Validity and reproducibility of the PERSIAN Cohort food frequency questionnaire: assessment of major dietary patterns.

BACKGROUND: Dietary patterns, encompassing an overall view of individuals' dietary intake, are suggested as a suitable means of assessing nutrition's role in chronic disease development. The aim of this study was to evaluate the validity and reproducibility of a food frequency questionnaire (FFQ) designed for use in the Prospective Epidemiological Research Studies in IrAN (PERSIAN), by comparing major dietary patterns assessed by the FFQ with a reference method. METHODS: Study participants included men and women who enrolled in the PERSIAN Cohort Study at seven of the eighteen centers. These centers were chosen to include dietary variations observed among the different Iranian ethnic populations. Two FFQ were completed for each participant over a one-year study period (FFQ1 upon enrollment and FFQ2 at the end of the study), with 24 interviewer-administered 24-hour dietary recalls (24 h) being completed monthly in between. Spearman correlation coefficients (SCC) were used comparing FFQs 1 and 2 to the 24 h to assess validity, while FFQ1 was compared to FFQ2 to assess reproducibility of the questionnaire. RESULTS: Three major dietary patterns-Healthy, Low Protein/High Carb and Unhealthy-were identified, accounting for 70% of variance in the study population. Corrected SCC ranged from 0.31 to 0.61 in the validity and from 0.34 to 0.57 in reproducibility analyses, with the first two patterns, which accounted for over 50% of population variance, correlated at above 0.5 in both parameters, showing acceptable findings. CONCLUSIONS: The PERSIAN Cohort FFQ is suitable for identification of major dietary patterns in the populations it is used for, in order to assess diet-disease relationships.

Validity and reproducibility of a food frequency questionnaire assessing food group intake in the PERSIAN Cohort Study.

Purpose: A semi-quantitative food frequency questionnaire (FFQ) was developed for use in the Prospective Epidemiological Research Studies in IrAN (PERSIAN Cohort), investigating non-communicable disease risk factors. This study aimed to assess the validity and reproducibility of this FFQ, through food group intake. Methods: Participants, recruited from seven PERSIAN cohort centers, completed the FFQ at the beginning of the study (FFQ1) and at the end (FFQ2), with a 12-month interval in between, during which two 24-h dietary recalls (24 h) were completed each month. Correlation coefficients of the median intake of food groups recorded by the FFQs were compared to those of the 24 h to assess validity, and the two FFQs were compared to assess reproducibility of findings. Results: Overall, data from 978 participants were included in this validation analysis. Of the 26 food groups assessed, Tea, Sugars, Whole/Refined Grains, and Solid Fats/Oils, had the strongest correlations (0.6-0.79), while Red Meat, Chicken and Eggs showed moderate correlations (0.42-0.59). The weakest correlations observed belonged to Fresh fruit Juice and Other Meats (0.23-0.32). Reproducibility was assessed among those who completed both FFQ1 and FFQ2 (n = 848), revealing moderate to strong correlations in all food groups, ranging from 0.42 in Legumes to 0.72 in both Sugar and Sweetened Drinks. Conclusion: The PERSIAN Cohort FFQ is appropriate to rank individuals based on food group intake.

The Association between DASH Diet Adherence and Cardiovascular Risk Factors.

Background: The dietary approaches to stop hypertension (DASH) encourages high fruit, vegetable, and lean protein consumption and low salt, red meat, and fat intake to prevent or treat hypertension. However, besides hypertension, adherence to this diet has been shown to decrease other cardiovascular risk factors. Methods: This study assessed the relationship between the DASH diet and cardiovascular risk factors in a cross-sectional study of 2,831 adults chosen by multistage cluster sampling from 27 counties of Khuzestan province, Iran. DASH scores were calculated using data obtained from a qualitative food frequency questionnaire. Regression models were used to evaluate the association of DASH scores and common cardiovascular risk factors. Results: Significant trends were observed across quintiles of DASH scores for systolic blood pressure, fasting blood sugar, triglyceride, total cholesterol, and its components (p < 0·05). After adjusting for potential confounders such as sex, age, ethnicity, residence, wealth score, physical activity, energy intake, and family history of heart disease, the multiple regression analysis for each cardiovascular risk factor revealed that being in the highest quintile of total DASH score (OR = 0.72, 95% CI 0.52-0.99) was negatively associated with hyperglycemia. Conclusions: This study showed a positive relationship between DASH diet adherence and lower serum levels of glucose, triglycerides, and cholesterol. Prospective studies are needed to confirm these findings.

