Study title: Population-based cohort study of non-communicable diseases in Ravansar

Name and surname of the principal investigator, landline phone, e-mail and address:

Dr. Farid Najafi, Faculty of Health, Department of Epidemiology, Kermanshah University of Medical Sciences, Kermanshah, Iran. E-mail: farid_n32@yahoo.com

Dr. Yahya Pasdar, Faculty of Nutrition and Food Sciences, Department of Nutrition Sciences, Kermanshah University of Medical Sciences, Kermanshah, Iran. E-mail: yahya.pasdar@gmail.com

Year of study start: This study was started in 2014 in coordination with the Deputy for Research and Technology, Ministry of Health and Medical Education.

Study Phases:

Baseline Phase of the Ravansar Cohort Study: The Ravansar Cohort set-up began in January 2013 and continued until March 2013. The pilot phase, which began in August 2014, selected 1,100 individuals aged 35-65, and the questionnaires that were to be used in the main study were asked and completed in the aforementioned population. A number of questionnaires that needed to be reviewed and re-confirmed for their validity and reliability were examined. The strengths and weaknesses of completing the questionnaires and conducting clinical and biological tests were identified. After the pilot phase was completed, the main phase of the study began in 2016 and continued until 2016. In this phase, 10,000 individuals aged 35-65 were selected and entered into the study.

Follow-up phases of RaNCD Cohort Study: The follow-up phases of the study have started since 2016. Currently (June 2023), six follow-up phases have been completed, and the seventh and eighth follow-up phases are underway.

Reassessment phase of the RaNCD Cohort Study: Out of 10,000 participants in the baseline phase, 3,000 were randomly selected and examined in the reassessment phase. In this phase, all the information collected in the first phase of the study was repeated. This phase began in 2022 and ended in May 2023.

Scope of the study: The main focus of the Ravansar cohort study is on the prevalence, incidence, and risk factors of noncommunicable diseases such as cardiovascular diseases, diabetes, hypertension, metabolic syndrome, osteoporosis, rheumatoid arthritis, chronic pain, digestive problems, kidney failure, liver cirrhosis, nonalcoholic fatty liver, cancers, etc.

Population covered by the study: This study was conducted in Kermanshah province on permanent residents aged 35-65 of the city of Ravansar. The city of Ravansar is located in western Iran and close to Iraq in terms of geographical coordinates, and the people living in Ravansar are mostly of Kurdish ethnicity. According to the last census conducted (before the start of the study), the population of this city was close to 50 thousand people. In the first phase of the study, 10 thousand people aged 35-65 living in the city and villages of Ravansar were randomly selected and entered into the study.

Biobank specifications: RaNCD cohort study data were collected in four sections including laboratory, anthropometry, medical examinations and questionnaire.

In the laboratory, all sampling and isolation procedures were performed according to international standards, and the details of the sampling are given in the protocol of the first phase of the Persian Cohort Study. The biological samples collected in the cohort study included blood, urine, hair and nail samples. Blood samples in the form of serum, buffy coat, plasma and whole blood of 10,000 participants were stored. In the laboratory section, blood sugar, lipid profile, liver enzymes and CBC, urea and creatinine were measured. A total of 169,000 biological samples were stored in the Ravansar Cohort Study Biobank.

For the anthropometry section, all measurements were performed according to the protocol of the first phase of the Persian Cohort Study. The height of the participants was measured using the BSM 370 device (Biospace Co., Seoul, Korea) with an accuracy of one centimeter. A Bio Impedance Analyser BIA (InBody 770 Biospace, Korea) was used to measure anthropometric indices.

Blood pressure and heart rate were measured twice according to the "Blood Pressure Measurement Protocol in the Persian Cohort". Oral and dental examinations were performed by a physician at the cohort center.

A large amount of information was collected using a questionnaire, which is summarized as follows:

- General questionnaire (30 questions)

- Socioeconomic status questionnaire (29 questions)

- Fuel consumption and living area standards (9 questions)

- Lifestyle exposures including 13 questions

- Contact with animals (4 questions)

- Current job information (10 questions)

- Previous job history (3 questions)

- Physical activity (22 questions)

- Sleep habits (15 questions)

- Mobile phone use (6 questions)

- Pesticide use (38 questions)

- Past medical history (115 questions)

- Signs and symptoms of disease (57 questions)

- Past and current medication use (4 questions)

- Selected important medications (5 questions)

- Family medical history (55 questions)

- Fertility history (women) (34 questions)

- Contraceptive history (4 questions)

- Hormone replacement therapy (4 questions) Question)

- Physical Examinations (8 questions)

- Disability or Amputation (2 questions)

- Oral Health (14 questions)

- Personal Habits (14 questions)

- Smoking History (6 questions)

- Smokeless Tobacco History (6 questions)

- Medication History (7 questions)

- Alcohol History (6 questions)

- Dosage of Smoking, Medication, Alcohol (7 questions)

- Food Frequency (113 Food Items) and Native Foods (5 questions)

- Micronutrients (76 questions)

- Eating Habits (46 questions)

- Water Consumption (4 questions)

- Nutritional Supplements (23 questions)

The participants' responses are immediately recorded and stored online in an electronic database connected to the central server of the Persian Cohort. The Persian Cohort administrators and the Tehran Gastroenterology and Liver Research Institute are responsible for maintaining the data.

A total of 1186 variables have been collected in various sections of the cohort, including biochemical, hematological, anthropometric, and various questionnaires, and are stored as a biobank and database in university freezers and servers.

How to request the cohort data and materials

So far, eight calls for use of RaNCD cohort data have been posted on the website of the Vice Chancellery for Research & Technology of Kermanshah University of Medical Sciences. Researchers and research teams first register their proposed titles on the Persian Cohort website at https://www.persiancohort-portal.com/Account/Login?ReturnUrl=%2F. After the title is approved, the data will be made available to them within one to two weeks, based on the study objectives and the list of required variables they requested. Data analysis is performed by the data requesting team based on the proposed title and objectives under the supervision of the cohort administrators.