Outcomes of a Longitudinal Population-based Cohort Study and Pragmatic Community Trial: Findings from 20 Years of the Tehran Lipid and Glucose Study

Association between metabolic score for insulin resistance and clinical outcomes: insights from the Tehran lipid and glucose study

BACKGROUND

We aimed to assess the relationship between Metabolic Score for Insulin Resistance (METS-IR) and the incidence of coronary heart disease (CHD), stroke, mortality, diabetes, hypertension, and chronic kidney disease (CKD) in a population from the Middle East and North Africa (MENA) region.

METHOD

Individuals aged ≥ 20 years were enrolled. Cox proportional hazards regression models were applied to assess the association between METS-IR and incident CHD, stroke, all-cause mortality, diabetes, hypertension, and CKD.

RESULTS

Over a median follow-up period of 9-18 years, 1080 (10.6%), 267 (2.6%), 1022 (9.6%), 1382 (16.4%), 2994 (58.5%), and 2002 (23.0%) CHD, stroke, all-cause mortality, diabetes, hypertension, and CKD events occurred, respectively. Compared to the lowest quartile (reference), the hazard ratios (HR) associated with the highest quartile of METS-IR were 1.527 (95% confidence interval [CI]: 1.208-1.930, P for trend 0.001), 1.393 (0.865-2.243, > 0.05), 0.841 (0.682-1.038, > 0.05), 3.277 (2.645-4.060, < 0.001), 1.969 (1.752-2.214, < 0.001), and 1.020 (0.874-1.191, > 0.05) for CHD, stroke, all-cause mortality, diabetes, hypertension, and CKD, respectively. METS-IR, as a continuous variable, was significantly associated with the risk of incident CHD [HR, 95% CI: 1.106, 1.034-1.184], diabetes [1.524, 1.438-1.616], and hypertension [1.321, 1.265-1.380]. These associations were also independent of metabolic syndrome (METS) and remained unchanged in a subgroup of individuals without METS and/or diabetes.

CONCLUSIONS

Increasing levels of METS-IR were significantly associated with a greater risk of incident CHD, diabetes, and hypertension; therefore, this index can be a useful tool for capturing the risk of these clinical outcomes.

The impact of obesity on different glucose tolerance status with incident cardiovascular disease and mortality events over 15 years of follow-up: a pooled cohort analysis

BACKGROUND

The effect of obesity in different glucose tolerance statuses i.e. normoglycemia (NGT), pre-diabetes, and type 2 diabetes (T2DM) on cardiovascular disease (CVD) and mortality has been an area of ongoing debate and uncertainty. In the present study, we aimed to examine the impact of being obese, whether general or central separately, in comparison with non-obese in different glucose tolerance statuses on the above outcomes.

METHODS

The study population included 18,184 participants aged 30-60 years (9927 women) from three longitudinal studies, including Atherosclerosis Risk in Communities, Multi-Ethnic Study of Atherosclerosis, and Tehran Lipid and Glucose Study. Glucose tolerance status was defined as NGT (fasting plasma glucose < 5.55 mmol/L), pre-diabetes (5.55-7.00 mmol/L), and T2DM (≥ 7 mmol/L or taking any medication for diabetes). Moreover, general and central obesity were defined based on body mass index and waist circumference (WC), respectively. Multivariable stratified Cox regression analysis was used to estimate hazard ratios (HRs (95% CI)) for CVD and mortality events.

RESULTS

During a 16-year follow-up, 2733 CVD events, 1101 CV mortality, and 3678 all-cause mortality events were recorded. We observed that being generally obese in comparison with non-obese increased the risk of CV and all-cause mortality in all glucose tolerance statuses; while considering CVD events, only among individuals with T2DM, the presence of general obesity was associated with marginally significant higher risk [1.19 (0.98-1.43); p-value = 0.07]. Regarding central adiposity, multivariate analysis revealed that elevated WC in NGT participants is associated with incident CVD [1.27(1.12-1.46)] and all-cause mortality [1.13(1.00-1.28)]. Moreover, central adiposity increased the risk of CV mortality in pre-diabetes individuals [1.47 (1.11-1.95)].

CONCLUSION

Findings from this pooled prospective cohort studies provide evidence that general obesity shows an unfavorable association with CV and all-cause mortality among the general population irrespective of their glucose tolerance statusThe findings imply that it's important to take into account the requirement and magnitude of weight reduction in people who are obese when offering guidance.

Kidney function decline is associated with mortality events: over a decade of follow-up from Tehran Lipid and Glucose Study

BACKGROUND

To investigate the association between estimated glomerular filtration rate (eGFR) change and mortality risk in a cohort from the Middle East and North Africa region with increasing chronic kidney disease burden.

METHODS

We included 2210 participants aged ≥ 50 years from the prospective cohort of the Tehran Lipid and Glucose Study. The interval for eGFR measurement was between the examinations in 2002-2005 to 2009-2011, and participants were followed through March 2018. Glomerular filtration rate was estimated from serum creatinine using the CKD-EPI creatinine equation. We assessed the association of rapid kidney function decline, (defined as annual eGFR decline ≥ 3 ml/min/1.73 m2 per year); ≥ 30% eGFR decline over six years; and certain drop in kidney function (≥ 25% eGFR decline plus drop in eGFR category) with mortality outcomes.

RESULTS

During a median follow-up of 14.3 years after recruitment, 315 all-cause and 112 cardiovascular disease deaths were recorded. The multivariable-adjusted hazard ratios (HRs) and 95% confidence intervals (CIs) of all-cause death for rapid kidney function decline, ≥ 30% decline in eGFR over 6 years, and drop in kidney function were 1.68 (1.24-2.27), 2.01 (1.46-2.78), and 1.49 (1.11-1.98), respectively. The HRs of all-cause death and for rapid kidney function decline in those without and with chronic kidney disease were 1.41 (1.03-1.91) and 3.38 (1.69-6.76), respectively. Similar findings were observed regarding cardiovascular disease-related and non-cardiovascular disease-related mortality.

