherence.
2.5. Statistical analysis:
The obtained data were entered into the Statistical Package for Social Sciences (SPSS; version 15.0, SPSS Inc., Chicago, IL, USA). The descriptive data were presented in mean, standard deviation, absolute numbers, and percentages. In order to compare the frequencies between the groups, the chi-square test was utilized. The continuous variables were compared using the t-test.
Binary logistic regression analysis was applied to find the association between MACE and SOC level in crude (model 1) and adjusted models, including demographic factors, patients' medical history, clinical follow-up assessments, and contributing psychosomatic factors (health anxiety, illness denial, irritable mood, and demoralization). Linear logistic regression analysis with similar models was applied to assess the SOC score association with the mentioned factors. Odds ratios (ORs) and ORs per SD were reported with the corresponding 95% confidence intervals (95% CIs). P-value of less than 0.05 was considered as a significant level.