Bibliometric overview of the Tehran Lipid and Glucose Study (TLGS) publications from 2000 to 2022.

Aim: The present study was conducted to analyze the publications of the Tehran Lipid and Glucose Study (TLGS) and assess its scientific productions during the last 23 years. Methods: The required data were retrieved from the Scopus database. The advanced search was chosen, and the search query included terms related to the TLGS. Search and retrieval of data were conducted on August 30, 2022. Bibliometric indicators have been used at three levels in this research including the level of documents, journals, and authors. Also, the knowledge structure of this set was analyzed at the level of social structure and the level of conceptual structure. Data analysis and visualizations was performed using Bibliometrix and VOSviewer software. Results: A total of 870 documents related to the TLGS have been indexed in the Scopus from 2000 to 2022, and 1148 authors have participated in the relevant studies. 66.4% of the TLGS documents were published in journals with Q1 subject area quartiles. There was an annual growth rate of 20% and average citations per document of 16.5. There was a co-authorship per document of 5.6 and an international co-authorship of 8.7%. According to the co-occurrence network for keywords, the most common areas in the TLGS published documents were nutrition, epidemiologic issues, cardiometabolic-related biomarkers, diabetes, hypertension, lifestyle variables and genetic studies. Conclusion: Over the past 23 years, the TLGS has successfully addressed a wide range of inquiries pertaining to cardiometabolic and nutritional issues in Iran. The remarkable achievements of the TLGS act as a catalyst, advocating for the planning and implementation of additional cohort studies that specifically focus on non-communicable diseases within the Iranian population.

Adiposity trajectories and cardiovascular disease risk in women: a population-based cohort study with a focus on menopausal status.

Objectives: A single measurement of adiposity indices could predict the incidence of cardiovascular disease (CVD); nonetheless their long-term pattern and its association with incident CVD are rarely studied. This study aimed to determine distinct trajectories of adiposity indices among participants of Tehran Lipid and Glucose Study (TLGS) and their association with incident CVD. Furthermore, this study aimed to investigate whether this association differed among individuals according to their menopausal status. Method: A total of 6840 women participated in TLGS, aged 20 years and older were included in this study; they were followed for a median of 16 years. Body mass index (BMI), waist circumference (WC), conicity index (CI) and body roundness index (BRI) were included in the analysis as adiposity indices. The cohort outcome panel of medical specialists identified the CVD outcomes. Trajectory analyses were used to identify homogeneous distinct clusters of adiposity indices trajectories. The association between the trajectory group membership and incident CVD were explored by Cox proportional hazard models, with unadjusted and adjusted model for baseline age, physical activity, smoking status, menopause and family history of CVD. Results: Three BMI trajectory groups of low, medium, and high and two trajectories for WC, BRI and CI were identified. Adjusted cox proportional hazard models revealed significant associations between the hazard of CVD experience and the high trajectory group of the BMI (HR: 2.06, 95% CI: 1.38-3.07), WC (HR: 2.71, 95% CI: 1.98-3.70), CI (HR: 1.87, 95% CI: 1.26-2.77) and BRI (HR: 1.55-95% CI: 1.12-2.15), compared to the low trajectory group. Subgroup analysis based on the menopausal status of participants showed that the HR of CVD incidences for all of trajectories adiposity indices, except BMI, was statistically significant. Adjusted cox proportional hazard models, in those women not reached menopause during study, revealed that the HR (95% CI) of CVD incidences for high trajectory of BMI, WC, CI and BRI were 2.80 (1.86-7.05); 2.09 (1.40-6.16); 1.72 (1.42-5.61), and 3.09 (1.06-9.01), respectively. These values for those were menopause at the initiation of the study were 1.40 (1.11, 2.53); 1.65 (1.04-2.75); 1.69 (1.01-2.87), and 1.61 (0.98-2.65), respectively. Conclusion: Our findings suggest that adiposity trajectories, particularly central adiposity index of CI, could precisely predict the CVD risk. Consequently, preventive strategies should be tailored accordingly.

Preconceptional maternal hyperandrogenism and metabolic syndrome risk in male offspring: a long-term population-based study.

PURPOSE: There is limited research on the effects of maternal hyperandrogenism (MHA) on cardiometabolic risk factors in male offspring. We aimed to compare the risk of metabolic syndrome (MetS) in sons of women with preconceptional hyperandrogenism (HA) to those of non-HA women in later life. METHODS: Using data obtained from the Tehran Lipid and Glucose Cohort Study, with an average of 20 years follow-up, 1913 sons were divided into two groups based on their MHA status, sons with MHA (n = 523) and sons without MHA (controls n = 1390). The study groups were monitored from the baseline until either the incidence of events, censoring, or the end of the study period, depending on which occurred first. Age-scaled unadjusted and adjusted Cox regression models were utilized to evaluate the hazard ratios (HRs) and 95% confidence intervals (CIs) for the association between MHA and MetS in their sons. RESULTS: There was no significant association between MHA and HR of MetS in sons with MHA compared to controls, even after adjustment (unadjusted HR (95% CI) 0.94 (0.80-1.11), P = 0.5) and (adjusted HR (95% CI) 0.98 (0.81-1.18), P = 0.8). Sons with MHA showed a HR of 1.35 for developing high fasting blood sugar compared to controls (unadjusted HR (95% CI) 1.35 (1.01-1.81), P = 0.04), however, after adjustment this association did not remain significant (adjusted HR (95% CI) 1.25 (0.90-1.74), P = 0.1). CONCLUSION: The results suggest that preconceptional MHA doesn't increase the risk of developing MetS in sons in later life. According to this suggestion, preconceptional MHA may not have long-term metabolic consequences in male offspring.

