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103-650: The Trøndelag Health Study (The HUNT Study) is a cohort health study performed in the Norwegian county of Trøndelag . HUNT is considered one of the most extensive cohort studies ever conducted in any country. The HUNT Research Centre, which is responsible for collecting and providing access to the data and samples from the study, is part of the Faculty of Medicine and Health Sciences at the Norwegian University of Science and Technology (NTNU) . The study

206-515: A statistically significant increase in the incidence of lung cancer in the smoking group as compared to the non-smoking group is evidence in favor of the hypothesis. However, rare outcomes, such as lung cancer, are generally not studied with the use of a cohort study, but are rather studied with the use of a case-control study. Cohort Succession can explain most change in literature, art, intellectualism, political opinions, and phonology. Shorter term studies are commonly used in medical research as

309-582: A 10 percent to 30 percent higher risk of cardiovascular disease. Sleep disorders such as sleep-disordered breathing and insomnia , are also associated with a higher cardiometabolic risk. An estimated 50 to 70 million Americans have insomnia, sleep apnea or other chronic sleep disorders . In addition, sleep research displays differences in race and class. Short sleep and poor sleep tend to be more frequently reported in ethnic minorities than in whites. African-Americans report experiencing short durations of sleep five times more often than whites, possibly as

412-630: A 35-40 hours week. A diet high in fruits and vegetables decreases the risk of cardiovascular disease and death . A 2021 review found that plant-based diets can provide a risk reduction for CVD if a healthy plant-based diet is consumed. Unhealthy plant-based diets do not provide benefits over diets including meat. A similar meta-analysis and systematic review also looked into dietary patterns and found "that diets lower in animal foods and unhealthy plant foods, and higher in healthy plant foods are beneficial for CVD prevention". A 2018 meta-analysis of observational studies concluded that "In most countries,

515-497: A beneficial effect. A diet high in trans fatty acids is associated with higher rates of cardiovascular disease, and in 2015 the Food and Drug Administration (FDA) determined that there was 'no longer a consensus among qualified experts that partially hydrogenated oils (PHOs), which are the primary dietary source of industrially produced trans fatty acids (IP-TFA), are generally recognized as safe (GRAS) for any use in human food'. There

618-771: A cohort study when selecting participants for the cohort. RCTs may not be suitable in all cases; such as when the outcome is a negative health effect and the exposure is hypothesized to be a risk factor for the outcome. Ethical standards, and morality, would prevent the use of risk factors in RCTs. The natural or incidental exposure to these risk factors (e.g. time spent in the sun), or self-administered exposure (e.g. smoking), can be measured without subjecting participants to risk factors outside of their individual lifestyles, habits, and choices. Cohort studies can be retrospective (looking back in time, thus using existing data such as medical records or claims database) or prospective (requiring

721-595: A cohort study, the population under investigation consists of individuals who are at risk of developing a specific disease or health outcome. An example of an epidemiological question that can be answered using a cohort study is whether exposure to X (say, smoking) associates with outcome Y (say, lung cancer). For example, in 1951, the British Doctors Study was started. Using a cohort which included both smokers (the exposed group) and non-smokers (the unexposed group). The study continued through 2001. By 1956,

824-404: A defined period (e.g., are currently living, are exposed to a drug or vaccine or pollutant, or undergo a certain medical procedure). Thus a group of people who were born on a day or in a particular period, say 1948, form a birth cohort. The comparison group may be the general population from which the cohort is drawn, or it may be another cohort of persons thought to have had little or no exposure to

927-507: A form of clinical trial , or means to test a particular hypothesis of clinical importance. Such studies typically follow two groups of patients for a period of time and compare an endpoint or outcome measure between the two groups. Randomized controlled trials , or RCTs, are a superior methodology in the hierarchy of evidence, because they limit the potential for bias by randomly assigning one patient pool to an intervention and another patient pool to non-intervention (or placebo). This minimizes

1030-617: A given age , from CVD are more common and have been increasing in much of the developing world , while rates have declined in most of the developed world since the 1970s. Coronary artery disease and stroke account for 80% of CVD deaths in males and 75% of CVD deaths in females. Most cardiovascular disease affects older adults. In the United States 11% of people between 20 and 40 have CVD, while 37% between 40 and 60, 71% of people between 60 and 80, and 85% of people over 80 have CVD. The average age of death from coronary artery disease in

1133-891: A greater risk of cardiovascular disease. Policies that have resulted in increased socio-economic inequalities have been associated with greater subsequent socio-economic differences in cardiovascular disease implying a cause and effect relationship. Psychosocial factors, environmental exposures, health behaviours, and health-care access and quality contribute to socio-economic differentials in cardiovascular disease. The Commission on Social Determinants of Health recommended that more equal distributions of power, wealth, education, housing, environmental factors, nutrition, and health care were needed to address inequalities in cardiovascular disease and non-communicable diseases. Particulate matter has been studied for its short- and long-term exposure effects on cardiovascular disease . Currently, airborne particles under 2.5 micrometers in diameter (PM 2.5 ) are

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1236-508: A male with diabetes. Women who have high blood pressure and had complications in their pregnancy have three times the risk of developing cardiovascular disease compared to women with normal blood pressure who had no complications in pregnancy. Coronary heart diseases are 2 to 5 times more common among middle-aged men than women. In a study done by the World Health Organization , sex contributes to approximately 40% of

