Tehran Lipid And Glucose Study Population Research Articles

Legacy of the Tehran Lipid and Glucose Study: Chronic Kidney Disease.

ContextChronic kidney disease (CKD), is correlated with a substantial upsurge in mortality and morbidity worldwide. In this review, we aimed to review the 20-year-findings on CKD of the Tehran lipid and glucose study (TLGS).Evidence AcquisitionWe conducted a systematic review of all studies on CKD that had been performed in the context of TLGS.ResultsAge adjusted prevalence of CKD, according to estimated glomerular filtration rate (eGFR) assessed with the two abbreviated equations of the modification of diet in renal disease (MDRD) and the CKD epidemiology collaboration (CKD-EPI) were 11.3% (95% confidence interval (CI): 10.7, 12.0) and 8.5% (95% CI: 7.9, 9.1), respectively. Using MDRD equation, over a mean follow up of 9.9 years, the incidence density rates of CKD were 285.3 person years in women and 132.6 per 10000 person-years in men. Studies on the TLGS population documented that abdominal adiposity defined as waist circumference (WC) categories (P for trend < 0.02) and waist gain in men (hazard ratio (HR) = 1.7, CI: 1.3, 2.2) significantly affected CKD development. Also, CKD had a significant effect on coronary heart disease (CHD) only in participants with low body mass index (HR = 2.06; CI: 1.28, 3.31 and HR = 2.56; CI: 1.04, 6.31 in men and women, respectively). Moreover, CKD was among the strongest independent predictors of stroke (HR = 2.01, CI: 1.22, 3.33). Also, compared to diabetic patients, an abnormal ECG was more prevalent in moderate CKD (P = 0.02).ConclusionsIncreased waist circumference and waist gain (only in men) were associated with developing CKD in the TLGS population. CKD was an independent predictor of CHD (in lean individuals) and stroke.

Genetic Identification for Non-Communicable Disease: Findings from 20 Years of the Tehran Lipid and Glucose Study.

ContextTehran Lipid and Glucose Study (TLGS), a longitudinal family based cohort study, is the oldest and largest longitudinal family based study in Iran, aimed at investigating effects of environmental, social and biological factors on the health of Tehranians over time. Considering the importance of genetic studies in this aspect, here we present a summary of the important genetic findings, and the potentiality of their contributions to future related projects.Evidence AcquisitionFor all related studies during the past 20 years the search sources were all prominent search engines such as PubMed, Scopus, and Google Scholar with the most proper Medical Subject Headings (MeSH).ResultsThis review summarizes associations of 6 binary phenotypes and 17 quantitative traits with genetic markers in 26 genes. Of the 47 genetic markers, studied most were related to cardio metabolic risk factors. Results of heritability and linkage analysis were also collected and the highest heritability was found to be related to HDL-C (0.5).ConclusionConsidering the opportunity provided by large-scale cohort studies to investigate molecular effects of genetic variants on causality and different omics’ data, genetic studies conducted on TLGS population have had a remarkable success in identifying genetic variants that facilitating a unique genetic database on Iranian populations. The results of genome wide association studies in this population are currently facilitating investigations to define the Iranian genetic differences with other population.

Blood Pressure and Hypertension: Findings from 20 Years of the Tehran Lipid and Glucose Study (TLGS).

ContextHypertension (HTN) is a well-known modifiable risk factor for cardiovascular disease (CVD), chronic kidney disease and mortality. Positive effects of blood pressure (BP) lowering for prevention of CVD and death have been documented in several meta-analyses of randomized controlled trials.Evidence AcquisitionThis review focuses on the key findings derived from the Tehran lipid and glucose study (TLGS) papers on different aspects of BP and HTN.ResultsA prevalence of 23% for HTN has been reported in the TLGS population, aged ≥ 20 years. Over a decade long follow-up, the crude incidence rate (95% CI) of new-onset HTN defined as systolic BP (SBP) ≥ 140 mmHg and/or diastolic BP (DBP) ≥ 90 mmHg, and not using antihypertensive medication was 33.63 (32.0 - 35.3) per 1000 person-years. Age, baseline SBP and body mass index were significant risk factors for development of isolated systolic HTN; regarding isolated diastolic HTN, baseline DBP and waist circumference were recognized as important risk factors whereas age, female gender and marriage were shown to be protective factors. SBP decreased significantly in both diabetic and non-diabetic participants; DBP showed a non-significant decrease in diabetic men and a statistically significant decrease in non-diabetic men. Among women, both those with and without diabetes (DM) generally experienced statistically significant decreases in DBP. Cox proportional hazard models showed that neither SBP nor DBP were associated with incident DM in the total population and in either gender, separately. All BP components were associated with CVD and all-cause mortality in the middle-aged population. Contribution of HTN to cerebrovascular events was also documented in the TLGS participants, aged ≥ 50 years.ConclusionsSeveral important findings regarding BP/HTN have been derived from the TLGS. According to data regarding the prevalence and incidence of preHTN and HTN and their contribution to cardiovascular morbidity and mortality in the TLGS population as a representative sample of Tehranian population, it is recommended that interventions be prioritized for lifestyle modifications for the prevention and appropriate management of preHTN/HTN.