Factors associated with smoking intensity among adult smokers: findings from the longitudinal cohort of the Tehran lipid and glucose study.

BACKGROUND: Smoking is a significant public health problem, and there is a scarcity of documents regarding its severity, particularly in developing countries. This study aimed to determine factors related to the number of cigarettes consumed daily by adult smokers in Tehran. METHODS: This study was conducted within the framework of the longitudinal study of Tehran Lipid and Glucose Study (TLGS). The study included 786 adult smokers living during four consecutive follow-ups from 2005 to 2016. The intensity of smoking was measured by the number of cigarettes consumed daily by adult smokers. Data analysis was done longitudinally and based on the mixed effects zero-inflated discrete Weibull (ZIDW) regression model. RESULTS: The mean age of the individuals was 40.35 ± 12.68 years, and 643 (81.8%) of them were men. Also, 52.7% of individuals were daily smokers, 15.6% were occasional smokers, and 31.7% were non-smokers who became smokers during the study. Variables of age 1.005 (95%CI: 1.001-1.008), gender of male 1.196 (95%CI: 1.051-1.39), and marital status (divorced/widowed vs. single) 1.168 (95%CI: 1.015-1.39) were positively associated with smoking intensity. Education level (master and higher vs. illiterate) 0.675 (95%CI: 0.492-0.926)), employment status (student vs. unemployed) 0.683 (95%CI: 0.522-0.917), (housewife vs. unemployed) 0.742 (95%CI: 0.606-0.895), (Unemployed with income vs. unemployed) 0.804 (95%CI: 0.697, 0.923), implementation of smoking prohibition regulations (yes vs. no) 0.88 (95%CI: 0.843-0.932), and history of cardiovascular disease in male relatives (yes vs. no) 0.85 (95%CI: 0.771-0.951) were associated with lower smoking intensity. CONCLUSION: We showed that demographic factors are associated with the intensity of smoking among adults and should be considered in policymakers' intervention programs to reduce smoking and quit smoking.

Association of baseline and changes in adiponectin, homocysteine, high-sensitivity C-reactive protein, interleukin-6, and interleukin-10 levels and metabolic syndrome incidence: Tehran lipid and glucose study.

Background: Metabolic syndrome (MetS) is accompanied by chronic low-grade inflammation, and inflammatory markers like high-sensitivity C-reactive protein(hs-CRP), interleukin-6(IL-6), and homocysteine(Hcy) contribute to inflammation, obesity, and insulin resistance. Adiponectin(AdipoQ) and interleukin-10(IL-10) are anti-inflammatory markers that play protective roles in MetS. This study aimed to investigate the association between these biochemical marker changes and MetS in a sample of the Tehranian population during six years of follow-up. Methods: In this longitudinal study, 340 adults at baseline and after a six-year follow-up, aged ≥18 years, were selected randomly from the Tehran Lipid and Glucose Study (TLGS). MetS was defined according to the Joint Interim Statement (JIS) criteria. Individuals were categorized into four groups based on their MetS status at baseline and follow-up: 1) non-MetS: participants who did not have MetS at both baseline and follow-up; 2) incident MetS: participants who did not have MetS at baseline but developed MetS during the follow-up ; 3) recovery MetS: participants who had MetS at baseline but no longer had MetS during the follow-up; 4) persistent MetS: participants who had MetS both at baseline and follow-up. Results: The mean follow-up time was 6.1 years. There were 176 subjects in the non-MetS group, 35 in the incident MetS group, 41 in the recovery MetS group, and 88 in the persistent MetS group. Increases in the levels of both hs-CRP 1.40 (95% CI: 1.15, 1.71, p = 0.001) and IL-6 1.09 (95% CI: 1.03, 1.17, p = 0.004) significantly increased the odds of the incident and persistent MetS, respectively. The area under the ROC curve (AUC) was more than 0.69 (p < 0.000) for hs-CRP in predicting MetS incidence and more than 0.86 (p < 0.000) for IL-6 in predicting MetS persistence. Conclusion: After a six-year average follow-up, hs-CRP and IL-6 levels were deemed more reliable predictors of MetS incidence and persistence, respectively.

The Hidden Link between Polycystic Ovary Syndrome and Kidney Stones: Finding from the Tehran Lipid and Glucose Study (TLGS).