Gut microbiota profile in patients with nonalcoholic fatty liver disease and presumed nonalcoholic steatohepatitis.

Background: The main composition of intestinal microbiota in nonalcoholic fatty liver disease (NAFLD) and nonalcoholic steatohepatitis (NASH) patients has not yet been elucidated. In this, case-control study, we identified differences of intestinal microbiota in male patients with NAFLD, presumed NASH, and healthy controls. Materials and Methods: We compared gut microbial composition of 25 patients with NAFLD, 13 patients with presumed NASH, and 12 healthy controls. Demographic information as well as clinical, nutritional, and physical activity data was gathered. Stool and blood samples were collected to perform the laboratory analysis. The taxonomic composition of gut microbiota was assessed using V4 regions of microbial small subunit ribosomal Ribonucleic acid genes sequencing of stool samples. Results: Firmicutes, Actinobacteria, and Bacteroidetes were the most frequently phyla in all groups. Our results revealed that Veillonella was the only genus with significantly different amounts in presumed NASH patients compared with patients with NAFLD (P = 2.76 × 10-6, q = 2.07 × 10-4, logFC = 5.52). Conclusion: This pilot study was the first study to compare gut microbial composition in patients with NAFLD and presumed NASH in the Middle East. Given the potential effects of gut microbiota on the management and prevention of NAFLD, larger, prospective studies are recommended to confirm this study's findings.

Association between Sleeping Patterns and Mealtime with Gut Microbiome: A Pilot Study.

BACKGROUND: Disruptions in sleep related to mealtime may contribute to gut microbial imbalances, and put individuals at higher risk for metabolic diseases. The aim of this pilot study was to investigate the relationships between late-night eating habits and sleep quality and duration, with gut microbiota (GM) profiles. METHODS: In this cross-sectional study, 36 men referred to a clinic were enrolled. In addition to demographic information, each participant completed questionnaires regarding medical history, physical activity, late-night eating habits, sleep quality and sleep duration. The scores from these questionnaires were used to categorize study participants into the following groups: sleep quality (good or poor), late-night eating (yes or no) and sleep duration (<7 or ≥7 hours). Five grams of stool was also obtained from each participant for GM profiling analysis by sequencing. RESULTS: The mean age of the study population was 42.1 ± 1.6 years. Firmicutes and Actinobacteria were the two dominant phyla present in all participant samples. Differences in the relative abundance of GM at each taxonomic rank between study groups were insignificant. Only Erysipelotrichales at the order level were found to be significantly different between individuals who had late-night eating habits and those who did not (P & q < 0.05). No other parameter demonstrated a significant difference in GM profiles of participants. CONCLUSION: In this pilot study, we found Erysipelotrichales to be more abundant in individuals with late-night eating habits. Studies with higher sample sizes are warranted to better delineate the possible effects of time of eating on microbial composition.

Socioeconomic inequalities in prevalence, awareness, treatment and control of hypertension: evidence from the PERSIAN cohort study.