1339-450: A misnomer as the methodological principles of historical cohort studies and prospective studies are the same. A nested case-control study is a case control nested inside of a cohort study. The procedure begins like a normal cohort study, however, as participants develop the outcome of interest they are selected as cases. Once the cases are identified, controls are selected and matched to each case. The process for selecting and matching cases

1442-838: A number of Harvard graduates from ca. 1950.77, the Whitehall Study tracking 10,308 British civil servants, and the Caerphilly Heart Disease Study , which since 1979 has studied a representative sample of 2,512 men, drawn from the Welsh town of Caerphilly. The ASPREE-XT study is designed to determine whether there are long-lasting effects of an average of four–five years of treatment with daily low-dose aspirin, with outcome measures including cancer mortality. As of September 2018, there were 16,703 ASPREE-XT participants in Australia. It has been proposed that

1545-451: A reduction in cardiovascular events. A 2015 meta-analysis of observational studies however did not find a convincing association between saturated fat intake and cardiovascular disease. Variation in what is used as a substitute for saturated fat may explain some differences in findings. The benefit from replacement with polyunsaturated fats appears greatest, while replacement of saturated fats with carbohydrates does not appear to have

1648-503: A result of social and environmental factors. Black children and children living in disadvantaged neighborhoods have much higher rates of sleep apnea. Cardiovascular disease has a greater impact on low- and middle-income countries compared to those with higher income. Although data on the social patterns of cardiovascular disease in low- and middle-income countries is limited, reports from high-income countries consistently demonstrate that low educational status or income are associated with

1751-432: A risk of death as never smokers. Insufficient physical activity (defined as less than 5 x 30 minutes of moderate activity per week, or less than 3 x 20 minutes of vigorous activity per week) is currently the fourth leading risk factor for mortality worldwide. In 2008, 31.3% of adults aged 15 or older (28.2% men and 34.4% women) were insufficiently physically active. The risk of ischemic heart disease and diabetes mellitus

1854-405: A similar outcome or end-point. Once the cohort is identified, we further learn the commonalities among the associated patients and obtain meaningful cohort representations. These AI-derived cohorts not only enhance the ability to evaluate new patients but also hold significant potential to accelerate medical research and discovery. Cardiovascular disease Cardiovascular disease ( CVD )

1957-437: A small amount compared to usual care. However, there was some uncertainty as to whether providing these scores had any effect on cardiovascular disease events. It is unclear whether or not dental care in those with periodontitis affects their risk of cardiovascular disease. According to a 2021 WHO study, working 55+ hours a week raises the risk of stroke by 35% and the risk of dying from heart conditions by 17%, when compared to

2060-461: A small effect. Age is the most important risk factor in developing cardiovascular or heart diseases, with approximately a tripling of risk with each decade of life. Coronary fatty streaks can begin to form in adolescence. It is estimated that 82 percent of people who die of coronary heart disease are 65 and older. Simultaneously, the risk of stroke doubles every decade after age 55. Multiple explanations are proposed to explain why age increases

2163-1072: A usual annual basis. Examples include the US Panel Study of Income Dynamics (since 1968), the German Socio-Economic Panel (since 1984), the British Household Panel Survey (since 1991) and (since 2009) its successor Understanding Society: the UK Household Longitudinal Study , the Household, Income and Labour Dynamics in Australia Survey (since 2001) and the European Community Household Panel (1994–2001). For an example in business analysis, see cohort analysis . Conventionally, cohort studies require manual definitions of

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2266-709: A vegan diet is associated with a more favourable cardio-metabolic profile compared to an omnivorous diet." Evidence suggests that the Mediterranean diet may improve cardiovascular outcomes. There is also evidence that a Mediterranean diet may be more effective than a low-fat diet in bringing about long-term changes to cardiovascular risk factors (e.g., lower cholesterol level and blood pressure ). The DASH diet (high in nuts, fish, fruits and vegetables, and low in sweets, red meat and fat) has been shown to reduce blood pressure, lower total and low density lipoprotein cholesterol and improve metabolic syndrome ; but

2369-516: A wider range of subjects, and more data collected for each participant. Overall participation in HUNT2 was roughly 74,000 people (70% of the overall population). 64% of the HUNT2 (Young and adult) participants also participated in the HUNT1 survey. Clinical monitoring, data processing and quality control was performed after data collection was completed, and from autumn 1998 data files have been available to

2472-409: Is also beneficial. Treating people who have strep throat with antibiotics can decrease the risk of rheumatic heart disease. The use of aspirin in people who are otherwise healthy is of unclear benefit. Cardiovascular diseases are the leading cause of death worldwide except Africa. Together CVD resulted in 17.9 million deaths (32.1%) in 2015, up from 12.3 million (25.8%) in 1990. Deaths, at