BACKGROUND: We aimed to investigate the association between kidney stones and polycystic ovarian syndrome (PCOS). MATERIALS AND METHODS: In a cross-sectional study, data from the Tehran Lipid and Glucose Study (TLGS) were used to investigate the risk of kidney stones in women with Polycystic Ovary Syndrome (PCOS). Four distinct phenotypes of PCOS, as defined by the Rotterdam criteria, were examined in a sample of 520 women and compared to a control group of 1638 eumenorrheic non-hirsute healthy women. Univariate and multivariable logistic regression models were employed for analysis. The four PCOS phenotypes were classified as follows: Phenotype A, characterized by the presence of all three PCOS features (anovulation (OA), hyperandrogenism (HA), and polycystic ovarian morphology on ultrasound (PCOM)); Phenotype B, characterized by the presence of anovulation and hyperandrogenism; Phenotype C, characterized by the presence of hyperandrogenism and polycystic ovarian morphology on ultrasound; and Phenotype D, characterized by the presence of anovulation and polycystic ovarian morphology on ultrasound. RESULTS: The prevalence of a history of kidney stones was found to be significantly higher in women with Polycystic Ovary Syndrome (PCOS) compared to healthy controls (12.5% vs. 7.7%, p = 0.001). This increased prevalence was observed across all PCOS phenotypes (p < 0.001). After adjusting for potential risk factors, including age, family history of kidney stones, waist-to-height ratio, total cholesterol, and low-density lipoprotein, the odds ratio for kidney stones in women with PCOS was found to be 1.59 [95% CI: 1.12-2.25, p = 0.01], indicating a 59% increase in risk compared to healthy women. Women with PCOS Phenotype A [OR: 1.97, 95% CI: 1.09-3.55, p = 0.02] and Phenotype D [OR: 3.03, 95% CI: 1.24-7.41, p = 0.01] were found to be at a higher risk for kidney stones. CONCLUSION: Women with Polycystic Ovary Syndrome (PCOS), particularly those exhibiting menstrual irregularities and polycystic ovarian morphology on ultrasound (PCOM), have been found to be two to three times more likely to develop kidney stones. This increased prevalence should be taken into consideration when providing preventive care and counseling to these individuals.

Idiopathic Hirsutism and Metabolic Status: A Population-based Prospective Cohort Study.

BACKGROUND: A limited number of studies have investigated the impact of idiopathic hirsutism (IH) on cardiometabolic parameters with contradictory and inconclusive results. This study aimed to explore the effect of IH on metabolic outcomes. METHOD: In this population-based prospective study, 334 women with IH and 1226 women as healthy controls were selected from Tehran Lipid and Glucose Study. The generalized estimation equations method was applied to investigate the secular longitudinal trends of metabolic indices, including fasting blood sugar (FBS), high-density lipoprotein cholesterol (HDL-C), low-density lipoprotein cholesterol (LDL), non-HDL, triglyceride (TG), systolic blood pressure (SBP), diastolic blood pressure (DBP), and waist circumference (WC) in both groups. Unadjusted and adjusted Cox regression models were applied to assess the hazard ratios (HR) and 95% CIs for the association between IH and metabolic disorders. Potential confounding factors such as age, body mass index, smoking, physical activity, history of hypertension (HTN), and family history of diabetes were included in the adjusted model. RESULTS: This study showed that compared with healthy controls, women with IH had lower SHBG and higher total testosterone (median [interquartile ratio; IQR]: 0.37 [0.16-0.70] vs 0.33 [0.14-0.58]; P = 0.01), free androgen index (median [IQR]: 0.85 [0.38-1.54] vs 0.54 [0.26-0.97]; P = 0.001), androstenedione (median [IQR]: 1.60 [1.00-2.25] vs 1.10 [0.90-1.70]; P = 0.001), and dehydroepiandrosterone sulfate (median [IQR]: 168.5 [91.1-227.8] vs 125.2 [66.3-181]; P = 0.001). Over time, mean changes of FBS, HDL-C, LDL-C, non-HDL-C, TG, SBP, DBP, and WC were not significantly different in women with IH, compared with healthy controls. According to the unadjusted Cox regression model, except for type 2 diabetes mellitus (T2DM) (HR [95% CI]: 1.45 [1.00-2.11]) P = 0.05; there was no statistically significant difference in hazard of metabolic disorders (ie, HTN, pre-HTN, pre-T2DM, and metabolic syndrome) in IH, compared with healthy controls. Besides, the adjusted Cox regression model showed no significant differences in the hazard of these outcomes. CONCLUSION: This study showed no significant difference in overtime mean changes of metabolic risk factors and cardiometabolic outcomes in women with IH, compared with the healthy control group, except marginally significant difference on T2DM, which disappeared after further adjustment for potential confounders. Accordingly, routine screening of women for these metabolic outcomes should not recommend.

Parental Transmission Plays the Major Role in High Aggregation of Type 2 Diabetes in Iranian Families: Tehran Lipid and Glucose Study.