CONCLUSIONS

Estimated GFR decline is associated with an increased mortality risk, indicating its ability to provide additional prognostic information beyond traditional risk predictors in the general population.

Sex differences in risk factors for coronary heart disease events: a prospective cohort study in Iran

We investigated sex-specific associations and their differences between major cardiovascular risk factors and the risk of incident coronary heart disease (CHD) and hard CHD (defined as nonfatal myocardial infarction and CHD death). A total of 7518 (3377 men) participants from the Tehran Lipid and Glucose Study were included. Cox models were used to estimate the hazard ratios (HRs) and women-to-men ratios of HRs for CHD events associated with each risk factor. During 20 years of follow-up (1999-2018), 1068 (631 men) and 345 (238 men) new cases of CHD and hard CHD, respectively, were documented. In total population, the incidence rates per 1000 person-years were 9.5 (9.0-10.1) and 2.9 (2.6-3.2) for CHD and hard CHD, respectively. Hypertension, diabetes, pre-diabetes, and a high waist-to-hip ratio (WHR) were associated with a greater HR of hard CHD in women than men; the women-to-men HRs were 2.85 [1.36-5.98], 1.92 [1.11-3.31], 2.04 [1.09-3.80] and 1.42 [1.10-1.82], respectively. Diabetes was associated with a higher HR of CHD in women than men (ratio of HRs 1.49 (1.10-2.01). In conclusion, we found that hypertension, diabetes, pre-diabetes, and high WHR conferred a greater excess risk of CHD events in women than in men, suggesting that Iranian women may require greater attention for the prevention of CHD events.

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 trajectory of body shape index with all-cause and cause-specific mortality: 18 years follow-up

Objectives

The current study aimed to examine how the trajectory of a body shape index (ABSI) could predict mortality in a prospective cohort of 5587 participants.

Methods

A Growth Mixture Model (GMM) was employed to identify ABSI and body shape trajectories spanning from 2000 to 2018. Multivariate Cox regression models with hazard ratio (HR) and 95% confidence intervals (CIs) were built to assess the association of death from all-cause and cardiovascular disease (CVD) with ABSI and body shape trajectories.

Results

We found that individuals with a low ABSI-marked increase (Class II) and high ABSI-marked increase trajectory (Class III) had a higher risk of all-cause (adjusted HR for Class II, 1.37; 95%CI, 1.04-1.79; adjusted HR for Class III, 1.42; 95%CI, 1.05-1.91) and non- CVD mortality (adjusted HR for Class II, 1.38; 95%CI, 1.00-1.91; adjusted HR for Class III, 1.42; 95%CI, 1.00-2.05) as well as an increased risk of CVD (adjusted HR for Class II, 1.40; 95%CI, 1.14-1.71; adjusted HR for Class III, 1.42; 95%CI, 1.13-1.78) and coronary heart disease (CHD) (adjusted HR for Class II, 1.52; 95%CI, 1.18-1.96; adjusted HR for Class III, 1.47; 95%CI, 1.11-1.95. The trajectories of body shape phenotypes did not show any significant associations with mortality, CVD, or CHD events.

Conclusions

ABSI trajectories might be associated with subsequent risk of mortality and CVD events.

Association between estimated glomerular filtration rate slope and cardiovascular disease among individuals with and without diabetes: a prospective cohort study

BACKGROUND

Previous studies have reported an association between a significant decline in estimated glomerular filtration rate (eGFR) over time and an increased risk of cardiovascular disease (CVD). This study aimed to investigate the association between the eGFR slope and CVD among individuals with and without diabetes.

METHODS

This prospective cohort study was conducted within the Tehran Lipid and Glucose Study (TLGS) framework. We studied 6919 adults aged 20-70 years, including 985 with diabetes and 5934 without diabetes. The eGFR slope was determined based on repeated measurements of eGFR through linear mixed-effects models. A multivariable Cox proportional hazard model was employed to evaluate the association between eGFR slope, both in continuous and categorical form, and the risk of CVD.

RESULTS

The slopes of eGFR exhibited a bell-shaped distribution, with a mean (standard deviation (SD)) of -0.63 (0.13) and - 0.70 (0.14) ml/min per 1.73 m2 per year in individuals with and without diabetes, respectively. During a median follow-up of 8.22 years, following the 9-year eGFR slope ascertainment period, a total of 551 CVD events (195 in patients with diabetes) were observed. Among individuals with diabetes, a steeper decline in eGFR slope was significantly associated with a higher risk of CVD events, even after adjusting for baseline eGFR, demographic factors, and traditional risk factors for CVD; slopes of (-1.05 to -0.74) and (-0.60 to -0.52) were associated with 2.12 and %64 higher risks for CVD, respectively, compared with a slope of (-0.51 to 0.16). Among individuals without diabetes, the annual eGFR slope did not show a significant association with the risk of CVD.

CONCLUSION

Monitoring the eGFR slope may serve as a potential predictor of CVD risk in individuals with diabetes.

The impact of general and central obesity for all-cause hospitalization among Iranian adults: a 20 year follow-up-results from the TLGS cohort

BACKGROUND

Few studies have examined the effect of obesity indices on total number of hospitalizations. We examined the associations between body mass index (BMI) and waist circumference (WC) and rate of all-cause hospitalizations among Iranian adult participated in the Tehran Lipid and Glucose Study cohort.

METHODS

This study included 8202 individuals (3727 men) aged ≥ 30 years, who were followed for a median of 18 years. Participants were categorized into three groups according to their baseline BMI: normal weight, overweight and obese. In addition, they were classified according to WC in two categories: normal WC and high WC. Negative Binomial regression model was used to estimate the incidence rate ratios (IRRs) and 95% confidence interval (95% CI) of all-cause hospitalizations in relation to obesity indices.