2575-1214: Is also linked to carotid artery thickening and increased risk of acute myocardial infarction. Existing cardiovascular disease or a previous cardiovascular event, such as a heart attack or stroke, is the strongest predictor of a future cardiovascular event. Age, sex, smoking, blood pressure, blood lipids and diabetes are important predictors of future cardiovascular disease in people who are not known to have cardiovascular disease. These measures, and sometimes others, may be combined into composite risk scores to estimate an individual's future risk of cardiovascular disease. Numerous risk scores exist although their respective merits are debated. Other diagnostic tests and biomarkers remain under evaluation but currently these lack clear-cut evidence to support their routine use. They include family history, coronary artery calcification score, high sensitivity C-reactive protein (hs-CRP), ankle–brachial pressure index , lipoprotein subclasses and particle concentration, lipoprotein(a), apolipoproteins A-I and B, fibrinogen , white blood cell count, homocysteine , N-terminal pro B-type natriuretic peptide (NT-proBNP), and markers of kidney function. High blood phosphorus

2678-494: Is also linked to an increased risk. There is evidence that mental health problems, in particular depression and traumatic stress, is linked to cardiovascular diseases. Whereas mental health problems are known to be associated with risk factors for cardiovascular diseases such as smoking, poor diet, and a sedentary lifestyle, these factors alone do not explain the increased risk of cardiovascular diseases seen in depression, stress, and anxiety. Moreover, posttraumatic stress disorder

2781-488: Is any disease involving the heart or blood vessels . CVDs constitute a class of diseases that includes: coronary artery diseases (e.g. angina , heart attack ), heart failure , hypertensive heart disease , rheumatic heart disease , cardiomyopathy , arrhythmia , congenital heart disease , valvular heart disease , carditis , aortic aneurysms , peripheral artery disease , thromboembolic disease , and venous thrombosis . The underlying mechanisms vary depending on

2884-422: Is associated with heart disease. Associations also exist for exposure to arsenic , benzopyrenes , lead , dynamite , carbon disulphide , carbon monoxide , metalworking fluids and occupational exposure to tobacco smoke . Working with the electrolytic production of aluminium or the production of paper when the sulphate pulping process is used is associated with heart disease. An association

2987-514: Is being electrolytically produced, is associated with stroke . As of 2017, evidence suggests that certain leukemia -associated mutations in blood cells may also lead to increased risk of cardiovascular disease. Several large-scale research projects looking at human genetic data have found a robust link between the presence of these mutations, a condition known as clonal hematopoiesis , and cardiovascular disease-related incidents and mortality. Radiation treatments (RT) for cancer can increase

3090-411: Is complex, and may depend on the amount of alcohol consumed. There is a direct relationship between high levels of drinking alcohol and cardiovascular disease. Drinking at low levels without episodes of heavy drinking may be associated with a reduced risk of cardiovascular disease, but there is evidence that associations between moderate alcohol consumption and protection from stroke are non-causal. At

3193-452: Is conflicting evidence concerning whether dietary supplements of omega-3 fatty acids (a type of polyunsaturated essential fatty acid) added to diet improve cardiovascular risk. The benefits of recommending a low-salt diet in people with high or normal blood pressure are not clear. In those with heart failure, after one study was left out, the rest of the trials show a trend to benefit. Another review of dietary salt concluded that there

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3296-435: Is disputed. The World Health Organization attributes approximately 1.7 million deaths worldwide to low fruit and vegetable consumption. Frequent consumption of high-energy foods, such as processed foods that are high in fats and sugars, promotes obesity and may increase cardiovascular risk. The amount of dietary salt consumed may also be an important determinant of blood pressure levels and overall cardiovascular risk. There

3399-543: Is documented as increasing cardiovascular risk in both adults and teens. Recommendations suggest that infants typically need 12 or more hours of sleep per day, adolescents at least eight or nine hours, and adults seven or eight. About one-third of adult Americans get less than the recommended seven hours of sleep per night, and in a study of teenagers, just 2.2 percent of those studied got enough sleep, many of whom did not get good quality sleep. Studies have shown that short sleepers getting less than seven hours sleep per night have

3502-488: Is estimated to account for approximately 13% of CVD deaths, while tobacco accounts for 9%, diabetes 6%, lack of exercise 6%, and obesity 5%. Rheumatic heart disease may follow untreated strep throat . It is estimated that up to 90% of CVD may be preventable. Prevention of CVD involves improving risk factors through: healthy eating , exercise, avoidance of tobacco smoke and limiting alcohol intake. Treating risk factors, such as high blood pressure, blood lipids and diabetes

3605-412: Is evidence that higher consumption of sugar is associated with higher blood pressure and unfavorable blood lipids, and sugar intake also increases the risk of diabetes mellitus. High consumption of processed meats is associated with an increased risk of cardiovascular disease, possibly in part due to increased dietary salt intake. The relationship between alcohol consumption and cardiovascular disease

3708-535: Is identical to a normal case control study. An example of a nested case-control study is Inflammatory markers and the risk of coronary heart disease in men and women , which was a case control analyses extracted from the Framingham Heart Study cohort. Nested case-controls have the advantage of reducing the number of participants that require details follow up or diagnostic testing to assess outcome or exposure status. However, this will also reduce

3811-597: Is inconclusive. Additionally echocardiography , myocardial perfusion imaging , and cardiac stress testing is not recommended in those at low risk who do not have symptoms. Some biomarkers may add to conventional cardiovascular risk factors in predicting the risk of future cardiovascular disease; however, the value of some biomarkers is questionable. Ankle-brachial index (ABI), high-sensitivity C-reactive protein (hsCRP), and coronary artery calcium , are also of unclear benefit in those without symptoms as of 2018. The NIH recommends lipid testing in children beginning at