BACKGROUND: Elevated blood pressure is associated with cardiovascular disease, stroke and chronic kidney disease. In this study, we examined the socioeconomic inequality and its related factors in prevalence, Awareness, Treatment and Control (ATC) of hypertension (HTN) in Iran. METHOD: The study used data from the recruitment phase of The Prospective Epidemiological Research Studies in IrAN (PERSIAN). A sample of 162,842 adults aged > = 35 years was analyzed. HTN was defined according to the Joint National Committee)JNC-7(. socioeconomic inequality was measured using concentration index (Cn) and curve. RESULTS: The mean age of participants was 49.38(SD = ± 9.14) years and 44.74% of the them were men. The prevalence of HTN in the total population was 22.3%(95% CI: 20.6%; 24.1%), and 18.8%(95% CI: 16.8%; 20.9%) and 25.2%(95% CI: 24.2%; 27.7%) in men and women, respectively. The percentage of awareness treatment and control among individuals with HTN were 77.5%(95% CI: 73.3%; 81.8%), 82.2%(95% CI: 70.2%; 81.6%) and 75.9%(95% CI: 70.2%; 81.6%), respectively. The Cn for prevalence of HTN was -0.084. Two factors, age (58.46%) and wealth (32.40%), contributed most to the socioeconomic inequality in the prevalence of HTN. CONCLUSION: The prevalence of HTN was higher among low-SES individuals, who also showed higher levels of awareness. However, treatment and control of HTN were more concentrated among those who had higher levels of SES, indicating that people at a higher risk of adverse event related to HTN (the low SES individuals) are not benefiting from the advantage of treatment and control of HTN. Such a gap between diagnosis (prevalence) and control (treatment and control) of HTN needs to be addressed by public health policymakers.

Seroprevalence of SARS-CoV-2 antibody among urban Iranian population: findings from the second large population-based cross-sectional study.

BACKGROUND: The first large serosurvey in Iran found a SARS-CoV-2 antibody seroprevalence of 17.1% among the general population in the first wave of the epidemic by April, 2020. The purpose of the current study was to assess the seroprevalence of COVID-19 infection among Iranian general population after the third wave of the disease. METHODS: This population-based cross-sectional study was conducted on 7411 individuals aged ≥10 years old in 16 cities across 15 provinces in Iran between January and March, 2021. We randomly sampled individuals registered in the Iranian electronic health record system based on their national identification numbers and invited them by telephone to a healthcare center for data collection. Presence of SARS-CoV-2-specific IgG and IgM antibodies was assessed using the SARS-CoV-2 ELISA kits. The participants were also asked about their recent COVID-19-related symptoms, including cough, fever, chills, sore throat, headache, dyspnea, diarrhea, anosmia, conjunctivitis, weakness, myalgia, arthralgia, altered level of consciousness, and chest pain. The seroprevalence was estimated after adjustment for population weighting and test performance. RESULTS: The overall population-weighted seroprevalence adjusted for test performance was 34.2% (95% CI 31.0-37.3), with an estimated 7,667,874 (95% CI 6,950,412-8,362,915) infected individuals from the 16 cities. The seroprevalence varied between the cities, from the highest estimate in Tabriz (39.2% [95% CI 33.0-45.5]) to the lowest estimate in Kerman (16.0% [95% CI 10.7-21.4]). In the 16 cities studied, 50.9% of the seropositive individuals did not report a history of symptoms suggestive of COVID-19, implying an estimation of 3,902,948 (95% CI 3,537,760-4,256,724) asymptomatic infected individuals. CONCLUSIONS: Nearly one in three individuals were exposed to SARS-CoV-2 in the studied cities by March 2021. The seroprevalence increased about two-fold between April, 2020, and March, 2021.

Association of a pro-inflammatory diet with type 2 diabetes and hypertension: results from the Ravansar non-communicable diseases cohort study.

BACKGROUND: Most non-communicable diseases (NCDs) are associated to diet and inflammation. The Dietary Inflammatory Index (DII) is a developed and validated self-assessment tool. The study was conducted to assess the association of DII with the hypertension (HTN) and type 2 diabetes mellitus (T2DM). METHODS: This cross-sectional analysis was conducted on 9811 participants aged 35 to 65 years from the Ravansar Non-Communicable Diseases (RaNCD) cohort study's baseline phase data. The DII was calculated using 31 food frequency questionnaire parameters (FFQ). Univariable and multiple logistic regression was used to derive the estimates. RESULTS: In healthy participants, the mean DII score was - 2.32 ± 1.60; in participants with T2DM, HTN, or T2DM&HTN, the mean DII score was - 2.23 ± 1.59, - 2.45 ± 1.60 and - 2.25 ± 1.60, respectively (P = 0.011). Males had a significantly higher pro-inflammatory diet than females (P <  0.001). BMI (body mass index), triglyceride, energy intake, smokers were significantly higher and socio-economic status (SES), physical activity and HDL-C were significantly lower in the most pro-inflammatory diet compared to the most anti-inflammatory diet. Participants with T2DM, HTN, and T2DM&HTN had significantly higher mean anthropometry indices (P <  0.001) and lipid profiles than healthy subjects (P <  0.001). After adjusting for age, gender, and physical activity, the probability of developing T2DM was 1.48 (95% CI: 1.19, 1.85) times greater in the fourth quartile of DII than in the first quartile. CONCLUSIONS: The findings of this study showed that an anti-inflammatory diet are associated with HTN, T2DM, and the risk factors associated with these conditions. Modification of diet is recommended to reduce inflammation.