RESULTS

The overall crude rate of all-cause hospitalizations were 77.6 (95% CI, 73.9-81.2) and 76.9 (73.4-80.3) per 1000 person-year in men and women, respectively. The covariate adjusted rate of all-cause hospitalizations was 27% higher in obese men than normal weight men (IRR (95% CI): 1.27 (1.11-1.42)). Among women, overweight and obese individuals had 17% (1.17 (1.03-1.31)) and 40% (1.40 (1.23-1.56)) higher rate of hospitalization compared to normal weight women. Having high WC was associated with 18% (1.18 (1.08-1.29)) and 30% (1.30 (1.18-1.41)) higher rate of all-cause hospitalization in men and women, respectively.

CONCLUSIONS

Obesity and high WC were associated with increased hospitalization rates during long-term follow-up. Our findings suggests that successful obesity prevention programs may decrease the number of hospitalizations, particularly, in women.

The impact of long-term exposure to PM10, SO2, O3, NO2, and CO on incident dysglycemia: a population-based cohort study

To examine the associations between long-term exposure to five major air pollutants including SO₂, PM₁₀, O₃, NO₂, and CO_, and incident dysglycemia, impaired fasting glucose (IFG), and diabetes, separately. A total of 4254 (1720 men) normoglycemic individuals aged 20-69 years at baseline were followed from 2001 to 2018 every 3 years. To measure the long-term hazards of air pollutants for incident dysglycemia, the Weibull proportional hazards models for every 10-unit increment adjusted for diabetes risk factors were fitted. The air pollutants were put in the models in the form of averages of 1-, 2-, and 3-year periods. During a median follow-up of 12.2 years, we observed 1780 dysglycemia events. In contrast to NO₂, the increase in SO₂, O₃, and PM₁₀ levels were significantly associated with a higher risk of dysglycemia and IFG in all time spans excluding PM₁₀ at 2 years. The largest hazard ratios for incident dysglycemia and IFG were attributable to PM₁₀ in 3 years (2.20 (95% CI 1.67, 2.89) and 2.08 (1.55, 2.80), respectively). Moreover, exposure to all the pollutants except NO₂ in 1 year (0.89 (0.80, 0.98)) had no significant associations with incident diabetes. There was a signal that younger (< 45 years) and never-smoker individuals were more predispose to dysglycemic effects of air pollution (all P for interactions > 0.03). Our findings suggested that long-term exposure to air pollution increased incident dysglycemia risk, the effect which was mainly attributable to IFG status.

Mean versus variability of lipid measurements over 6 years and incident cardiovascular events: More than a decade follow-up

Background

Lipid variability (LV) has emerged as a contributor to the incidence of cardiovascular diseases (CVD), even after considering the effect of mean lipid levels. However, these associations have not been examined among people in the Middle East and North Africa (MENA) region. We aimed to investigate the association of 6-year mean lipid levels versus lipid variability with the risk of CVD among an Iranian population.

Methods

A total of 3,700 Iranian adults aged ≥ 30 years, with 3 lipid profile measurements, were followed up for incident CVD until March 2018. Lipid variability was measured as standard deviation (SD), coefficient of variation (CV), average real variability (ARV), and variability independent of mean (VIM). The effects of mean lipid levels and LV on CVD risk were assessed using multivariate Cox proportional hazard models.

Results

During a median 14.5-year follow-up, 349 cases of CVD were recorded. Each 1-SD increase in the mean levels of total cholesterol (TC), low-density lipoprotein cholesterol (LDL-C), TC/high-density lipoprotein cholesterol (HDL-C), and non-HDL-C increased the risk of CVD by about 26-29%; for HDL-C, the risk was significantly lower by 12% (all p-values < 0.05); these associations resisted after adjustment for their different LV indices. Considering LV, each 1-SD increment in SD and ARV variability indices for TC and TC/HDL-C increased the risk of CVD by about 10%; however, these associations reached null after further adjustment for their mean values. The effect of TC/HDL-C variability (measured as SD) and mean lipid levels, except for LDL-C, on CVD risk was generally more pronounced in the non-elderly population.

Conclusion

Six-year mean lipid levels were associated with an increased future risk of incident CVD, whereas LV were not. Our findings highlight the importance of achieving normal lipid levels over time, but not necessarily consistent, for averting adverse clinical outcomes.

The clinical value of metabolic syndrome and its components with respect to sudden cardiac death using different definitions: Two decades of follow-up from the Tehran Lipid and Glucose Study

BACKGROUND

To evaluate the impact of different definitions of metabolic syndrome (MetS) and their components on the risk of sudden cardiac death (SCD) among the Iranian population according to the World Health Organization (WHO), International Diabetes Federation (IDF), Adult Treatment Panel III (ATP III), and Joint Interim Statement (JIS) criteria.

METHODS

The study population included a total of 5,079 participants (2,785 women) aged ≥ 40 years, free of cardiovascular disease (CVD) at baseline. Participants were followed for incident SCD annually up to 20 March 2018. Multivariable Cox proportional hazards regression models were applied to estimate the hazard ratios (HRs) and 95% confidence intervals (CIs) of MetS and its components for incident SCD.

RESULTS

The prevalence of MetS ranged from 27.16% to 50.81%, depending on the criteria used. Over a median of 17.9 years of follow-up, 182 SCD events occurred. The WHO, IDF, and JIS definitions were strong predictors of SCD with multivariable-adjusted HRs (95% CI) of 1.68 (1.20-2.35), 1.51 (1.12-2.03), and 1.47 (1.08-1.98), respectively; these associations significantly attenuated after further adjustment for MetS components. MetS by the ATP III definition was not associated with the risk of SCD after controlling for antihypertensive, glucose-lowering, and lipid-lowering medication use. Among the components of MetS, high blood pressure (WHO definition), high waist circumference (using the national cutoff of ≥ 95 cm), and high glucose component by the JIS/IDF definitions remained independent predictors of SCD with HRs of 1.79 (1.29-2.48), 1.46 (1.07-2.00), and 1.52 (1.12-2.05), respectively.