3914-490: Is independently associated with increased risk for incident coronary heart disease, even after adjusting for depression and other covariates. Little is known about the relationship between work and cardiovascular disease, but links have been established between certain toxins, extreme heat and cold, exposure to tobacco smoke, and mental health concerns such as stress and depression. A 2015 SBU-report looking at non-chemical factors found an association for those: Specifically

4017-509: Is moderate quality evidence that reducing saturated fat intake for at least two years reduces the risk of cardiovascular disease. High trans-fat intake has adverse effects on blood lipids and circulating inflammatory markers, and elimination of trans-fat from diets has been widely advocated. In 2018 the World Health Organization estimated that trans fats were the cause of more than half a million deaths per year. There

4120-543: Is reduced by almost a third in adults who participate in 150 minutes of moderate physical activity each week (or equivalent). In addition, physical activity assists weight loss and improves blood glucose control, blood pressure, lipid profile and insulin sensitivity. These effects may, at least in part, explain its cardiovascular benefits. High dietary intakes of saturated fat, trans-fats and salt, and low intake of fruits, vegetables and fish are linked to cardiovascular risk, although whether all these associations indicate causes

4223-452: Is some evidence that interventions aiming to reduce more than one cardiovascular risk factor may have beneficial effects on blood pressure, body mass index and waist circumference; however, evidence was limited and the authors were unable to draw firm conclusions on the effects on cardiovascular events and mortality. There is additional evidence to suggest that providing people with a cardiovascular disease risk score may reduce risk factors by

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4326-418: Is still ongoing. HUNT2 was more extensive than HUNT1, because all residents 13 years and older were invited. HUNT2 was divided into Adult- and Young-HUNT. Young-HUNT1 involved the 13- to 19-year-old age group and Adult-HUNT (HUNT2) involved participants 20 years and older. Overall participation in HUNT2 was roughly 75,000 people (70% of the overall population). 61% of the HUNT2 participants also participated in

4429-467: Is strong evidence that high dietary salt intake increases blood pressure and worsens hypertension, and that it increases the number of cardiovascular disease events; both as a result of the increased blood pressure and probably through other mechanisms. Moderate evidence was found that high salt intake increases cardiovascular mortality; and some evidence was found for an increase in overall mortality, strokes, and left ventricular hypertrophy . Overall,

4532-582: Is that it can help determine risk factors for contracting a new disease because it is a longitudinal observation of the individual through time, and the collection of data at regular intervals, so recall error is reduced. However, cohort studies are expensive to conduct, are sensitive to attrition and take a long follow-up time to generate useful data. Nevertheless, the results that are obtained from long-term cohort studies are of substantially superior quality to those obtained from retrospective/cross-sectional studies. Prospective cohort studies are considered to yield

4635-619: Is the Nurses' Health Study . Starting in 1976, it is tracking over 120,000 nurses and has been analyzed for many different conditions and outcomes. The largest cohort study in Africa is the Birth to Twenty Study, which began in 1990 and tracks a cohort of over 3,000 children born in the weeks following Nelson Mandela 's release from prison. Other famous examples are the Grant Study tracking

4738-531: Is the adolescent part of the HUNT Study. Participants are aged 13–19 years. The main topics in Young-HUNT have been asthma and allergies, mental health and quality of life, eating disorders and psychosomatic disorders with special emphasis on headaches. Information about tobacco, alcohol habits, physical activity, health, stages of puberty and literacy problems have also been gathered. Young-HUNT1 (1995–97)

4841-407: Is the most life-threatening of the diabetic complications and diabetics are two- to four-fold more likely to die of cardiovascular-related causes than nondiabetics. Screening ECGs (either at rest or with exercise) are not recommended in those without symptoms who are at low risk. This includes those who are young without risk factors. In those at higher risk the evidence for screening with ECGs

4944-863: The Framingham Heart Study and the National Child Development Study (NCDS), the most widely researched of the British birth cohort studies . Key findings of NCDS and a detailed profile of the study appear in the International Journal of Epidemiology . The Dunedin Multidisciplinary Health and Development Study has been studying the thousand people born in Dunedin , New Zealand, in 1972–1973. The subjects are interviewed regularly, with Phase (age) 52 starting in 2024. The largest cohort study in women

5047-640: The coronary arteries . Cardiovascular disease in a person's parents increases their risk by ~3 fold, and genetics is an important risk factor for cardiovascular diseases. Genetic cardiovascular disease can occur either as a consequence of single variant (Mendelian) or polygenic influences. There are more than 40 inherited cardiovascular disease that can be traced to a single disease-causing DNA variant, although these conditions are rare. Most common cardiovascular diseases are non-Mendelian and are thought to be due to hundreds or thousands of genetic variants (known as single nucleotide polymorphisms), each associated with

5150-599: The HUNT Research Center decided to stop all personal attendance in the follow-up projects under HUNT4 for the time being, due to the risk of infection by the coronavirus . As the COVID-19 situation in Norway is mostly under control and the infection rate is low, some of the projects have later (June 2020–) permitted personal attendance. These were also additional projects in connection with HUNT4: Young-HUNT