All-Cause and Cause-Specific Mortality in Middle-Aged Individuals with Positive HBsAg: Findings from a Prospective Cohort Study.

BACKGROUND: While hepatitis B virus (HBV) is the most prevalent cause of adult liver transplants in Iran, the mortality rates and leading causes of death in HBV patients are not well-understood. This study aimed to investigate all-cause and cause-specific mortality among HBsAg positive individuals in a large Iranian cohort. METHODS: The Golestan Cohort Study includes 50045 individuals aged 40-75 residing in Iran's Golestan province, enrolled during 2004-2008. HBsAg test was performed at baseline. For the present study, individuals with hepatitis C coinfection were excluded. All-cause mortality was considered as the primary outcome. The association between HBsAg and different mortality causes was evaluated using Cox proportional hazard models. P value<0.05 was considered significant. RESULTS: The current study included 49667 participants. After 11.33 (median) follow-up years, there were 7,686 total deaths, with 635 deaths in the HBsAg positive group. In the multivariate Cox proportional hazard model, HBsAg positive individuals had higher all-cause (adjusted hazard ratio [aHR]=1.15, 95% CI: 1.06-1.24) and liver-related mortality risk (aHR=7.13; 5.19-9.79). Mortality from colorectal and pancreatic cancers was higher among male HBsAg positive participants (aHRs=2.41 and 2.22, respectively). Nevertheless, cardiovascular diseases (CVDs) and extrahepatic malignancies were the leading causes of death among both HBsAg positive and negative individuals, and liver-related deaths contributed to an overall 10% of deaths in HBsAg positive patients. CONCLUSION: HBV is associated with significant mortality risk from different causes in Iranian adults. However, solely focusing on liver outcomes in Iranian HBV patients might result in overlooking non-liver events, especially CVD and extrahepatic cancers.

Prevalence, awareness, treatment, and control of hypertension based on ACC/AHA versus JNC7 guidelines in the PERSIAN cohort study.

In this cross-sectional population-based study, we used the baseline data of the Prospective Epidemiologic Research Studies in IrAN cohort study collected in Iran from 2014 to 2020. The main outcomes were the prevalence of hypertension and proportion of awareness, treatment, and control based on the 2017 ACC/AHA guideline compared to the seventh report of the Joint National Committee (JNC7). Of the total of 163,770 participants, aged 35-70 years, 55.2% were female. The sex-age standardized prevalence of hypertension was 22.3% (95% CI 20.6, 24.1) based on the JNC7 guideline and 36.5% (31.1, 41.8) based on the ACC/AHA guideline. A total of 24,312 participants [14.1% (10.1, 18.1)] were newly diagnosed based on the ACC/AHA guideline. Compared to adults diagnosed with hypertension based on the JNC7 guideline, the newly diagnosed participants were mainly young literate males who had low levels of risk factors and were free from conventional comorbidities of hypertension. About 30.7% (25.9, 35.4) of them (4.3% of the entire population) were eligible for pharmacologic intervention based on the ACC/AHA guideline. Implementation of the new guideline may impose additional burden on health systems. However, early detection and management of elevated blood pressure may reduce the ultimate burden of hypertension in Iran.

Nationwide Prevalence of Diabetes and Prediabetes and Associated Risk Factors Among Iranian Adults: Analysis of Data from PERSIAN Cohort Study.