BACKGROUND: This study is the first to evaluate familial aggregation, heritability and inheritance mode of type 2 diabetes (T2D) in Tehran Lipid Glucose Study (TLGS) participants as a representative sample of the Iranian population. METHODS: From the ongoing family-based TLGS cohort, 13,741 individuals at least 20 years of age (mean ± standard deviation, 39.71±16.56) were assessed. After correcting family structures using genomic information from the Tehran Cardiometabolic Genetic Study, 2,594 constituent pedigrees were constructed. Familial aggregation was assessed based on genealogic index testing, familial intraclass correlation and positive family history. Family-based heritability was checked with 2 linear mixed models, including 2 different random components: the kinship matrix and the genomic relationship matrix. The mode of inheritance of T2D was investigated by complex segregation analysis (CSA). RESULTS: Familial aggregation of T2D was significant (p<0.05), and family-based heritability showed a high degree of genetic variation in T2D between individuals at 65% (standard error, 0.034). Within first-degree relatives (parent/offspring and siblings), the likelihood of a parental affect was higher than in siblings (odds ratio, 4.11 vs 1.65). Family history of T2D among first-degree relatives was more noteworthy than for second-degree relatives (odds ratio, 3.84 vs 0.59). CSA revealed that the polygenic model is best to illustrate the mode of inheritance of T2D for TLGS participants. CONCLUSIONS: Our findings demonstrate that the heritability of T2D with polygenic mode in the Iranian population is higher than the global average. We also found that T2D is transmitted equally into siblings, with parental affect the leading risk factor. These data suggest that policymakers should change individual-level to family-level prevention.

Predisposing factors of long-term responsiveness in a cardio-metabolic cohort: Tehran Lipid and Glucose Study.

BACKGROUND: Non-participation in cohort studies, if associated with both the exposure and occurrence of the event, can introduce bias in the estimates of interest. This study aims to identify factors associated with follow-up participation in Tehran Lipid and Glucose Study, a large-scale community-based prospective study in West Asia. METHODS: A sample of 10,368 adults from TLGS was included in the analysis. All analyses were split according to sex and age groups (20-39, 40-59, and 60 years). The associations between socio-demographic, health, and lifestyle factors with response rate were identified using the Generalized Estimating Equations model. RESULTS: Over the median of 15.7 years of follow up the response rate was 64.5%. The highest response rate was observed in those aged 40-59 years for both sexes. Current smokers had lower odds of response in both sexes for all age groups, ranging from 0.51 to 0.74, p < 0.01. In young adults, being single (OR = 0.79, OR = 0.57, p ≤ 0.01, respectively for men and women) and unemployed (OR = 0.73, OR = 0.76, p ≤ 0.01, respectively for men and women) in both sexes, high physical activity in men (OR = 0.77, p < 0.01), high education (OR = 0.75, p = 0.02) and obesity (OR = 0.85, p = 0.05) in women were associated with lower response rate. For the middle-aged group, diabetes in men (OR = 0.77, p = 0.05) and hypertension (OR = 0.84, p = 0.05), and having a history of cancer (OR = 0.43, p = 0.03) in women were factors associated with lower response rates. Finally, interventions for both sexes (OR = 0.75, OR = 0.77, p ≤ 0.05, respectively for men and women) and being divorced/widow in women (OR = 0.77, p = 0.05) were the factors associated with the lower response rate in the elderly. CONCLUSIONS: Long-term participation was influenced by socio-demographic, health, and lifestyle factors in different sex- and age-specific patterns in TLGS. Recruitment strategies targeting these factors may improve participant follow-up in longitudinal studies.

Risk of chronic kidney disease in women with a history of preterm delivery: Tehran Lipid and Glucose Study.

BACKGROUND: Preterm delivery (PTD) may predict the risk of long-term maternal complications. Little is known about the association between preterm delivery and maternal risk of chronic kidney disease (CKD).This study aimed to explore whether a history of preterm delivery is associated with the risk of maternal CKD. METHODS: In this population-based cohort study within the framework of the Tehran Lipid and Glucose Study (TLGS), a total of 3035 women with at least one delivery met our eligibility criteria. A time-dependent Cox proportional-hazards regression model was used to measure the hazard ratios (HRs) and 95% confidence intervals (CIs) for evaluating the association between history of preterm delivery and risk of CKD, adjusted for smoking, parity, age at first delivery, body mass index, educational level, preeclampsia, and gestational diabetes mellitus. RESULTS: A total of 212 women with a history of at least one preterm delivery and 2823 women with term delivery were included. The median (interquartile range) follow-up in the preterm and term delivery groups was 16 (13.0-17.0) and 16 (14.0-17.0) years, respectively. The results of multivariate Cox regression model, adjusted for confounders, showed that the risk of CKD significantly increased by 46% in women with a history of preterm delivery. Moreover, according to the time-dependent Cox regression analysis, the risk of CKD in women with a history of preterm delivery was 2.68 (95% CI 1.02, 7.05, P = 0.04) fold higher than among those with no history of  preterm delivery. CONCLUSION: Pregnancy if complicated by preterm delivery, may increase the risk of future maternal morbidities. Our findings suggest that a history of preterm delivery was associated with an increased maternal risk of CKD in the long term. Further longitudinal studies are needed to confirm our findings.