CONCLUSIONS

The constellation of MetS, except for when defined with ATP III definition, is a marker for identifying individuals at higher risk for SCD; however, not independent of its components. Among MetS components, abdominal obesity using the population-specific cutoff point, high glucose component (JIS/IDF definitions), and high blood pressure (WHO definition) were independent predictors of SCD.

Changes in Fasting plasma glucose status and risk of mortality events in individuals without diabetes over two decades of Follow-up: a pooled cohort analysis

BACKGROUND

We aimed to assess the gender-specific impact of 3-year changes in fasting plasma glucose (FPG) status on the risk of all-cause, cardiovascular (CV), and cancer mortality in individuals without type 2 diabetes (T2DM) during an 18-year follow-up.

METHODS

The study population included 14,378 participants aged 30-60 years (8272 women) from three population-based cohort studies, including Atherosclerosis Risk in Communities, Multi-Ethnic Study of Atherosclerosis, and Tehran Lipid and Glucose Study. Subjects were classified into six categories based on the approximately three-year changes in FPG status: (1) normal FPG (NFG) to NFG (reference category); (2) NFG to impaired fasting glucose (IFG) (i.e., 126 > FPG ≥ 100 mg/dl); (3) NFG to T2DM; (4) IFG to NFG; (5) IFG to IFG; (6) IFG to T2DM. Multivariable stratified Cox regression, adjusting for age, body mass index (BMI), BMI-Change, smoking status, hypertension, and hypercholesterolemia was used to estimate hazard ratios (HRs (95% CI)) for all-cause and cause-specific mortality events. Women-to-men ratios of HRs (RHRs) for each category were also estimated.

RESULTS

During follow-up, 2,362 all-cause mortality events were recorded. Among women, all categories of FPG change, excluding IFG-NFG (HR, 95%CI 1.24 (0.98-1.57), p = 0.07), were associated with a higher risk of all-cause mortality compared to the NFG-NFG category. Moreover, women in IFG-T2DM group were at increased risk for CV mortality (2.21 (1.42-3.44)). We also found that women in NFG-IFG (1.52 (1.20-1.91)), NFG-T2DM (2.90 (1.52-5.51)), and IFG-IFG (1.30 (1.02-1.66)) categories had a higher risk for cancer mortality. However, among men, a higher risk of all-cause mortality was found for only two groups of NFG-T2DM (1.78 (1.15-2.74)) and IFG-T2DM (1.34 (1.04-1.72)). Women with IFG-IFG had a 24% higher risk for all-cause mortality events than their men counterparts (RHR; 1.24 (1.01-1.54)). After further adjustment for physical activity, results were in line with the main findings, excluding T2DM up to six years after the measurement period and early mortality events.

CONCLUSION

In women, the IFG status, whether as incident, persistent, or converted to T2DM, had a higher risk for mortality events; however, among men, only conversion to T2DM conferred an excess risk of all-cause mortality.

The relationship between glucose intolerance status and risk of hospitalization during two decades of follow-up: Tehran lipid and glucose study

OBJECTIVE

To assess the relationship between glucose intolerance statuses at baseline defined as normal glucose tolerance (NGT), pre-diabetes, newly diagnosed (NDM) and known diabetes mellitus (KDM) and all-cause hospitalization among Iranian men and women during 20 years of follow-up.

RESEARCH DESIGN AND METHODS

This study included 8,014 individuals (3,836 men) ≥30 years from the cohort of Tehran Lipid and Glucose Study. Incidence rate ratios (IRRs) and (95% confidence interval (95% CI) for three groups of pre-diabetes, NDM and KDM was estimated using the Negative Binomial regression model, considering NGT group as reference group. Regression models were adjusted for age, body mass index, hypertension, chronic kidney disease, and cardiovascular disease (CVD).

RESULTS

Among men, compared with NGT group, those with pre-diabetes, NDM and KDM had higher incidence rate for hospitalization, with IRRs (95% CI) of 1.08 (0.96-1.20), 1.38 (1.20-1.57) and 1.96 (1.66-2.26), respectively, after adjusting for confounders. The corresponding values were 1.07 (0.96-1.17), 1.40 (1.21-1.59) and 2.07 (1.72-2.42) for women. Men with diabetes, generally had a higher rate of hospitalization for CVD rather than their female counterparts (IRRs: 1.46; 1.17-1.74). In patients with diabetes, the most common causes of hospitalization were macrovascular complications (i.e. coronary heart disease and stroke). Moreover, among the individuals with diabetes, those with poor glycaemic control (fasting plasma glucose (FPG) >10 mmol/l) had 39% higher rate of hospitalization than those with fair glycaemic control (FPG <10 mmol/l) (1.39; 1.12-1.65), adjusted for confounders.

CONCLUSION

Pre-diabetes, NDM, and KDM were associated with increased hospitalization rates during long-term follow-up. Interventions such as lifestyle modification or pharmacological therapies aiming to slow down the pre-diabetes and fair control of diabetes might potentially decrease the rate of hospitalization.Key messagesNDM and KDM status both increased rate of all-cause hospitalization.CVD and T2DM complication were the most common cause of hospitalization among patients with diabetes.Hospitalization due to recurrent CHD was significantly higher in men with diabetes than their female counterparts.

Dietary oxalate-calcium balance and the incidence of hypertension and chronic kidney disease: a prospective study among an Asian population

Background

The potential effects of dietary oxalate (Ox) intake on cardio-renal function have remained unestablished. We evaluated the effect of usual Ox intake and its interaction with dietary calcium (Ca) on incident hypertension (HTN) and chronic kidney disease (CKD).

