Study design and participants
This is a cross-sectional analysis of the Ravansar Non-Communicable disease (RaNCD) cohort study. The RaNCD study is one out of the seventeen sites of prospective epidemiological research study in Iran (PERSIAN). Ravansar is a district with a population of about 50,000 people, located in western Iran and in Kermanshah province. The number of participants in the baseline phase of the RaNCD was 10,000 adults, who all of whom were permanent residents of Ravansar. Details of the RaNCD methodology has been described elsewhere[19].
All subjects in the initial phase of RaNCD entered the present study. According to the objectives of the present study, subjects with cancer (n=85), renal failure (n=64), kidney stones (n= 1794), pregnant woman (n=138) and cases with missed information (n=638) were excluded from the study due to drug interactions and their effect on the occurrence of CVDs; as well as anthropometric changes, especially in pregnant women.
Data collection
All interviews were conducted by trained and face-to-face individuals at the RaNCD cohort Study Center. Demographic information including age, sex, marital status, level of education, place of residence (urban, rural), history of chronic diseases, smoking and alcohol consumption were recorded online in an electronic data collection form. Biochemical parameters, anthropometric indices and blood pressure were measured according to the cohort protocol.
Persian cohort physical activity questionnaire was used to assess physical activity in participants. This questionnaire included 22 questions about the amount of different daily activities of the subjects during the day; the answers to these questions were recorded in hours or minutes per day in the questionnaire. Finally, the questionnaire information was extracted and used based on met/ hour per day.
Biochemical and anthropometric measurements
To measure biochemical markers including TG and HDL-C, blood samples were collected after a 12 hours fasting. AIP was calculated by using the following formula: log10 (TG/HDL-C)[14]; and can be classified based on the values obtained: −0.3 to 0.1 for low risk, 0.1 to 0.24 for moderate, and more than 0.24 for high risk of CVDs[20].
Body weight was measured using Bio-Impedance Analyzer BIA (Inbody 770, Inbody Co, Seoul, Korea) with a precision of 0.5 kg. Other anthropometric measurements including body fat mass (BFM), percent body fat (BF %), skeletal muscle mass (SLM) and visceral fat area (VFA) were also measured with BIA. The height of the participants were measured with BSM 370 (Biospace Co, Seoul, Korea) with a precision of 0.1 cm. BMI was calculated weight (kg) divided by the square of height (m). WC was measured with a flexible measuring tape at a level midway between the lower rib margin and the iliac crest to the nearest 0.5 cm. VAI was measured by
Definition
CVDs: According to the RaNCD cohort study protocol, CVDs cases were those have a history of hospitalization and / or treatment of one or more heart conditions including stroke, Myocardial infarction (MI) and coronary artery disease (CAD), and / or current use of medication for CVDs.
Hypertension: Cases with SBP≥ 140 and DBP≥ 90 or current use of medication for hypertension. Hyperlipidemia: Cases that are currently taking medication for lipid disorders.
Obesity: Individuals with the BMI over 30 were considered obese.
Data analysis
Data analysis was performed using Stata version 14.1 software (Stata Corp, College Station, TX, USA). Findings from continues variables are presented as mean±standard deviation and categorical variables as frequency (percent). The normality of the data was assessed by Kolmogorov–Smirnov test. According to the binary outcome (CVDs), we used simple and multiple logistic regression models to assess the effect of AIP and VAI on CVDs separately. Variables with p-value<0.2 in univariable analysis were entered into multivariable logistic model. All statistical tests with 95% confidence interval and P value less than 0.05 were considered as statistically significant.