Study design, aims, and participants information
In this cross-sectional study, we studied a cohort of individuals that are parts of a larger prospective epidemiological research in Iran (the Azar Cohort Study) (20). The current study was carried out on healthcare workers in 2020 as a part of the Azar cohort study, which was conducted by the liver and gastrointestinal diseases research center of Tabriz University of Medical Sciences (TBZMED) (21).
The purpose of this cohort study was to evaluate 3000 participants, including healthcare employees in hospitals, schools, and health networks of TBZMED. A total of 500 persons participated in this study. Our baseline assessment consisted of a face-to-face health interview or a health examination regarding a broad range of established and novel risk factors for NCDs.
Eligibility criteria
Participants of this study include full-time and long-term contract employees aged 18 to 75 years who are not pregnant or breastfeeding, and who are not planning to retire within the next five years. Patients who reported a history of debilitating psychiatric disorders or physical illnesses by a health professional were excluded from this study.
Ethical considerations
All involved participants provided written informed consent, and the Institutional review board (IRB) of TBZMED (IR.TBZMED.REC.1396.1263) approved the study.
Main variables
Age, sex, systolic blood pressure, diastolic blood pressure, diabetes, smoking, hypertension, statin, metabolic syndrome, HDL cholesterol, LDL cholesterol, total cholesterol, triglycerides, hemoglobin, and hematocrit circumference were assessed and analyzed in our PLA model.
Demographic Characteristics of the Participants
We used a questionnaire for evaluating the demographic characteristics, including age (years), sex (1: Male, 2: Female), marital status (1: Single, 2: Married, 3: Widow, 4: Divorce, 4: Other), and educational level (1: Illiterate, 2: Primary, 3: Secondary, 4: High school graduated, 5: Associate degree, 6: Bachelor, 7: Master, 8: PhD). Moreover, lifestyle patterns, i.e., smoking (1: Past or current, 2: Never), diabetes (1: Yes, 2: No), hypertension (1: Yes, 2: No), statin (1: Yes, 2: No), metabolic syndrome (1: Yes, 2: No), drug use (1: Daily, 2: Weekly, 3: Monthly), hookah use (1: Past or current, 2: Never), alcohol consumption (1: Past or current, 2: Never), were also assessed by the questionnaire.
Measurements
Height is recorded to the nearest 0.5 cm using a mounted tape measure, subjects without shoes and their arms hanging freely by their sides. Barefoot subjects with only light clothing have their weight recorded to the nearest 0.1 kg on a Seca scale (Seca®, Germany). Body mass index was determined using the standard formula, i.e., weight (kg)/height2 (m) (21). Waist of subjects is measured according to the USA National Institutes of Health (NIH) guidelines. Blood pressure was measured by a trained nurse twice with a two-minute interval, i.e., twice for each arm in a sitting position after 10 minutes of rest using a mercury sphygmomanometer (Rudolf Richter, DE-72417, Germany). Lipid profiles (total cholesterol, high-density lipoprotein cholesterol (HDL-cholesterol), and triglycerides) were assessed using serum samples, which were analyzed using Miura One automated equipment (I.S.E., Rome, Italy) and a commercial DiaSys kit (DiaSys Diagnostic Systems, Hamburg, Germany) (22). Low-density lipoprotein cholesterol (LDL-cholesterol) was calculated according to the Fried Ewald equation (23). Hematocrit was measured using (EKF Diagnostics UltraCrit ™ Hematocr, USA). A photometric device (HemoCue® Hb 201+) is used to determine the hemoglobin content of the blood (24). Insulin was measured with an enzyme immunoassay (microtiter plate format; Dako Diagnostics, Ely, United Kingdom).
Sample size
The census was conducted during a specific period on all eligible health care providers, official staff, and lecturers of Tabriz University of Medical Sciences.
Statistical analysis
Continuous variables are presented as mean and standard deviation (SD) and categorical variables as the frequency count and percentage. The continuous variables were checked and confirmed for normality by distribution measures, namely skewness within ±1.5 and kurtosis within ±2. Chi-square tests with exact p-value and one-way analysis of variance (ANOVA) followed by Tukey post hoc test were used to assess the difference among high risk and low risk factors, for categorical and normal continuous variables, respectively. We used the Akaike information criterion (AIC), Bayesian information criterion (BIC) and Adjusted Bayesian information criterion (ABIC) To compare and select the best-fitted model. For these statistics, the smaller values show better fit of the model. Each class was described in terms of entropy measurements that ranges from 0.00 to 1.00, and also sociodemographic factors. Furthermore, the LPA-driven classes were subsequently entered into a logistic regression model (backward LR) to test for associations between each class and the risk of cardiometabolic with adjustment for smoking, HDL cholesterol, triglyceride, BMI, and other clinical variables. The significance thresholds for variables were set at P <0.05. LPA was performed using MPlus 7.4 (Muthen and Muthen, Los Angeles, CA, USA) and the other analyses using SPSS 17 (SPSS Inc., Chicago, IL, USA) software.