Methods

Adult men and women, free of HTN and CKD at baseline (2006–2008), were recruited. Dietary intakes were assessed using a validated food frequency questionnaire, and the outcomes were documented up to 2014–2017. Multivariate Cox proportional hazard regression models were used to estimate the development of HTN and CKD in relation to Ox intakes. Repeated-measures generalized estimating equation (GEE) linear regression models were used to assess possible effect of Ox-intake on the estimated glomerular filtration rate (eGFR) and blood pressure levels over eight years.

Results

Dietary Ox intakes were positively associated with incident CKD (HR = 2.59, 95% CI = 1.46–4.64) and HTN (HR = 1.79, 95% CI = 1.05–3.04). Compared to high-Ca consumers, subjects who had lower Ca intakes (< 990 vs. 1580 mg/d) had a higher incidence of CKD and HTN (HR = 2.43, 95% CI = 1.06–5.55, and HR = 1.72, 95% CI = 0.76–3.78). Participants with higher intakes of Ox (> 220 vs. < 150 mg/d) had lower eGFR values (75.3, 95% CI = 75.0–76.5 vs. 77.3, 95% CI = 76.6–78.1 mL/min/1.73m², P_time×group = 0.004) and higher SBP levels (112, 95% CI = 111–113 vs. 109, 95% CI = 108–110 mmHg, P_time×group = 0.007) overtime.

Conclusion

Higher dietary Ox intake may increase the risk of HTN and CKD. The relation between dietary Ox and risk of HTN and CKD seems to be varied by Ca intake, and subjects with lower Ca intakes may be more burdened by excessive amounts of dietary Ox.

Gender differences in changes in metabolic syndrome status and its components and risk of cardiovascular disease: a longitudinal cohort study

Background

We aimed to investigate the gender difference in the association between changes in metabolic syndrome (MetS) and its components with the risk of cardiovascular disease (CVD) and coronary heart disease (CHD) among adult participants in the Tehran lipid and glucose study cohort.

Methods

A total of 4624 adults (aged ≥ 30 years) who participated in two Phases 2 (2002–2005) and 3 (2005–2008) were included and followed up until 2018. Based on the status of MetS and its components in two phases, we divided participants into four groups: MetS-free, MetS-developed, MetS-recovery and MetS-stable groups, and similar categories were defined for MetS components. Multiple Cox regression models were used to estimate the adjusted hazard ratios (HRs) and 95% confidence intervals (95% CIs), and women-to-men ratios of HRs (RHRs).

Results

During a median follow-up of 11.6 years, 619 CVD events (292 women) and 512 CHD events (230 women) occurred. In both genders, the MetS-stable group had the highest risk of CVD and CHD, compared with the MetS-free group, but the associations were stronger in women than men: the HR (95% CI) were (2.76, 2.00-3.82) and (3.08, 2.15–4.40) for CVD and CHD, respectively, in women, and (1.60, 1.23–2.09) and (1.74, 1.30–2.31) for men. The multivariate adjusted women-to-men RHRs were (1.72, 1.16–2.56) for CVD and (1.77, 1.14–2.73) for CHD. Only among women, the risks for CVD in MetS-recovery group (1.67, 1.06–2.63) and MetS-developed group (1.89, 1.16–3.06|) were higher than MetS-free group. For CHD, women in MetS-developed group (1.86, 1.07–3.22) had higher risk than MetS-free group. However, no evidence of gender difference was observed in these associations. Among MetS components, persistent high blood pressure (BP) conferred greater risk for CVD and CHD in women than men; the women-to-men RHRs of CVD and CHD for high BP-stable groups were 1.54 (1.05–2.26) and 1.62 (1.07–2.47), respectively. For CHD events, persistent high fasting plasma glucose was associated with greater risk in women than men with women-to-men RHRs of 1.62 (1.09–2.40).

Conclusion

Change in MetS and its key components were associated with different risks for CVD events in both genders, with generally stronger associations in women than men.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12933-022-01665-8.

Differences in the impact of impaired glucose status on clinical outcomes in younger and older adults: Over a decade of follow-up in the Tehran lipid and glucose study

Introduction

Studies found that the impact of dysglycemia on microvascular, macrovascular events and mortality outcomes were different between the younger vs. older population. We aimed to investigate the age-specific association of prediabetes with clinical outcomes including type 2 diabetes (T2DM), hypertension, chronic kidney disease (CKD), cardiovascular disease (CVD), and mortality.

Materials and methods

A total of 5,970 Iranians (3,829 women) aged ≥30 years, without T2DM, were included. The age-specific (<60 and ≥60 years; minimum p-value for interaction = 0.001) multivariable-adjusted Cox regression was done to calculate the hazard ratios (HRs) and 95% confidence intervals (CIs) of the impaired glucose status including impaired fasting glucose (IFG) vs. normal fasting glucose (NFG), impaired glucose tolerance (IGT) vs. normal glucose tolerance (NGT), and IFG&IGT vs. NFG/NGT with each outcome.

Results

Among individuals aged ≥60 years, the prevalence of impaired glucose status (IFG, IGT, or both) was about 2 times higher compared to those aged <60. Age-specific association between prediabetes and incident hypertension was found for those aged <60 years; [HR (95% CI); IFG: 1.38 (1.16–1.65), IGT: 1.51 (1.26–1.81), and IFG&IGT: 1.62 (1.21–2.12)]. For CVD, in all impaired glycemic states, those aged <60 were at higher significant risk [IFG: 1.39 (1.09–1.77), IGT: 1.53 (1.19–1.97), and IFG&IGT: 1.60 (1.14–2.25)]. Stratified analyses showed similar associations for IFG and IGT with non-CV mortality 1.71 (1.04–2.80) and 2.12 (1.30–3.46), respectively, and for all-cause mortality among those aged <60 years [IFG: 1.63 (1.08–2.45) and IGT: 1.82 (1.20–2.76)]. In both age groups, all glycemic status groups were significantly associated with T2DM but not with CKD and CV mortality.