5253-844: The HUNT study, were sent a short in January 2009 were sent a short questionnaire with some key health and lifestyle variables, to study characteristics of non-responders. Measurements of height, weight, waist circumference, hip width, blood pressure and pulse were collected, as well as bone mass and spirometry measurements. All adults were interviewed about occupation (occupational classification) and health related occupational exposure, and women were interviewed about issues related to pregnancy, childbirth and breastfeeding. Biological material collected in HUNT3 includes blood (5 glasses for different uses) and urine test (fresh or frozen) for adults, and cheek swabs for

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5356-466: The HUNT1 survey. There were several additional studies in HUNT2, including spirometry and measuring of bone density. HUNT2 was a follow-up of the HUNT1: the questions and comments regarding high blood pressure, diabetes and quality of life were identical or very similar to the questions in HUNT1. HUNT2 was a much larger study, with a larger age range (from 13 years upwards, see section «Young-HUNT1» below),

5459-619: The Regional Committee for Medical Research Ethics ( REK). If data from sources that are not regulated by the Health Research Act are used, the project must also be reported to the Privacy Ombudsman for Research (NSD). The project manager should be familiar with the HUNT database and select the relevant variables. HUNT1, the first of the major health surveys, was conducted from 1984 to 1986, to establish

5562-420: The age of 2 if there is a family history of heart disease or lipid problems. It is hoped that early testing will improve lifestyle factors in those at risk such as diet and exercise. Screening and selection for primary prevention interventions has traditionally been done through absolute risk using a variety of scores (ex. Framingham or Reynolds risk scores). This stratification has separated people who receive

5665-542: The award is to stimulate interest and the work for public health and social conditions that have significance for this. The HUNT Research Centre is divided into a biological repository ( HUNT Biobank ) and a database made up by more than 5,500 variables (HUNT Databank). Data from the HUNT Study are available to institutions and researchers who satisfy some basic requirements, whether affiliated in Norway or abroad. Any institution with research skills can apply for permission to analyze HUNT data. Each project must be approved by

5768-441: The beneficial and harmful effects of different methods of contraception. This study has provided a large amount of information on the efficacy and safety of contraceptive methods, and in particular oral contraceptives (OCs), diaphragms and intrauterine device (IUDs). In a historical cohort study the data concerning exposure and occurrence of a disease, births, a political attitude or any other categorical variable are collected after

5871-498: The chance that the incidence of confounding variables will differ between the two groups. Nevertheless, it is sometimes not practical or ethical to perform RCTs to answer a clinical question. To take our example, if we already had reasonable evidence that smoking causes lung cancer then persuading a pool of non-smokers to take up smoking in order to test this hypothesis would generally be considered unethical. Two examples of cohort studies that have been going on for more than 50 years are

5974-560: The chest were collected. HUNT1 was the first health survey in Nord-Trøndelag, and consisted mainly of four sub-studies whose subjects were blood pressure, diabetes, lung disease and quality of life. The purpose of this study was to determine the prevalence of hypertension and diabetes, and to evaluate the quality of life in people with high blood pressure, people with diabetes and people with tuberculosis. Non-fasting blood glucose levels were measured in all participants over 40 years. If

6077-442: The collection of new data). Retrospective cohort studies restrict the investigators' ability to reduce confounding and bias because collected information is restricted to data that already exists. There are advantages to this design, however, as retrospective studies are much cheaper and faster because the data has already been collected and stored. A cohort is a group of people who share a common characteristic or experience within

6180-429: The common characteristics, which are time-consuming and labor-intensive, demanding extensive domain expertise. To address these limitations, researchers have increasingly explored the integration of AI technologies to automate the identification of cohorts with their definitions. For example, in healthcare, we can identify patients with a certain combination of feature conditions as a specific cohort, typically resulting in

6283-859: The developed world is around 80, while it is around 68 in the developing world. CVD is typically diagnosed seven to ten years earlier in men than in women. There are many cardiovascular diseases involving the blood vessels. They are known as vascular diseases . There are also many cardiovascular diseases that involve the heart. There are many risk factors for heart diseases: age, sex, tobacco use, physical inactivity, non-alcoholic fatty liver disease , excessive alcohol consumption, unhealthy diet, obesity, genetic predisposition and family history of cardiovascular disease, raised blood pressure ( hypertension ), raised blood sugar ( diabetes mellitus ), raised blood cholesterol ( hyperlipidemia ), undiagnosed celiac disease , psychosocial factors, poverty and low educational status, air pollution , and poor sleep . While

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6386-539: The disease under investigation. The study groups follow a group of people who do not have the disease for a period of time and see who develops the disease (new incidence). The cohort cannot therefore be defined as a group of people who already have the disease. Prospective (longitudinal) cohort studies between exposure and disease strongly aid in studying causal associations, though distinguishing true causality usually requires further corroboration from further experimental trials. The advantage of prospective cohort study data

6489-426: The disease. It is estimated that dietary risk factors are associated with 53% of CVD deaths. Coronary artery disease, stroke, and peripheral artery disease involve atherosclerosis . This may be caused by high blood pressure , smoking , diabetes mellitus , lack of exercise , obesity , high blood cholesterol , poor diet, excessive alcohol consumption, and poor sleep , among other things. High blood pressure