Trends in dietary food groups and Dietary Approach to Stop Hypertension (DASH) score among adults: A longitudinal study from the Tehran Lipid and Glucose Study, 2006-2017.

OBJECTIVES: This study aimed to examine the secular trends of dietary food groups and diet quality among adults, overall and by sex, education, and employment status. METHODS: This study was conducted within the framework of the Tehran Lipid and Glucose Study. Demographic and anthropometric measurements were gathered using standard questionnaires. In terms of socioeconomic information, participants were divided into two groups according to their educational level and employment status. The regular dietary intakes of participants were gathered with a validated and reliable food frequency questionnaire over the previous year, and Dietary Approaches to Stop Hypertension scores were computed to evaluate diet quality. Generalized estimating equations were used to assess secular trends in food groups within the four phases. RESULTS: From 2006 to 2017, intake of whole grains, legumes, and nuts and seeds increased, and intake of refined grains, dairy products, and solid fats decreased significantly (P for trend < 0.001). Dietary fruit, vegetable, meat, and soft drink intake did not change significantly. According to socioeconomic groups, meat intake decreased significantly among men, uneducated, and unemployed participants, and fruit intake increased in both women and educated participants. Based on a 40-point scale, the Dietary Approaches to Stop Hypertension score increased from 18.1 ± 0.0 in phase1 to 22.7 ± 0.1 in phase 4 of the Tehran Lipid and Glucose Study (P for trend < 0.001). CONCLUSIONS: Over a decade, in addition to improvements in intake of a number of dietary food groups, the estimated overall diet quality of the study population showed a modest improvement. These findings may determine areas for more attention to improve the overall dietary intake of the population.

The dynamics of metabolic syndrome development from its isolated components among Iranian adults: findings from 17 years of the Tehran lipid and glucose study (TLGS).

BACKGROUND: Evaluating the process of changes in the Metabolic Syndrome (MetS) components over time is one of the ways to study of the MetS natural history. This study aimed to determine the trend of changes in the progression of MetS from its isolated components. METHODS: This longitudinal study was performed on four follow-up periods of the Tehran Lipid and Glucose Study (TLGS) between 1999 and 2015. The research population consisted of 3905 adults over the age of 18 years. MetS was diagnosed based on the Joint Interim Statement (JIS). The considered components were abdominal obesity, hypertension, hyperglycemia, and dyslipidemia. RESULTS: The highest incidence of MetS from its components was related to hypertension in the short term (3.6-year intervals). In the long run, however, the highest increase in the MetS incidence occurred due to abdominal obesity. Overall, the incidence of MetS increased due to obesity and dyslipidemia, but decreased due to the other factors. Nonetheless, the trend of MetS incidence from all components increased in total. The most common components were dyslipidemia with a decreasing trend and obesity with an increasing trend during the study. CONCLUSION: The results indicated that obesity and hypertension components played a more important role in the further development of MetS compared to other components in the Iranian adult population. This necessitates careful and serious attention in preventive and control planning.

Impact of short- and long-term exposure to air pollution on blood pressure: A two-decade population-based study in Tehran.

Plenty of recent studies on the impact of air pollution on blood pressure (BP) exist; however, there is a lack of data for the highly polluted Eastern Mediterranean region. We evaluated the associations of short-term exposure to air pollutants with systolic BP (SBP) and diastolic BP (DBP) and the long-term impact of air pollutants on incident hypertension, among Tehranian adults. In the Tehran Lipid and Glucose Study, 4580 nonhypertensive participants aged 20-69 years (41.6% male) were followed from 2001 to 2018 through 3-year follow-ups and 4-5 examinations of them were recorded. The air pollutants included particulate matter with a diameter ≤10 µm (PM10), carbon monoxide (CO), ozone (O3), nitrogen dioxide (NO2), and sulfur dioxide (SO2). The mixed-effects transition model estimated the air pollution impact on BP. The proportional hazards Weibull model measured the long-term effects of air pollutants on the multivariate hazard of incident hypertension. The air pollutants were put in the models in the form of mean annual level, applying three versions of 1, 2, and 3 years before the follow-ups. During a median follow-up of 12.3 years, 1618 cases of hypertension were found. In the short-term, increase in CO did not affect SBP but decreased DBP with a delay effect lasting for 14 days; increase in NO2 raised SBP with a 14-day lag, however did not change DBP; increase in O3 reduced SBP with a 14-day lag but made slight non-significant increase in DBP; rise in PM10 concentrations led to increased SBP (lag 0-3 days) and DBP with lags of 0-3 days and 12-14 days and increase in SO2 made the largest increases in DBP with lags lasting for 14 days, but did not affect SBP. Regarding incident hypertension in the long-term, the increase in CO had no significant effect; increase in NO2 decreased the risk over the 2- and 3-year time spans; rise in O3, PM10, and SO2 levels increased the risk in all time spans; the largest hazard ratio [1.96 (95% CI: 1.48, 2.62)] for incident hypertension was attributable to PM10 in 3 years. Considering the major effects of air pollutants including O3, SO2, and especially PM10 on incident hypertension, urgent public health policies should be implemented to reduce the burden of air pollution in metropolitan city of Tehran.