Serum Lipids During 20 Years in the Tehran Lipid and Glucose Study: Prevalence, Trends and Impact on Non-Communicable Diseases.

ContextDyslipidemia, including elevated serum total cholesterol (TC), low density lipoprotein cholesterol (LDL-C), and triglycerides (TG), and low high density lipoprotein cholesterol (HDL-C) is a major modifiable risk factor for non-communicable diseases (NCDs). This review summarizes many of the key findings on lipid measures in the Tehran lipid and glucose study (TLGS), a large scale community-based study with an approximately two decade follow-up.Evidence AcquisitionA systematic literature search was conducted using PubMed, Scopus, Web of Science databases, and the library of the Research Institute for Endocrine Sciences, using the following keywords: Lipid measures, lipid ratios, lipid profile, dyslipidemia, and “Tehran lipid and glucose study”. Articles were categorized based on fields of prevalence, trends, and impact of lipid profile on incident NCDs and mortality.ResultsBetween 1999 - 2001, the prevalence of high risk lipids ranged from 14% (low HDL-C) to 17% (high LDL-C) among adolescents, although among adults the lowest and highest prevalence were observed for low HDL-C (19%) and high TG (28%). Despite favorable trends for lipid parameters among adolescents, adults, and the elderly population, a considerable number of diabetic individuals, failed to achieve the optimum level of serum lipids. During follow-up, consumption of lipid-lowering drugs increased from 1.5 to 9.0% and 3.7 to 11.4% among adult men and women, respectively. The association between different lipid parameters and related ratios for incident type 2 diabetes (T2D), hypertension, metabolic syndrome and cardiovascular diseases differed between genders. Interestingly, each 1-unit increase in TC/HDL-C increased risk of hypertension among women (odds ratio (OR): 1.19, 95% confidence interval (CI): 1.00 - 1.27) and T2D among men (OR: 1.27, 95% CI: 1.06 - 1.51). Moreover, TC, LDL-C, non-HDL-C, Ln-TG, TC/HDL-C, and Ln-TG/HDL were inversely associated with non-cardiovascular mortality.ConclusionsDespite high prevalence of high risk lipid profiles among the TLGS population at baseline, favorable trends were observed in levels of all lipid components, which might be attributable to increased consumption of lipid-lowering medications and improvement in the general knowledge of Iranians regarding limited consumption of hydrogenated oil. Considering the impact of lipid profiles on incident NCDs, more attention should be paid to at-risk groups for screening and treatment purposes.

Health-Related Quality of Life in Tehran Lipid and Glucose Study.