INTRODUCTION: Over the past decades prevalence of diabetes has increased in Iran and other countries. This study aimed to update the prevalence of diabetes and prediabetes in Iran and to determine associated sociodemographic risk factors, as well as diabetes awareness and control. METHODS: This is a nationally representative cross-sectional survey that included 163,770 Iranian adults aged 35-70 years, from different ethnic backgrounds, between 2014 and 2020. Diabetes was diagnosed at fasting blood sugar of ≥ 6.99 mmol/L (126 mg/dL), or receiving blood glucose-lowering treatment. Multivariable logistic regression was applied to detect determinants associated with prevalence of diabetes and prediabetes, as well as predictors of diabetes awareness and glycemic control. RESULTS: Sex- and age-standardized prevalence of diabetes and prediabetes was 15.0% (95% CI 12.6-17.3) and 25.4% (18.6-32.1), respectively. Among patients with diabetes, 79.6% (76.2-82.9) were aware of their diabetes. Glycemic control was achieved in 41.2% (37.5-44.8) of patients who received treatment. Older age, obesity, high waist to hip ratio (WHR), and specific ethnic background were associated with a significant risk of diabetes and prediabetes. Higher awareness of diabetes was observed in older patients, married individuals, those with high WHR, and individuals with high wealth score. Moreover, glycemic control was significantly better in women, obese individuals, those with high physical activity, educational attainment, and specific ethnic background. CONCLUSIONS: The prevalence of diabetes and prediabetes is increasing at an alarming rate in Iranian adults. High proportion of uncontrolled patients require particular initiatives to be integrated in the health care system.

The Seroprevalence of COVID-19 in Intravenous Drug Users in Comparison to Non-drug Users.

BACKGROUND COVID-19 infection has led to a worldwide pandemic, and new cases are on the rise. Intravenous drug users (IVDU) are presumably at a higher risk of being infected since they have poor personal hygiene, live in groups, and have risky behaviors. The current study aimed to evaluate the seroprevalence of COVID-19 in IVDU in comparison with non-drug users (N-DU). METHODS This cross-sectional study was conducted on 167 IVDU and 134 N-DU. A questionnaire gathering data on demographics, comorbidities, and use of personal protective equipment was administered to all participants. In addition, 5 cc of blood was taken from each individual to test for SARS-CoV-2 specific antibodies (Pishtaz Teb SARS-Cov-2 ELISA kits). RESULTS The mean age of N-DU and IVDU were 38.9 ± 12.9 and 40.38 ± 10.24 years, respectively. COVID-19 seroprevalence in IVDU was 9.7%, and 4.8% in N-DU, but this finding was not statistically significant (p = 0.096). CONCLUSION While the seroprevalence of COVID-19 was not significantly different among the two groups, IVDU should still be considered by policymakers as a high-risk group due to their lifestyle and risky behaviors. Providing personal protective equipment and other means of protection and treatment to this population can help mitigate the spread of and mortality from COVID-19.

Metabolic syndrome and lifestyle-associated factors in the ethnically diverse population of Khuzestan, Iran: a cross-sectional study.

PURPOSE: Metabolic syndrome (MetS) is a cluster of risk factors, mainly central obesity, insulin resistance, and dyslipidemia, leading to life-threatening cardiovascular diseases. The prevalence of MetS can vary based on different ethnicities and many cultural and lifestyle factors. AIMS: We aimed to evaluate the prevalence of MetS and possible correlations with lifestyle-associated factors among different ethnicities in Khuzestan, Iran. METHODS: This cross-sectional study was conducted in Khuzestan province of Iran, among 30,504 participants aged 20-65 years, between October 2016 and November 2019. Data was collected through questionnaires along with anthropometric and biological measurements. The National Cholesterol Education Program Adult Treatment Panel III definition was used to estimate MetS prevalence. RESULTS: Overall, 31.9% (95% CI 31.4-32.4) had MetS (34.2% [95% CI 33.3-35.1] among males; 30.7% [95% CI 30.0-31.3] among females [p < 0.001]). Central obesity, elevated fasting blood sugar levels, and dyslipidemia were the most common abnormalities among those with MetS. The risk of MetS was estimated to increase by age, male gender, residing in urban regions, lower educational levels, lower physical activity levels, lower sleep time, and a positive family history of diabetes mellitus (p < 0.001). Individuals of the Arab and Bakhtiary ethnicities had the highest and lowest risk of MetS, respectively. CONCLUSION: MetS prevalence varied among different ethnicities. Aging and some lifestyle-associated factors such as physical activity and sleep time were related to the risk of MetS. Raising awareness about risk factors of MetS would be of great value in setting new health policies to manage the rising trend of MetS.