Dietary intakes of total polyphenol and its subclasses in association with the incidence of chronic kidney diseases: a prospective population-based cohort study.

BACKGROUND: As chronic kidney disease (CKD) is amongst the current global health challenges, this study is aiming to evaluate the long-term intake of total polyphenol and its subclasses in association with CKD incidence. METHODS: For the purpose of this study, a sample of 3021 Iranian adults (47 % men, aged 20-79 years) with no CKD diagnosis at baseline, were selected from the Tehran Lipid and Glucose Study population. The total intake of polyphenol and its major subclasses were assessed by a validated food frequency questionnaire and categorized as flavonoids, phenolic acids, stilbenes, and lignans. Although the morphological abnormalities of the kidneys or 3-month persistent urinalysis can distinctively define CKD, the glomerular filtration rate (eGFR) reduction is accepted as a more precise index of renal function. Therefore, eGFR < 60 mL/min/1.73m2 was the exclusive index of CKD diagnosis in the current study. The eGFR was calculated by the Modification of Diet in Renal Disease Study equation. Cox-regression analysis was used to assess the hazard ratio and 95 % confidence intervals of CKD in quartiles of the total polyphenols. RESULTS: In this study, 355 CKD cases over 11,058.464 person-years was reported. The median (IQR) age of participants was 36 years (27-46) at baseline. Moderate intake of lignans (≤ 6.8 mg) was negatively associated with the incidence of CKD in the adjusted model. No significant associations were detected between higher amounts of lignin and total polyphenols (HR: 0.97, 95 % CI 0.67-1.40) and CKD incidence. CONCLUSIONS: Based on the current findings, moderate intake of lignin possess CKD-protective properties by approximately 32 %. No independent associations were observed between higher amounts of lignins and CKD incidence.

Serum metabolomics study of women with different annual decline rates of anti-Müllerian hormone: an untargeted gas chromatography-mass spectrometry-based study.

STUDY QUESTION: Which metabolites are associated with varying rates of ovarian aging, measured as annual decline rates of anti-Müllerian hormone (AMH) concentrations? SUMMARY ANSWER: Higher serum concentrations of metabolites of phosphate, N-acetyl-d-glucosamine, branched chained amino acids (BCAAs), proline, urea and pyroglutamic acid were associated with higher odds of fast annual decline rate of AMH. WHAT IS KNOWN ALREADY: Age-related rate of ovarian follicular loss varies among women, and the factors underlying such inter-individual variations are mainly unknown. The rate of ovarian aging is clinically important due to its effects on both reproduction and health of women. Metabolomics, a global investigation of metabolites in biological samples, provides an opportunity to study metabolites or metabolic pathways in relation to a physiological/pathophysiological condition. To date, no metabolomics study has been conducted regarding the differences in the rates of ovarian follicular loss. STUDY DESIGN, SIZE, DURATION: This prospective study was conducted on 186 reproductive-aged women with regular menstrual cycles and history of natural fertility, randomly selected using random case selection option in SPSS from the Tehran Lipid and Glucose Study. PARTICIPANTS/MATERIALS, SETTING, METHODS: AMH concentrations were measured at baseline (1999-2001) and the fifth follow-up examination (2014-2017), after a median follow-up of 16 years, by immunoassay using Gen II kit. The annual decline rate of AMH was calculated by dividing the AMH decline rate by the follow-up duration (percent/year). The women were categorized based on the tertiles of the annual decline rates. Untargeted metabolomics analysis of the fasting-serum samples collected during the second follow-up examination cycle (2005-2008) was performed using gas chromatography-mass spectrometry. A combination of univariate and multivariate approaches was used to investigate the associations between metabolites and the annual decline rates of AMH. MAIN RESULTS AND THE ROLE OF CHANCE: After adjusting the baseline values of age, AMH and BMI, 29 metabolites were positively correlated with the annual AMH decline rates. The comparisons among the tertiles of the annual decline rate of AMH revealed an increase in the relative abundance of 15 metabolites in the women with a fast decline (tertile 3), compared to those with a slow decline (tertile 1). There was no distinct separation between women with slow and fast decline rates while considering 41 metabolites simultaneously using the principal component analysis and the partial least-squares discriminant analysis models. The odds of fast AMH decline was increased with higher serum metabolites of phosphate, N-acetyl-d-glucosamine, BCAAs, proline, urea and pyroglutamic acid. Amino sugar and nucleotide sugar metabolism, BCAAs metabolism and aminoacyl tRNA biosynthesis were among the most significant pathways associated with the fast decline rate of AMH. LIMITATIONS, REASONS FOR CAUTION: Estimating the annual decline rates of AMH using the only two measures of AMH is the main limitation of the study which assumes a linear fixed reduction in AMH during the study. Since using the two-time points did not account for the variability in the decline rate of AMH, the annual decline rates estimated in this study may not accurately show the trend of the reduction in AMH. In addition, despite the longitudinal nature of the study and statistical adjustment of the participants' ages, it is difficult to distinguish the AMH-related metabolites observed in this study can accelerate ovarian aging or they are reflections of different rates of the aging process. WIDER IMPLICATIONS OF THE FINDINGS: Some metabolite features related to the decline rates of AMH have been suggested in this study; further prospective studies with multiple measurements of AMH are needed to confirm the findings of this study and to better understand the molecular process underlying variations in ovarian aging. STUDY FUNDING/COMPETING INTEREST(S): This study, as a part of PhD thesis of Ms Nazanin Moslehi, was supported by Shahid Beheshti University of Medical Sciences (10522-4). There were no competing interests. TRIAL REGISTRATION NUMBER: N/A.