Conclusions

The high prevalence of prediabetes particularly among the elderly population, limited resources, and the observed significant age differences in the impact of prediabetes states on different clinical outcomes calls for multicomponent intervention strategies by policy health makers, including lifestyle and possible pharmacological therapy, with the priority for the young Iranian population.

Sex differences in the association between diabetes and hypertension and the risk of stroke: cohort of the Tehran Lipid and Glucose Study

Background

We assessed the sex differences in the association between blood pressure categories and glucose intolerance status with overall and ischemic stroke among Iranian adults.

Methods

This prospective study was conducted on 5349 individuals (2446 men) aged ≥ 40 years. Cox models were used to estimate adjusted hazard ratios (HRs) and men-to-women ratios of HRs (RHRs) of overall and ischemic stroke for systolic (SBP) and diastolic (DBP) blood pressure, pre-hypertension, hypertension, fasting plasma glucose (FPG), pre-diabetes and type 2 diabetes (T2D).

Results

Each 0.55 mmol/L increase in FPG was associated with a higher HR of overall stroke in men than women [RHRs 1.05 (1.01–1.09)]. The associations between each 10 mmHg increase in DBP and stroke events were stronger in men than women, with RHRs of 1.20 (1.00–1.45) and 1.29 (1.04–1.60) for overall and ischemic stroke, respectively. Hypertension was associated with a higher HR of overall [RHRs: 2.41 (1.21–4.8)] and ischemic stroke [2.37 (1.12–5.01)] in men than women. We also found that T2D was associated with higher risks of overall and ischemic stroke in men than women: the RHRs were 2.16 (1.24–3.75) and 1.93 (1.05–3.55) for overall and ischemic stroke, respectively.

Conclusion

Hypertension and T2D induced higher risk of overall and ischemic stroke in men than women among Iranian population.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13293-022-00421-7.

The associations between diastolic blood pressure and stroke events were stronger in men than women.

The fasting blood plasma level was associated with higher risk of stroke events in men than women.

Hypertension and diabetes were associated with higher risk of stroke events in men than women.

The association between systolic blood pressure with ischemic stroke was higher in men than women.

Dietary acid load and risk of cardiovascular disease: a prospective population-based study

BACKGROUND AND AIM

Considering the inconsistencies in the cardiovascular effects of dietary acid load and the impact of dietary acidity on the acid-base homeostasis within the body, we aimed to assess the association of dietary acid load and the risk of cardiovascular disease (CVD) in a prospective community-based study.

MATERIALS AND METHODS

Participants (n = 2369) free of CVD at baseline (2006-2008) were included from the Tehran Lipid and Glucose Study (TLGS) and followed up for a mean of 6.7 ± 1.4 years. Dietary intakes of the participants were assessed using a semi-quantitative food frequency questionnaire (FFQ). The dietary acid load was evaluated by Potential Renal Acid Load (PRAL) and Net Endogenous Acid Production (NEAP) scores. Both scores have used the macronutrient and micronutrient data of the Food Frequency Questionnaires. Multivariate Cox proportional hazard regression models were used to estimate the 6-years incident risk of CVDs across tertiles of PRAL and NEAP scores.

RESULTS

Mean age and body mass index of participants were 38.5 ± 13.3 years and 26.6 ± 4.8 kg/m² at baseline. Within 6.7 ± 1.4 years of follow-up, 79 cases of cardiovascular events were reported. NEAP was significantly associated with the incidence of CVDs (HRs = 0.50, CI 0.32-0.96; P for trend = 0.032); however, after adjusting for potential confounders, no significant associations were observed between PRAL and NEAP scores and the risk of CVDs.

CONCLUSIONS

This study failed to obtain independent associations between dietary acid load and the incidence of CVDs among an Asian population.

Anthropometric indices and the risk of incident sudden cardiac death among adults with and without diabetes: over 15 years of follow-up in The Tehran Lipid and Glucose Study

BACKGROUND

We investigated the association of anthropometric indices including body mass index (BMI), waist circumference (WC), waist-to-hip ratio (WHR), waist-to-height ratio (WHtR), and hip circumference (HC) with the risk of incident sudden cardiac death (SCD) among Iranian population with and without type 2 diabetes mellitus (T2DM).

METHODS

The study population included 9,089 subjects without and 1,185 subjects with T2DM, aged ≥ 20 years. Participants were recruited in 1999-2001 or 2001-2005, and followed for incident SCD annually, up to 20 March 2018. Multivariate Cox proportional hazard models, adjusted for traditional risk factors of cardiovascular disease, were applied to estimate hazard ratios (HRs) and 95% confidence intervals (CIs) of anthropometric indices (as continuous and categorical variables).

RESULTS

During a follow-up of over 15 years, 144 (1.58%) and 86 (7.26%) incident SCD occurred in non-T2DM and T2DM groups, respectively. Among non-T2DM group, a 1 standard deviation (SD) increase in WHtR was associated with higher risk of incident SCD by a HR of 1.23 (95% CI: 1.00-1.50) in the multivariable model. From the first quartile to the fourth quartile of WHtR, the trend of SCD risk was significant in age- and sex-adjusted analysis (P-value for trend: 0.041). Other indices did not show significant associations with SCD. Among T2DM group, a 1 SD increase in WHR had a HR of 1.36 (1.05-1.76) in the multivariable model. Considering WHR as categorical variables, the trend of SCD risk across quartiles of WHR was significant. Furthermore, a 1 SD increase in HC led to reduced risk of incident SCD with a HR of 0.75 (0.58-0.97) in multivariable analysis; this lower risk remained significant even after adjustment for WC. Compared to the first quartile, the fourth quartile of HC also showed a HR of 0.50 (0.25-0.99) (P-value for trend = 0.018). BMI, WC, and WHtR did not have significant associations with incident SCD.

CONCLUSION

In our long-term population-based study, we demonstrated central but not general obesity (as assessed by WHR in participants with T2DM, and WHtR in participants without T2DM) as a herald of incident SCD. Moreover, HC can have an inverse association with SCD among participants with T2DM.