The Iranian Study of Opium and Cancer (IROPICAN): Rationale, Design, and Initial Findings.

BACKGROUND: The International Agency for Research on Cancer (IARC) recently classified opium use as a Group 1 carcinogen. However, much remains to be studied on the relation between opium and cancer. We designed the Iranian Opium and Cancer (IROPICAN) study to further investigate the association of opium use and cancers of the head and neck, bladder, lung, and colon and rectum. In this paper, we describe the rationale, design, and some initial results of the IROPICAN Study. METHODS: The IROPICAN is a multi-center case-control study conducted in 10 provinces of Iran. The cases were all histologically confirmed and the controls were selected from hospital visitors who were free of cancer, were not family members or friends of the cancer patients, and were visiting the hospital for reasons other than their own ailment. The questionnaires included detailed questions on opium use (including age at initiation, duration, frequency, typical amount, and route), and potential confounders, such as tobacco use (e.g., cigarettes, nass and water-pipe), and dietary factors. Biological samples, including blood and saliva, were also collected. RESULTS: The validation and pilot phases showed reasonably good validity, with sensitivities of 70% and 69% for the cases and controls, respectively, in reporting opium use. The results also showed excellent reliability, with intra-class correlation coefficients of 0.96 for ever opium use and 0.88 (95% CI: 0.80, 0.92) for regular opium use. In the main phase, we recruited 3299 cancer cases (99% response rate) and 3477 hospital visitor controls (89% response rate). The proportion of ever-use of opium was 40% among cases and 18% among controls. CONCLUSION: The IROPICAN study will serve as a major resource in studies addressing the effect of opium on risk of cancers of the head and neck, bladder, lung, and colon and rectum.

The profile of Rafsanjan Cohort Study.

Owning the largest human-made jungle of pistachio, the second largest copper mine, and being located on the trade route of opium transit, distinguish Rafsanjan from many other cities in Iran. The environmental exposures and lifestyle factors associated with these characteristics of Rafsanjan, have raised concern about possible health outcomes for individuals living in and around this city. Thus, local health authorities initiated the Rafsanjan Cohort Study (RCS), as part of the prospective epidemiological research studies in IrAN (PERSIAN). RCS is a population-based prospective cohort of men and women aged 35-70 years, launched in August 2015. Individuals from diverse socioeconomic levels and lifestyles were recruited from four urban and suburban areas of Rafsanjan (participation rate 67.42%). Questionnaire-based interviews regarding demographics, dietary and environmental exposures, medical and occupational history, as well as anthropometric measurements were completed for all participants. Additionally, bio-specimens (blood, urine, hair, and nail) were collected, and dental and eye examinations were performed. The enrollment phase ended in December 2017, and a 15-year follow-up is planned. A total of 9990 individuals were enrolled in RCS (53.41% females). About 26% of men are pistachio farmers. The baseline prevalence of major non-communicable disease (NCD) risk factors such as cigarette smoking, alcohol consumption and opium use were 25.45%, 10.02%, and 23.81%, respectively. The mean ± SD of other common risk factors are as follows: body mass index (27.83 ± 4.89 mm Hg), systolic blood pressure (107.18 ± 17.56 mm Hg) diastolic blood pressure (71.13 ± 10.83), fasting blood sugar (113.27 ± 39.11 mg/dL) and plasma cholesterol (198.78 ± 41.89 mg/dL). These results indicate a concerning prevalence of NCD risk factors in Rafsanjan city, warranting further detailed investigations, particularly regarding the association of NDC with agricultural/industrial pollutants and drug abuse.

SARS-CoV-2 antibody seroprevalence in the general population and high-risk occupational groups across 18 cities in Iran: a population-based cross-sectional study.