The dynamics of metabolic syndrome development from its isolated components among iranian children and adolescents: Findings from 17 Years of the Tehran Lipid and Glucose Study (TLGS).

BACKGROUND: Careful evaluation of the progression trend of the metabolic syndrome (MetS) in children and adolescents (C&A) is one of the important methods of studying the natural history of MetS in them. This study was performed to determine the trend of changes in the progression of MetS from its components. METHODS: This was a longitudinal study which was performed on data from 4 follow-up periods of Tehran Lipid and Glucose Study (TLGS) between 1999 and 2015. The research population consisted of 6-18-year-old children and adolescents creating 3895-person population. The criteria for the diagnosis of MetS was joint interim statement (JIS). The considered components were central adiposity, high blood pressure, insulin resistance, and dyslipidemia. RESULTS: In this study, in the long term, the highest increase in the MetS' incidence in boys occurred in obesity and in girls in dyslipidemia and in total mode, in obesity. But in the short term (3.6 year follow-up periods) in the first to fourth periods, in total mode, the highest incidence occurred in dyslipidemia, hyperglycemia, dyslipidemia, and obesity. In terms of trend, in total mode, the highest increase in MetS incidence was related to the obesity component. Also, the incidence of MetS from all components was declining in overall mode. Also, the most common components at the beginning and end of the study in all groups were dyslipidemia with a decreasing and obesity with an increasing trend, respectively. CONCLUSION: It seems that in Iranian C&As, obesity and dyslipidemia components play a more important role in the further development of the MetS than other components. This matter requires careful and serious attention in preventive and control planning.

Secular trend in dietary patterns of Iranian adults from 2006 to 2017: Tehran lipid and glucose study.

BACKGROUND: Based on data regarding nutrition transition in the Middle East and North Africa, this study aim to investigate the general structure and secular trend of dietary patterns reported from the Tehran Lipid and Glucose Study (TLGS) and adherence to these dietary patterns among Iranian population from 2006 till 2017. METHODS: We investigated on four examination waves of TLGS, including wave 1 (2006-2008), wave 2 (2009-2011), wave 3 (2012-2014), and wave 4 (2015-2017), using a validated and reliable food frequency questionnaire. Generalized Estimating Equations was used to assess secular trends in anthropometric, biochemical, and dietary variables across the study period. To identify general structure and secular trend of dietary patterns during each waves, principle component analysis (PCA) and K-mean cluster analysis were used, respectively. RESULTS: After adjusting for potential confounders including age, sex, body mass index, and total energy intake, the carbohydrate and protein intake gradually increased and the total fat intake decreased during study period (P-value< 0.001), although total energy intake remained stable. During the study period, participants consumed noticeably less refined grains, solid fat, dairy products, and simple sugars. Snack and dessert consumption increased and meat intakes showed no significant changes during a decade (all P-values< 0.001). Three dietary patterns extracted using PCA, included: Healthy dietary pattern characterized by higher intakes of vegetable, fruit, dairy products, liquid oil, nuts and seeds, and honey and jam; Western dietary pattern featured by refined grain, solid fat, meat, snack and dessert, potato, and soft drink, and the Mixed dietary pattern, highlighted by tea and coffee, and simple sugar. Based on cluster analysis, 27.8% of participants in wave 4 followed a Western dietary pattern, and 34.1% followed the Mixed dietary pattern. The Healthy dietary pattern was stable among the study population during the last decade. CONCLUSIONS: The structure and the type of foods that participants preferred to eat changed since 2006, a new secular trend in dietary patterns, including a stability of Healthy dietary pattern, a decline of the Western dietary pattern and an increase in the Mixed dietary pattern was obsereved in our investigation.

Improving Prediction of Age at Menopause Using Multiple Anti-Müllerian Hormone Measurements: the Tehran Lipid-Glucose Study.