6592-589: The events have taken place, and the subjects (those exposed and unexposed to the agent under study) are assembled from existing records or health care registers. A " prospective cohort " defines the groups before the study is done, while historical studies, which are sometimes referred to as " retrospective cohort ", define the grouping after the data is collected. Examples of a retrospective cohort are Long-Term Mortality after Gastric Bypass Surgery and The Lothian Birth Cohort Studies . Although historical studies are sometimes referred to as retrospective study, it

6695-446: The existing ASPREE-XT study could provide a platform for a future multigenerational research study. The diagram indicates the starting point and direction of cohort and case-control studies. In case-control studies the analysis proceeds from documented disease and investigations are made to arrive at the possible causes of the disease. In cohort studies the assessment starts with the putative cause of disease, and observations are made of

6798-496: The fall of 2019, HUNT was expanded to include the entire county. As of 2017, 170 ph.ds and about 1,700 scientific articles were based on the HUNT material. New articles published in 2017 alone were 110. In 2017 The HUNT Study was awarded the Karl Evang Prize. This Norwegian prize was established in 1981, as a tribute to the former Director of Health, Karl Evang , for his social-medical pioneering efforts. The aim of

6901-482: The female lipid metabolism toward a more atherogenic form by decreasing the HDL cholesterol level while increasing LDL and total cholesterol levels. Among men and women, there are differences in body weight, height, body fat distribution, heart rate, stroke volume, and arterial compliance. In the very elderly, age-related large artery pulsatility and stiffness are more pronounced among women than men. This may be caused by

7004-466: The fundamental designs of epidemiology which are used in research in the fields of medicine , pharmacy , nursing , psychology , social science , and in any field reliant on 'difficult to reach' answers that are based on evidence ( statistics ). In medicine for instance, while clinical trials are used primarily for assessing the safety of newly developed pharmaceuticals before they are approved for sale, epidemiological analysis on how risk factors affect

7107-522: The health history of 75,000 people. All residents in Nord-Trøndelag, 20 years and older, were invited to the study, and 74,599 people, 20 years and older, participated (88.1% of the county's population). The participants filled out two questionnaires. The main objective was to investigate the prevalence of hypertension and diabetes in the population, and to evaluate the quality of treatment for blood pressure patients, people with diabetes, and people with tuberculosis. Blood pressure, height, weight, and X-rays of

7210-417: The incidence of diseases is often used to identify the causes of diseases in the first place, and to help provide pre-clinical justification for the plausibility of protective factors (treatments). Cohort studies differ from clinical trials in that no intervention, treatment, or exposure is administered to participants in a cohort design; and no control group is defined. Rather, cohort studies are largely about

7313-432: The incidence rate of the disease or outcome in question. Regression analysis can then be used to evaluate the extent to which the exposure or treatment variable contributes to the incidence of the disease, while accounting for other variables that may be at play. Double-blind randomized controlled trials (RCTs) are generally considered superior methodology in the hierarchy of evidence in treatment, because they allow for

7416-528: The individual contribution of each risk factor varies between different communities or ethnic groups the overall contribution of these risk factors is very consistent. Some of these risk factors, such as age, sex or family history/genetic predisposition, are immutable; however, many important cardiovascular risk factors are modifiable by lifestyle change, social change, drug treatment (for example prevention of hypertension, hyperlipidemia, and diabetes). People with obesity are at increased risk of atherosclerosis of

7519-464: The intermediate and low risk groups. As a result, future preventative screening appears to shift toward applying prevention according to randomized trial results of each intervention rather than large-scale risk assessment. Up to 90% of cardiovascular disease may be preventable if established risk factors are avoided. Currently practised measures to prevent cardiovascular disease include: Most guidelines recommend combining preventive strategies. There

7622-432: The life histories of segments of populations and the individual people who constitute these segments. Exposures or protective factors are identified as preexisting characteristics of participants. The study is controlled by including other common characteristics of the cohort in the statistical analysis. Both exposure/treatment and control variables are measured at baseline. Participants are then followed over time to observe

7725-425: The lifestyle interventions (generally lower and intermediate risk) from the medication (higher risk). The number and variety of risk scores available for use has multiplied, but their efficacy according to a 2016 review was unclear due to lack of external validation or impact analysis. Risk stratification models often lack sensitivity for population groups and do not account for the large number of negative events among

7828-616: The long-term benefits have been questioned. A high- fiber diet is associated with lower risks of cardiovascular disease. Worldwide, dietary guidelines recommend a reduction in saturated fat , and although the role of dietary fat in cardiovascular disease is complex and controversial there is a long-standing consensus that replacing saturated fat with unsaturated fat in the diet is sound medical advice. Total fat intake has not been found to be associated with cardiovascular risk. A 2020 systematic review found moderate quality evidence that reducing saturated fat intake for at least 2 years caused

7931-461: The loss of arterial elasticity and reduced arterial compliance and may subsequently lead to coronary artery disease. Men are at greater risk of heart disease than pre-menopausal women. Once past menopause , it has been argued that a woman's risk is similar to a man's although more recent data from the WHO and UN disputes this. If a female has diabetes, she is more likely to develop heart disease than