Trajectories of cardiovascular disease risk and their association with the incidence of cardiovascular events over 18 years of follow-up: The Tehran Lipid and Glucose study

BACKGROUND

Understanding long-term patterns (trajectories) of cardiovascular diseases (CVD) risk and identifying different sub-groups with the same underlying risk patterns could help facilitate targeted cardiovascular prevention programs.

METHODS

A total of 3699 participants of the Tehran Lipid and Glucose Study (TLGS) (43% men, mean age = 53.2 years), free of CVD at baseline in 1999-2001 and attending at least one re-examination cycle between the second (2002-2005) and fourth cycles (2009-2011) were included. We examined trajectories of CVD risk, based on the ACC/AHA pooled cohort equation, over ten years and subsequent risks of incident CVD during eight years later. We estimated trajectories of CVD risk using group-based trajectory modeling. The prospective association of identified trajectories with CVD was examined using Cox proportional hazard model.

RESULTS

Three distinct trajectories were identified (low-low, medium-medium, and high-high risk). The high-high and medium-medium CVD risk trajectories had an increasing trend of risk during the time; still, this rising trend was disappeared after removing the effect of increasing age. Upon a median 8.4 years follow-up, 146 CVD events occurred. After adjusting for age, the medium-medium and high-high trajectories had a 2.4-fold (95% CI 1.46-3.97) and 3.46-fold (95% CI 1.56-7.70) risk of CVD compared with the low-low group, respectively. In all trajectory groups, unfavorable increasing in fasting glucose, but favorable raising in HDL and decreasing smoking and total cholesterol happened over time.

CONCLUSIONS

Although the risk trajectories were stable during the time, different risk factors varied differently in each trajectory. These findings emphasize the importance of attention to each risk factor separately and implementing preventive strategies that optimize CVD risk factors besides the CVD risk.

Association of dietary fatty acids and the incidence risk of cardiovascular disease in adults: the Tehran Lipid and Glucose Prospective Study

Background

Considering the inconsistent available findings regarding the cardioprotective effect of dietary fatty acid composition, we prospectively examined the feasible association between the dietary fatty acids and the cardiovascular disease (CVD) incidence in framework of the population-based Tehran Lipid and Glucose Study.

Methods

A total of 2369 participants (19–70 years, 43.5% men) without CVD at baseline (2006–2008) were included and followed-up for 6.7 years. Fatty acids’ dietary intake was estimated using a 168-item semi-quantitative food frequency questionnaire. The CVD incidence risk across tertiles of dietary fatty acids was predicted via Cox proportional hazards regression models.

Results

The average age and body mass index of the included population were 38.5 ± 13.3 years and 26.6 ± 4.8 kg/m² at baseline. Over 6.7 years of follow-up, 79 cases of CVD were detected. The risk of CVD was lower in upper tertile of monounsaturated fatty acids, oleic acid, and docosahexaenoic acid + eicosapentaenoic acid among the tertiles. No significant associations were found between total fat, saturated and polyunsaturated fatty acids’ intake, and CVD.

Conclusions

Our results suggest that the dietary fatty acid composition might affect the incidence risk of CVD within the Iranian population.

Long-term effectiveness of a lifestyle intervention on the prevention of type 2 diabetes in a middle-income country

This study aims to assess the effects of a community-based lifestyle intervention program on the incidence of type 2 diabetes (T2D). For this purpose, three communities in Tehran were chosen; one community received a face-to-face educational session embedded in a long-term community-wide lifestyle intervention aimed at supporting lifestyle changes. We followed up 9,204 participants (control: 5,739, intervention: 3,465) triennially from 1999 to 2015 (Waves 1-5). After a median follow-up of 3.5 years (wave 2), the risk of T2D was 30% lower in the intervention community as compared with two control communities by (Hazard-ratio: 0.70 [95% CI 0.53; 0.91]); however, the difference was not statistically significant in the following waves. After a median follow-up of 11.9 years (wave 5), there was a non-significant 6% reduction in the incidence of T2D in the intervention group as compared to the control group (Hazard-ratio: 0.94 [0.81, 1.08]). Moreover, after 11.9 years of follow-up, the intervention significantly improved the diet quality measured by the Dietary Approaches to Stop Hypertension concordance (DASH) score. Mean difference in DASH score in the intervention group versus control group was 0.2 [95% CI 0.1; 0.3]. In conclusion, the intervention prevented T2D by 30% in the short-term (3.5 years) but not long-term; however, effects on improvement of the diet maintained in the long-term.Registration: This study is registered at IRCT, a WHO primary registry ( https://irct.ir ). The registration date 39 is 2008-10-29 and the IRCT registration number is IRCT138705301058N1.

Multi-state analysis of hypertension and mortality: application of semi-Markov model in a longitudinal cohort study

Background

Most previous research has studied the association of hypertension with cardiovascular disease (CVD) and all-cause mortality by focusing on the transition from the initial state to a single outcome. We investigated the impact of hypertension, defined according to the 2017 American College of Cardiology/American Heart Association (ACC/AHA) (new) and the Seventh Report of the Joint National Committee (JNC7) (old), on CVD death and all-cause mortality considering non-fatal CVD as an intermediate event between two CVD-free and mortality states.

Methods

A total of 3002 Iranian population (47.4% men), aged ≥50 years were followed from 1999 to 2014. Two multi-state semi-Markov models with three transitions were defined for CVD death and all-cause mortality as two outcomes. The multivariable Cox model was used to estimate the effect of hypertension on transition hazards. The mean of 15-year life expectancy of participants in each transition was estimated using the restricted mean survival time.