ContextBeyond the objective outcomes of metabolic syndrome (MetS), the association between this syndrome and its patient-centered outcomes need to be investigated in Middle-Eastern countries. This report aims to summarize the Tehran lipid and glucose study (TLGS) findings regarding the association between MetS and health-related quality of life (HRQoL) and its influential factors through the past decade.Evidence AcquisitionThe current review has been conducted on the TLGS published data regarding different aspects of the association between MetS and HRQoL in adult participants through the last decade. To assess HRQoL, the Iranian version of short form health survey (SF-36) was used. To define MetS the most commonly used insulin resistance (IR)-and waist circumference (WC) - based MetS definitions have been applied in the publications reviewed.ResultsAs a whole, MetS was a determinant of poor physical HRQoL only in women (OR: 1.78; 95% CI: 1.21 - 2.61), particularly in those with more component of MetS (P < 0.001). Results further showed that only reproductive aged women with MetS were more likely to report poor PCS compared to those without MetS even after adjusting for age (OR: 1.7, 95% CI: 1.0 - 3.0; P < 0.05). Different structures of MetS and physical HRQoL constructs in men and women as well as age and smoking with significant gender-specific effects on mental HRQoL were factors responsible for the gender specific pattern observed. Considering the duration of MetS, only women with intermittent MetS indicated higher risk for reporting poor PCS (OR: 2.75, 95% CI: 1.19 - 6.37; P < 0.001) compared to those without MetS. The observed sex-specific pattern used to detect poor HRQoL in those with MetS was confirmed by all WC-based definitions except for the American Heart Association/National Heart, Lung, and Blood Institute (AHA/NHLBI) definition. However, none of IR-based definitions could detect poor physical and mental HRQoL in either gender.ConclusionsIn summary, in the TLGS population, the association between MetS and HRQoL followed a sex specific pattern, mainly significant only in women and in the physical aspect.

Socio-Demographic Determinants of Health-Related Quality of Life in Tehran Lipid and Glucose Study (TLGS).

BackgroundHealth-related quality of life (HRQOL) is a multi-dimensional concept that is affected by different variables. A large body of evidence shows that socio-demographic factors have a significant influence on HRQOL. When considering differences in cultural contexts and social values of various countries and the lack of evidence regarding socio-demographic determinants of HRQOL among the Iranian general population, it is important to verify the main socio-demographic determinants of HRQOL in an urban Iranian population.ObjectivesThis study aimed to explore socio-demographic factors associated with HRQOL and to ascertain the determinants of poor HRQOL in participants of the Tehran lipid and glucose study (TLGS).MethodsThe participants included 3491 adults, aged ≥ 20 years, who had participated in the TLGS. To obtain socio-demographic and HRQOL information, participants were interviewed by trained interviewers. Mean HRQOL scores were compared using the student’s t test and analysis of variance (ANOVA). To determine significant determinants of poor HRQOL, multivariate logistic regression analysis was performed.ResultsMean ages of males and females were 47.7 ± 15.6 and 47.8 ± 14.2 years, respectively and 58.6% of participants were male. Males had significantly higher scores compared to females in both the physical and mental domains of HRQOL (P < 0.001). In males, significant determinants of poor physical HRQOL were older age, being married, being unemployed yet having other sources of income, having literacy levels below high school diploma, and having chronic diseases (P < 0.05). In females, however older age and being housewives were significant determinants of poor physical HRQOL (P < 0.05). In addition, significant determinants of poor mental HRQOL were younger age and being single or divorced/widowed in males and younger age and being illiterate as well as having literacy levels below high school diploma in females (P < 0.05).ConclusionsCurrent findings highlight the importance of socio-demographic determinants of HRQOL in both genders, specifically in the physical domain, and demonstrate their roles to be more prominent in males. These findings highlight gender-specific associations between socio-demographic factors and various aspects of HRQOL among the TLGS population, which could be applied in future research focusing on non-communicable diseases and planning health promotion programs.

Increased Risk of CHD in the Presence of rs7865618 (A allele): Tehran Lipid and Glucose Study.

Recent genome-wide association studies (GWAS) in European populations have indicated that the rs12526453 polymorphism located in phosphatase and actin regulator 1 gene (PHACTR1), mapping to chromosome 6p24 and rs7865618 polymorphism in the cyclin-dependent kinase inhibitor B antisense RNA 1 gene (CDKN2B-AS1) on 9p21.3 are associated with coronary heart disease (CHD). This study was carried out to investigate the association of these polymorphisms and CHD in an Iranian population. In the present case-control study, 420 patients with CHD events were recruited from the population of the Tehran lipid and glucose study (TLGS); 407 healthy controls matched for age and sex were selected from the same population. The SNPs rs12526453 and rs7865618 were genotyped using amplification refractory mutation system-polymerase chain reaction (ARMS-PCR). The allele frequency of both SNPs deviated from Hardy-Weinberg equilibrium. The C allele frequency of the rs12526453 (68.5%, P = 0.11) and A allele of the rs7865618 (68.8%, P = 0.09) were the most prevalent alleles in both the case and control groups. The results indicated a significant association between the presence of risk alleles of rs7865618 and CHD in the TLGS population (P = 0.03; OR: 1.73; CI95%: 1.04 - 2.88). Due to the importance of chromosome 9p21 region and its relation with cardiovascular disease, the allelic pattern of its variation should be studied in different populations. The relation between this polymorphism and cardiovascular disease in the studied population confirms the importance of this region.