CONTEXT: Several statistical models were introduced for the prediction of age at menopause using a single measurement of anti-müllerian hormone (AMH); however, individual prediction is challenging and needs to be improved. OBJECTIVE: The objective of this study was to determine whether multiple AMH measurements can improve the prediction of age at menopause. DESIGN: All eligible reproductive-age women (n = 959) were selected from the Tehran Lipid and Glucose Study. The serum concentration of AMH was measured at the time of recruitment and twice after that at an average of 6-year intervals. An accelerated failure-time model with Weibull distribution was used to predict age at menopause, using a single AMH value vs a model that included the annual AMH decline rate. The adequacy of these models was assessed using C statistics. RESULTS: The median follow-up period was 14 years, and 529 women reached menopause. Adding the annual decline rate to the model that included single AMH improved the model's discrimination adequacy from 70% (95% CI: 67% to 71%) to 78% (95% CI: 75% to 80%) in terms of C statistics. The median of differences between actual and predicted age at menopause for the first model was -0.48 years and decreased to -0.21 in the model that included the decline rate. The predicted age at menopause for women with the same amount of age-specific AMH but an annual AMH decline rate of 95 percentiles was about one decade lower than in those with a decline rate of 5 percentiles. CONCLUSION: Prediction of age at menopause could be improved by multiple AMH measurements; it will be useful in identifying women at risk of early menopause.

Smoking habits and incidence of cardiovascular diseases in men and women: findings of a 12 year follow up among an urban Eastern-Mediterranean population.

BACKGROUND: Despite the strong association of smoking with cardiovascular disease (CVD) and cerebral stroke, the consequences of smoking have not been elucidated among Iranian populations. This study aimed to assess sex-specific incidence of CVDs among an urban Iranian population with different smoking habits. METHODS: Participants were recruited from the Tehran Lipid and Glucose Study (TLGS). Data on socio-demographic features and smoking habits from a sample of 10,400 individuals (4378 men and 6022 women), aged ≥20 years without prior CVD history were analyzed. Participants were followed up for 12 years for incidence of CVD/CHD events. Men were categorized in six groups, including never-, passive, ex-, passive and ex-, occasional and daily smokers. Women were categorized in three groups, i.e. never smokers, passive smokers and ever smokers. Using cox regression model, adjusted hazard ratios (HRs) of incident CVD/CHD were calculated for each group, given never smokers as the reference. RESULTS: In men, HR of CVD was 1.13 (95%CI: 0.80-1.59) in passive smokers, 1.23 (95%CI: 0.91-1.66) in ex-smokers, 1.46 (95%CI: 0.90-2.36) in passive and ex-smokers, 2.33 (95%CI: 1.25-4.33) in occasional smokers and 2.05 (95%CI: 1.57-2.67) in daily smokers. In smokers of ≥21 cigarettes/day, HR of CVD was 3.79 (95%CI: 2.25-6.37), with less risk observed in those who smoked lesser numbers of cigarettes/day. Quitters of ≥15 years were almost risk free. In women, none of the HRs of CVD/CHD were significant. CONCLUSION: An increased risk of incidence of CVD/CHD was found in current male smokers. To confirm and further elaborate these findings, more data of sex-specific studies are required from culturally diverse urban and rural areas of Iran.

Trend of various adiposity indices in women with and without history of gestational diabetes: a population-based cohort study.

BACKGROUND: Data of studies focusing on the trends of adiposity indices among women with prior gestational diabetes mellitus (GDM), are limited and controversial. The aim of this study was to compare overtime trends of adiposity indices in women with and without history of GDM, using data of the long term longitudinal population-based Tehran-Lipid and Glucose-Study (TLGS). METHODS: A total of 3395 eligible women aged (20-50 years), including 801 women with prior history of GDM and 2594 non-GDM controls were recruited from among Tehran-Lipid and Glucose-Study participants. Generalized estimating equations were applied to assess the time trend of adiposity indices including obesity, central obesity, body mass index (BMI), lipid accumulation product index (LAP), visceral adiposity index (VAI) and a body shape index (ABSI) in women with prior GDM and the non-GDM groups after further adjustment for age and BMI. RESULTS: Median follow-up years for the GDM and non-GDM groups were 12.12 and 11.62 years, respectively. Women with GDM at initiation had worse adiposity indices than their healthy counterparts. While overall odds of obesity in women with prior GDM were significantly higher those of the non-GDM groups (OR: 1.35; 95% CI, 1.03-1.7; P = 0.03), both these groups overtime revealed a positive trend in obesity (P trend < 0.001), an incremental trend which was less pronounced in GDM women (OR: 0.87; 95% CI, 0.80, 0.95; P interaction = 0.001). Women with prior GDM had higher odds of central obesity, compared to non-GDM groups (OR: 1.44; 95% CI, 1.06-1.96; P = 0.02) and showed a significant an incremental trend overtime for both groups (P trend < 0.001 for both) without statistically significant interaction in terms of their GDM status (P interaction = 0.134). Mean VAI in women with prior GDM was significantly higher than the non-GDM group (19.7, 95%CI: 6.24, 33.15, P = 0.004), although both groups overtime experienced a negative trend (- 10.9, 95%CI: -13.1, - 2.1, P < 0.001); the GDM group showed a higher decrease in VAI (mean changes: -6.62; 95% CI, - 11,-2.1; P interaction = 0.001). However overtime there was a positive trend in LAP and ABSI among both women with and without prior-GDM, though the mean changes were less obvious in women with prior GDM. CONCLUSION: Women with prior GDM gained better control of their adiposity than non-GDM women. Nevertheless the increasing numbers of individuals with GDM and uncontrolled adiposity indices, require prompt attention be paid to the issue.