Results

The ACC/AHA guideline increased the prevalence of hypertension from 43.3 to 68.6%. Among CVD-free individuals, hypertension was significantly associated with increased risk of non-fatal CVD [Hazard Ratio, 1.52 (1.28–1.81) and 1.48 (1.21–1.80)], CVD death [2.96 (2.06–4.25) and 1.98 (1.30–3.04)] and all-cause mortality [1.64 (1.32–2.05) and 1.31 (1.01–1.69)] according the old and new guidelines, respectively. However, after incident non-fatal CVD, the association between hypertension and mortality events was not significant according to both definitions. Hypertensive participants experienced a first non-fatal CVD about 0.9 and 0.6 years earlier than normotensive population according to JNC7 and the 2017 ACC/AHA guidelines, respectively.

Conclusion

Hypertension, according to JNC7 and the ACC/AHA guidelines, significantly increased the risk of mortality events among CVD-free population although the risk was attenuated using ACC/AHA guideline. Hypertension also decreased the number of years lived without CVD and early onset of CVD, and consequently, an increase in the time spent with these diseases. After non-fatal CVD, hypertension had no significant impact on mortality risk according to both guidelines.

External validation of the European risk assessment tool for chronic cardio-metabolic disorders in a Middle Eastern population

BACKGROUND

High burden of chronic cardio-metabolic disorders including type 2 diabetes mellitus (T2DM), chronic kidney disease (CKD), and cardiovascular disease (CVD) have been reported in the Middle East and North Africa region. We aimed to externally validate a non-laboratory risk assessment tool for the prediction of the chronic cardio-metabolic disorders in the Iranian population.

METHODS

The predictors included age, body mass index, waist circumference, use of antihypertensive medications, current smoking, and family history of cardiovascular disease and/or diabetes. For external validation of the model in the Tehran lipids and glucose study (TLGS), the Area under the curve (AUC) and the Hosmer-Lemeshow (HL) goodness of fit test were performed for discrimination and calibration, respectively.

RESULTS

Among 1310 men and 1960 women aged 28-85 years, 29.5% and 47.4% experienced chronic cardio-metabolic disorders during the 6 and 9-year follow-up, respectively. The model showed acceptable discrimination, with an AUC of 0.72 (95% CI 0.69-0.75) for men and 0.73 (95% CI 0.71-0.76) for women. The calibration of the model was good for both genders (min HL P = 0.5). Considering separate outcomes, AUC was highest for CKD (0.76 (95% CI 0.72-0.79)) and lowest for T2DM (0.65 (95% CI 0.61-0.69)), in men. As for women, AUC was highest for CVD (0.82 (95% CI 0.78-0.86)) and lowest for T2DM (0.69 (95% CI 0.66-0.73)). The 9-year follow-up demonstrated almost similar performances compared to the 6-year follow-up. Using Cox regression in place of logistic multivariable analysis, model's discrimination and calibration were reduced for prediction of chronic cardio-metabolic disorders; the issue which had more effect on the prediction of incident CKD among women. Moreover, adding data of educational levels and marital status did not improve, the discrimination and calibration in the enhanced model.

CONCLUSION

This model showed acceptable discrimination and good calibration for risk prediction of chronic cardio-metabolic disorders in short and long-term follow-up in the Iranian population.

Impact of secondhand smoke exposure in former smokers on their subsequent risk of coronary heart disease: evidence from the population-based cohort of the Tehran Lipid and Glucose Study

OBJECTIVES

Cigarette smoking is an established, strong, and modifiable risk factor for coronary heart disease (CHD). However, little research has investigated CHD risk in former smokers who continue to be exposed to others’ cigarette smoke (former & secondhand smokers).

METHODS

In the Tehran Lipid and Glucose Study, a prospective population-based cohort (n=20,069) was followed up for a median period of 14.6 years. A subset of 8,050 participants of 30 years of age and older was analyzed, with first CHD events as the study outcome. Participants were categorized as never, former, current, secondhand, and former & secondhand smokers. Data on smoking intensity (cigarette/d) were also collected. A Cox proportional hazards regression model was applied to estimate the risk of CHD, taking into account the main potential confounders.

RESULTS

The mean age of participants was 46.10 ±11.38 years, and they experienced 1,118 first CHD events (with most CHD cases in former smokers) during the follow-up period. The risk of CHD was highest in current smokers, followed in order by former & secondhand, former, and secondhand smokers (hazard ratio [HR], 1.99; 95% confidence interval [CI], 1.65 to 2.39; HR, 1.55; 95% CI, 1.15 to 2.08; HR, 1.39; 95% CI, 1.12 to 1.72; HR, 1.27; 95% CI, 1.07 to 1.51, respectively), compared to never smokers. The risk of CHD increased with smoking intensity, which has been proposed as a preferable measure of smoking, indicating a dose-response pattern.

CONCLUSIONS

The elevated risk of CHD in former & secondhand smokers was a noteworthy finding, with possible implications for health policy; however, further research is needed.

Contributions and Implications of the Tehran Lipid and Glucose Study

Tehran Lipid and Glucose Study (TLGS), an epidemiological study of non-communicable disease with 20 years follow up in a developing country in nutrition transition is a unique study in 15000 family based individuals, 3 - 75 years of age in a part of large city of Tehran. The success rate of recruitment for 20 years, intervention for lifestyle change, and thyroid, reproduction and cardiometabolic genetic studies derived from TLGS have paved suitable path towards precision medicine. In this review, baseline findings and changes of risk factors for the development of NCD including body weight, nutrition, physical activity, blood pressure, tobacco smoking, serum glucose and serum lipids as well as metabolic syndrome, chronic kidney disease, quality of life and biochemical findings in TLGS cohort have been summarized. The results of community based intervention for lifestyle change caused decreases in the prevalence of metabolic syndrome and the incidence of diabetes. It is concluded that TLGS has served as a model for other cohort studies in Iran and the region; it has helped to mobilize scientists in developing countries; it has established locally needed definitions of NCD variables; has served as a model for cohort studies in developing countries in nutrition transition with all socioeconomic constraints and has helped manpower education and development of local CVD risk scores for implementation of NCD management.