8034-600: The major focus, in which gradients are used to determine CVD risk. Overall, long-term PM exposure increased rate of atherosclerosis and inflammation. In regards to short-term exposure (2 hours), every 25 μg/m of PM 2.5 resulted in a 48% increase of CVD mortality risk. In addition, after only 5 days of exposure, a rise in systolic (2.8 mmHg) and diastolic (2.7 mmHg) blood pressure occurred for every 10.5 μg/m of PM 2.5 . Other research has implicated PM 2.5 in irregular heart rhythm, reduced heart rate variability (decreased vagal tone), and most notably heart failure. PM 2.5

8137-510: The major precursor of cardiovascular disease, begins in childhood. The Pathobiological Determinants of Atherosclerosis in Youth (PDAY) study demonstrated that intimal lesions appear in all the aortas and more than half of the right coronary arteries of youths aged 7–9 years. Obesity and diabetes mellitus are linked to cardiovascular disease, as are a history of chronic kidney disease and hypercholesterolaemia . In fact, cardiovascular disease

8240-572: The most control over other variables that could affect the outcome, and the randomization and blinding processes reduce bias in the study design. This minimizes the chance that results will be influenced by confounding variables, particularly ones that are unknown. However, educated hypotheses based on prior research and background knowledge are used to select variables to be included in the regression model for cohort studies, and statistical methods can be used to identify and account for potential confounders from these variables. Bias can also be mitigated in

8343-417: The most reliable results in observational epidemiology. They enable a wide range of exposure-disease associations to be studied. Some cohort studies track groups of children from their birth, and record a wide range of information (exposures) about them. The value of a cohort study depends on the researchers' capacity to stay in touch with all members of the cohort. Some studies have continued for decades. In

8446-569: The occurrence of disease relative to the hypothesized causal agent . A current cohort study represents a true prospective study where the data concerning exposure are assembled prior to the occurrence of the fact to be studied, for instance a disease. An example of a current cohort study is the Oxford Family Planning Association Study in the United Kingdom, which aimed to provide a balanced view of

8549-418: The population level, the health risks of drinking alcohol exceed any potential benefits. Untreated celiac disease can cause the development of many types of cardiovascular diseases, most of which improve or resolve with a gluten-free diet and intestinal healing. However, delays in recognition and diagnosis of celiac disease can cause irreversible heart damage. A lack of good sleep, in amount or quality,

8652-410: The power of the study, when compared to larger cohort the study population is drawn from. Panel surveys are another important sub-type of longitudinal study . They differ from cohort studies by starting with representative cross-sectional samples, rather than cohorts defined by an event. Household panels draw representative samples of households and survey them, following all individuals through time on

8755-600: The relative importance of genetic and environmental causes of several diseases. HUNT3 was designed in the same manner as HUNT2, but included more themes. The data was collected through questionnaires and clinical examinations. In addition genetic material, blood, urine (adults) and cell samples from the mouth (youth) were stored in the HUNT biobank. HUNT3 used the slogan "A time for better health". All residents in Nord-Trøndelag, 13 years and older, were again invited to participate. (See section «Young-HUNT3» for persons 13–19 years old) Approximately 105,000 people were invited, and data

8858-415: The research community. Besides the questionnaire data and clinical measurements, a venous blood sample was taken from all participants 20 years or older, and after preliminary analysis, both serum samples and whole blood samples were frozen. These are today (2020) stored at minus 70 °C. Blood samples are a source of genetic information, and thus have great potential for research in genetic epidemiology, or

8961-466: The results of this investigation indicated diabetes, the participant was offered a clinical examination as well. Blood samples were not taken in this study. A comprehensive dropout study was also conducted. At present (2020), the database is a valuable resource for epidemiological research, both in cardiovascular diseases , diabetes and quality of life. Studies of cancer and public health have also been performed on this material, and research from HUNT1 data

9064-443: The risk of stroke was also increased by exposure to ionizing radiation. Hypertension develops more often in those who experience job strain and who have shift-work. Differences between women and men in risk are small, however men risk having and dying of heart attacks or stroke twice as often as women during working life. A 2017 SBU report found evidence that workplace exposure to silica dust , engine exhaust or welding fumes

9167-423: The risk of cardiovascular/heart diseases. One of them relates to serum cholesterol level. In most populations, the serum total cholesterol level increases as age increases. In men, this increase levels off around age 45 to 50 years. In women, the increase continues sharply until age 60 to 65 years. Aging is also associated with changes in the mechanical and structural properties of the vascular wall, which leads to

9270-955: The risk of heart disease and death, as observed in breast cancer therapy. Therapeutic radiation increases the risk of a subsequent heart attack or stroke by 1.5 to 4 times; the increase depends on the dose strength, volume, and location. Use of concomitant chemotherapy, e.g. anthracyclines, is an aggravating risk factor. The occurrence rate of RT induced cardiovascular disease is estimated between 10% and 30%. Side-effects from radiation therapy for cardiovascular diseases have been termed radiation-induced heart disease or radiation-induced cardiovascular disease . Symptoms are dose-dependent and include cardiomyopathy , myocardial fibrosis , valvular heart disease , coronary artery disease , heart arrhythmia and peripheral artery disease . Radiation-induced fibrosis, vascular cell damage and oxidative stress can lead to these and other late side-effect symptoms. Population-based studies show that atherosclerosis,