The Relation between Metabolic Syndrome Risk Factors and Genetic Variations of Apolipoprotein V in Relation with Serum Triglyceride and HDL-C Level.

Metabolic syndrome (MetS) is a multi-factorial disorder with five important components. A high triglyceride level combined with low HDL cholesterol has been reported to be associated with Apolipoprotein A5 (APOA5) gene variations. In this study, we aimed to determine the association of single nucleotide polymorphisms including: rs662799, rs3135506 and rs2075291 in the apolipoprotein A-V (APOA5) gene in relation to MetS component like triglyceride and HDL-C level in Tehran Lipid and Glucose Study (TLGS). Metabolic syndrome was defined according to ATPIII and phenotypes were defined by the National Cholesterol Education Program (NCEP) criteria for MetS. Demographic, biochemical parameters and anthropometric variables were measured. Selected APOA5 gene polymorphisms were genotyped using PCR-RFLP method. From TLGS population, 947 adults, aged 19 - 70 years, were randomly selected and recruited into the study. Mean age, triglyceride and WC were higher and mean HDL was lower in MetS vs. non-MetS group. C allele in rs2075291 showed a significant association with MetS (OR: 2.38, 95% CI; 1.11 - 5.08, P = 1.5 ×10(-2)). The association was shown between higher serum triglyceride and the presence of T allele (P = 4.5 × 10(-4)) and also lower serum HDL-C and the presence of T allele (P = 1.6 × 10(-3)) in rs2075291. Also this association showed between raised waist circumference and C allele in rs3135506 (P = 3.5 × 10(-2) ) and raised systolic and diastolic blood pressure level and C allele of rs662799 (P = 4.5 × 10(-2)). According to the results, there is a relationship between lipid profile and studied polymorphism in the presence of metabolic syndrome. It seems that APOA5 rs2075291 could play an important role in triglyceride and HDL-C level in metabolic syndrome affected, while the association of APOA5 rs662799 polymorphism is still under debate.

The association between inflammatory markers and obesity-related factors in Tehranian adults: Tehran lipid and glucose study.

Obesity considered being a low-grade inflammatory disease. The objective of this study was to examine the association between inflammatory markers (IM) including C-reactive protein (hs-CRP), Interleukin-6 (IL-6), and homocystein (Hcy) and obesity-related factors (e.g. BMI, waist, hip) in adult participants of Tehran lipid and glucose study (TLGS). In this cross-sectional study, 352 individuals (132 men and 220 women), age ≥19 years, were randomly recruited from participants of TLGS population. The serum levels of hs-CRP, IL-6, Hcy were determined using the enzyme linked immunosorbent assay (ELISA) method. Variables were compared by sample t-test. Bivariate linear correlation was estimated using Pearson's correlation coefficient. Linear regression analysis was applied to investigate the association between IMs and anthropometric and biochemical variables. The mean age of participants was 46.1±16.1 years. abdominal obesity was present in 199(56.5%) individuals. levels of hs-CRP and IL-6 increased in the abdominally obese group (1507±3.3 vs. 577.8±4.3 ng/ml P<0.001) (3.6±3.3 vs. 1.9±3.8 pg/ml P< 0.001), and in the same group, the best predictors for hs-CRP, IL-6 and Hcy were waist (WC), waist to height ratio (WHtR) and wrist respectively; hip and WHtR were the best predictors for Hcy and hs-CRP in the normal group. A linear augmentation in hs-CRP and IL-6 levels was observed in association with obesity categorizes. This study provides evidence that abdominally obese individuals had higher levels of IMs. Wrist, waist and WHtR were the best predictors for Hcy, hs-CRP and IL-6 respectively in this group.

