ABSTRACT
In the late 1990s the non-communicable diseases were becoming increasingly more prevalent and a significant proportion of evidence in this regard had originated from industrialized "Western" countries. This had led to a landscape where most national and local health decisions regarding non-communicable diseases [NCDs] were informed by data generated elsewhere. Iran, as a large country in the Middle East was no exception and was going through significant population growth and urban development at the time. An initiative by the Iranian National Scientific Research Council funded an idea that was aimed at delineating the local epidemiology of NCDs and their risk factors in a manner that was unprecedented. The result was Tehran Lipid and Glucose Study [TLGS], the first and longest running cohort of its sort in Iran. Initial data out of TLGS reported the characteristics of 15005 people aged over 3 years in a representative population of Tehranians. Additionally, distribution and prevalence of cardiovascular risk factors among the study population were characterized. This population was selected through a multistage stratified cluster random sampling technique from the population of district 13 in Tehran. In addition, TLGS gave rise to a great deal of important and highly effective initial findings on national cut-off points for various variables, information about nutrition, hypertension, dyslipoproteinemia, and metabolic syndrome. TLGS also generated information about metabolic health indicators among children and adolescents. Here we present a brief overview of rationale, design, and initial findings of TLGS
ABSTRACT
Context: this review summarizes key findings of the Tehran thyroid study [TTS], a large scale community-based study with approximately a two decade follow-up, about the incidence, prevalence, and natural course of thyroid disorders as well as associations between thyroid diseases and metabolic syndrome [MetS], dysglycemia, and cardiovascular disease [CVD]
Evidence Acquisition: pubMed, Scopus, and Web of Science databases, and the library of Research Institute for Endocrine Sciences were used to search for TTS articles. Articles were subdivided based on the fields of prevalence, incidence and natural course, and associations of thyroid function with the incident hypertension [HTN], MetS and CVDs
Results: the 2.5th and 97.5th percentiles of serum thyrotropin [TSH] were 0.32 and 5.06 mU/L, respectively. Estimated reference intervals [2.5th and 97.5th percentiles] for thyroid peroxidase antibody [TPOAb] levels were 1.5 - 32.8 and 2.1 - 35 IU/mL in men and women, respectively. Euthyroid persistencywas93.24% during6years. There was a negative association between free thyroxine [FT4] levels and insulin resistance. Decreasing FT4 values over time would predict MetS in euthyroid and subclinical hypothyroid subjects [TSH < 10 mU/L]. The incidence of thyroid disorders in patients with diabetes, pre-diabetes and healthy controls was 14, 18, and 21 per 1000 person-years, respectively, indicating significantly lower incidence in individuals with diabetes compared to healthy controls. Serum FT4 within the reference range was positively associated with all blood pressure [BP] measures in the total population and in men; however, serum TSH was positively associated with only systolic BP [SBP], diastolic BP [DBP] and mean arterial pressure of men. No associations were found between various states of thyroid function and prevalence and incidence of CVD
Conclusions: a well designed cohort study aimed to investigate the gap in knowledge regarding thyroid disorders can generate many hypotheses to be examined in randomized controlled trials
ABSTRACT
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