BACKGROUND: Rapid increases in cases of COVID-19 were observed in multiple cities in Iran towards the start of the pandemic. However, the true infection rate remains unknown. We aimed to assess the seroprevalence of antibodies against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in 18 cities of Iran as an indicator of the infection rate. METHODS: In this population-based cross-sectional study, we randomly selected and invited study participants from the general population (from lists of people registered with the Iranian electronic health record system or health-care centres) and a high-risk population of individuals likely to have close social contact with SARS-CoV-2-infected individuals through their occupation (from employee lists provided by relevant agencies or companies, such as supermarket chains) across 18 cities in 17 Iranian provinces. Participants were asked questions on their demographic characteristics, medical history, recent COVID-19-related symptoms, and COVID-19-related exposures. Iran Food and Drug Administration-approved Pishtaz Teb SARS-CoV-2 ELISA kits were used to detect SARS-CoV-2-specific IgG and IgM antibodies in blood samples from participants. Seroprevalence was estimated on the basis of ELISA test results and adjusted for population weighting (by age, sex, and city population size) and test performance (according to our independent validation of sensitivity and specificity). FINDINGS: From 9181 individuals who were initially contacted between April 17 and June 2, 2020, 243 individuals refused to provide blood samples and 36 did not provide demographic information and were excluded from the analysis. Among the 8902 individuals included in the analysis, 5372 had occupations with a high risk of exposure to SARS-CoV-2 and 3530 were recruited from the general population. The overall population weight-adjusted and test performance-adjusted prevalence of antibody seropositivity in the general population was 17·1% (95% CI 14·6-19·5), implying that 4 265 542 (95% CI 3 659 043-4 887 078) individuals from the 18 cities included were infected by the end of April, 2020. The adjusted seroprevalence of SARS-CoV-2-specific antibodies varied greatly by city, with the highest estimates found in Rasht (72·6% [53·9-92·8]) and Qom (58·5% [37·2-83·9]). The overall population weight-adjusted and test performance-adjusted seroprevalence in the high-risk population was 20·0% (18·5-21·7) and showed little variation between the occupations included. INTERPRETATIONS: Seroprevalence is likely to be much higher than the reported prevalence of COVID-19 based on confirmed COVID-19 cases in Iran. Despite high seroprevalence in a few cities, a large proportion of the population is still uninfected. The potential shortcomings of current public health policies should therefore be identified to prevent future epidemic waves in Iran. FUNDING: Iranian Ministry of Health and Medical Education. TRANSLATION: For the Farsi translation of the abstract see Supplementary Materials section.

The Khuzestan Comprehensive Health Study (KCHS): Methodology and Profile of Participants.

BACKGROUND: Non-communicable diseases (NCDs) are the leading cause of death worldwide, with a disproportionally rising burden among low- and middle-income populations. While preventable risk factors highly contribute to this burden, population-based studies assessing these factors and the health status of these populations, are scarce. METHODS: The Khuzestan Comprehensive Health Study (KCHS)-a cross sectional study-was conducted between 2016-2019, including 30,506 Iranians aged 20 to 65 years, from 27 counties of Khuzestan province, southwest of Iran. KCHS aimed to provide a comprehensive health overview by investigating the prevalence and risk factors of NCDs and psychological disorders, along with viral hepatitis as a common communicable disease. Upon registration, 15 mL of blood and anthropometric measurements were obtained from participants. Afterwards, several interviewer-administered questionnaires were completed to gather data on demographics, socioeconomic status, sleep quality, physical activity, lifestyle habits, nutrition, and medical history. RESULTS: The mean ± SD age of participants was 41.7 ± 11.9 years. The majority were female (64.3%), of the Arab ethnicity (49%), married (83%), and urban residents (73.1%). About 70% had an educational level below high school diploma. Overall, 10.8%, 5.2%, and 2.8% of participants had used cigarettes, hookah, and drugs at least once in their lifetime, respectively. While body mass index and serum cholesterol levels were higher in females, blood pressure was higher in males (P<0.001). CONCLUSION: KCHS assessed many aspects of health in the Khuzestan province. In addition to develop a biobank along with a comprehensive dataset, KCHS will serve as a valuable infrastructure for future research.