9373-420: The study provided convincing proof of the association between smoking and the incidence of lung cancer. In a cohort study, the groups are matched in terms of many other variables such as economic status and other health status so that the variable being assessed, the independent variable (in this case, smoking) can be isolated as the cause of the dependent variable (in this case, lung cancer). In this example,

9476-414: The substance under investigation, but otherwise similar. Alternatively, subgroups within the cohort may be compared with each other. In medicine, a cohort study is often undertaken to obtain evidence to try to refute the existence of a suspected association between cause and effect; failure to refute a hypothesis often strengthens confidence in it. Crucially, the cohort is identified before the appearance of

9579-405: The survey Young-HUNT4. For the first time the inhabitants of the southern part of the county, Sør-Trøndelag, were invited to answer a questionnaire in 2019. As the counties of Nord- and Sør-Trøndelag merged in 2018, the study was from then on known as The Trøndelag Health Study, but kept the acronym HUNT. Several additional projects were implemented in connection with HUNT4: On March 12, 2020,

9682-462: The surveys and in several national health- and other registers covering the total population. The HUNT Study includes data from questionnaires, interviews, clinical measurements and biological samples (blood and urine). The questionnaires include questions on socioeconomic conditions, health related behaviours, symptoms, illnesses and diseases. From the beginning, in 1984, every citizen of Nord-Trøndelag being 20 years or older, have been invited to all

9785-473: The surveys for adults, and more than 80% of the population (n=130,000) participated. The population of Nord-Trøndelag was both homogeneous and stable, making it especially suited for epidemiological genetic research. HUNT contains a unique database of personal and family medical histories collected during four surveys (HUNT1, 2, 3 and 4) since 1984. On January 1, 2018, the two counties Sør-Trøndelag and Nord-Trøndelag were merged into one county: Trøndelag, and from

9888-592: The variation in sex ratios of coronary heart disease mortality. Another study reports similar results finding that sex differences explains nearly half the risk associated with cardiovascular diseases One of the proposed explanations for sex differences in cardiovascular diseases is hormonal difference. Among women, estrogen is the predominant sex hormone. Estrogen may have protective effects on glucose metabolism and hemostatic system, and may have direct effect in improving endothelial cell function. The production of estrogen decreases after menopause, and this may change

9991-406: The women's smaller body size and arterial dimensions which are independent of menopause. Cigarettes are the major form of smoked tobacco. Risks to health from tobacco use result not only from direct consumption of tobacco, but also from exposure to second-hand smoke. Approximately 10% of cardiovascular disease is attributed to smoking; however, people who quit smoking by age 30 have almost as low

10094-478: The youth. As many as 75% of the HUNT3 participants were also screened in the HUNT2 survey. Collection of biological material was the largest investment in HUNT3, resulting in the establishment of a state-of-the-art biobank, HUNT Biobank, with storage facilities that ensure availability of the biomaterial for research decades ahead. HUNT4 was carried out in 2017–2019. 56,044 people from Nord-Trøndelag county participated. Adolescents (13–19) were invited to participate in

10197-459: Was also found between heart disease and exposure to compounds which are no longer permitted in certain work environments, such as phenoxy acids containing TCDD (dioxin) or asbestos . Workplace exposure to silica dust or asbestos is also associated with pulmonary heart disease . There is evidence that workplace exposure to lead, carbon disulphide, phenoxyacids containing TCDD, as well as working in an environment where aluminum

10300-445: Was collected from roughly 60,000. The overall attendance rate was about 56%, with variations depending on age. The survey used 18 different questionnaires based on the survey in HUNT2. Participants filled out a common form called questionnaire 1 (Q1) and were given questionnaire 2 (Q2) depending on age and gender. In addition, participants could be given one or more of questionnaire 3 (Q3). In addition to this, all adults who had not met in

10403-531: Was conducted as part of HUNT2. 9141 adolescents participated (90% response rate). was a follow-up study of Young-HUNT1, 2400 students participated in both studies (77% of the invited). Young-HUNT3 (2006–08) was a new cross-sectional study as part of HUNT3. 8677 adolescents participated (87% response rate). Data collection included self-reported questionnaires, structured interviews, clinical measurements and, in Young-HUNT3, buccal smears. In Young-HUNT3 there

10506-711: Was one form similar to the one used in Young-HUNT1. People in the Young-HUNT survey had height, weight, blood pressure, pulse, and spirometry measured. The Young-HUNT4 Survey (2017-2019) was again a new wave of data gathering concurrent with the HUNT4 Survey. 8066 participants aged 13–19 filled in the questionnaire on tablet computers . In addition, they participated in clinical measurement and an interview, and saliva samples were collected. Most adolescents were recruited through schools, and participated while at school. Cohort study Cohort studies represent one of

10609-500: Was primarily set up to address arterial hypertension , diabetes , screening of tuberculosis , and quality of life . However, the scope has expanded over time. The population based surveys now contribute to important knowledge regarding health related lifestyle, prevalence and incidence of somatic and mental illness and disease, health determinants , and associations between disease phenotypes and genotypes . Participants may be linked in families and followed up longitudinally between

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