The age effect on the association between the scavenger receptor class B type I (SR-BI) polymorphism and HDL-C level: Tehran Lipid and Glucose Study

Introduction: The scavenger receptor class B type I (SR-BI) is a key component in the reverse cholesterol transportation. The aim of this study was to assess the association between exon1 (G → A) polymorphism of SR-BI gene and lipid profiles among the Tehran Lipid and Glucose Study (TLGS) population.Materials and methods: This cross-sectional study included 774 adults (322 males and 452 females) aged 20–70 years who were randomly selected from among TLGS population. Anthropometrical and biochemical variables for participants were measured. Selected SR-BI gene polymorphism was determined with restriction fragment length polymorphism, via Alu restriction enzyme.Results: Minor allele frequency for SR-BI polymorphism in the selected population was 0.159. Allele frequencies were in conformity with Hardy–Weinberg equilibrium. Association between (G → A) SR-BI polymorphism and high density lipoprotein cholesterol (HDL-C) and HDL3 was significant only after adjustment for age as a potential covariate (p = 0.046, 0.041, respectively); however, the results did not improve after adjustment for sex.Discussion: The result of this study confirms the role of age as a potential confounder which could modify the association between the SR-BI single nucleotide polymorphism and HDL-C level.

Transportability of the updated diabetes prediction model from Atherosclerosis Risk in Communities Study to a Middle Eastern adult population: community-based cohort study

We validated the transportability of the updated diabetes prediction model from Atherosclerosis Risk in Communities (ARIC) Study, to a Middle Eastern population. We investigated 3,721 participants of the Tehran Lipid and Glucose Study (TLGS) aged ≥20years, free of diabetes at baseline. They underwent a standard 75gr 2-h post-challenge plasma glucose test that was repeated every 3years using the same protocol. All the models were tested with respect to discrimination and calibration. We confirm the findings of Kahn et al. (Ann Intern Med 150(11):741-751, 2009) in a middle-aged, Middle Eastern population. We obtained the same predictive discrimination for the ARIC model (C statistic: men 0.790 and women 0.829) as for the TLGS' own model (men 0.824 and women 0.847) and validated a good calibration for the updated ARIC diabetes prediction model in the TLGS sample. Among men, optimal cut-point was set to the score of 31 where the maximum value of sensitivity (71.6%) plus specificity (75.3%) was achieved. Among women, the optimal point was set to the score of 38 with sensitivity of 67.1% and specificity of 85.0%. The updated ARIC model predicted the individual diabetes risk with a high level of sensitivity and specificity in the TLGS population, which was comparable with that of original sample. More parsimonious model incorporating age, family history of diabetes, waist circumference, pulse rate, and fasting plasma glucose, which were significantly associated with the risk of incident diabetes in the TLGS population, could be equally effective in predicting diabetes.

Association between CETP Taq1B and LIPC -514C/T polymorphisms with the serum lipid levels in a group of Tehran's population: a cross sectional study

BackgroundLow level of high density lipoprotein cholesterol (HDL-C) has high prevalence in the Tehran Lipid and Glucose Study (TLGS) cohort. About 50% of the inter-individual variation in serum HDL-C levels is genetically determined. Polymorphisms in cholesteryl ester transfer protein (CETP) and hepatic lipase (LIPC) genes have been found to be associated with the metabolism and serum concentration of the HDL-C.ObjectivesTo determine the association between Taq1B polymorphism in CETP gene and -514C/T polymorphism in LIPC gene with serum lipid levels and lipid peroxidation in a subgroup of the TLGS population.ResultsSerum HDL-C level had significant association with CETP Taq1B polymorphism and B2B2 subjects had the highest HDL-C levels compared to B2B1 and B1B1 genotypes (37.9 vs. 36.9 and 35.3 mg/dl, respectively; P = 0.01). However, carriers of "B1" allele, in comparison to the non carriers (B2B2), had significantly lower levels of TC (200.1 vs. 215.2 mg/dl; P = 0.005), HDL-C (35.8 vs. 37.9 mg/dl; P = 0.009) and malondialdehyde MDA (4.5 vs. 5.0 nmol/mL; P=0.031). Carriers of the "T" allele in -514C/T polymorphism in LIPC gene had higher means of HDL-C than non carriers (37.7 vs. 35.7 mg/dl, P = 0.04). No other association was found between -514C/T polymorphism and any other serum lipids or MDA level.ConclusionThis study demonstrates the association between Taq1B and -514C/T polymorphisms in the CETP and LIPC genes with the serum HDL-C levels.