Chapter 7 summarized

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The text describes the period of luxury and indulgence in America after World War II and how heart disease emerged as an epidemic despite the increased affluence . The Framingham Heart Study, initiated in 1948, aimed to observe a large population of healthy adults over time to understand the factors contributing to heart disease. The study collected data on over 80 variables about 5,209 people before the age of computers, and the data has been used in more than 2,400 studies. The Framingham Heart Study is considered one of the top 10 cardiology advances of the twentieth century. 7.1 Early Misconceptions The text explains the misconceptions about high blood pressure in 1948 when physicians believed that high blood pressure was a natural part of aging. The Framingham Heart Study aimed to understand the factors contributing to heart disease. The text also explains the case of President Roosevelt, who died from heart disease in 1945. His personal physician hid Roosevelt's deteriorating health from his family and the public, and it's unclear whether this deception was due to medical ignorance or a deliberate cover-up. Roosevelt's death served as a wake-up call, leading to a massive research effort to understand the causes of heart disease . Today, high blood pressure is treated with medication to reduce the stress on artery walls. 7.2 The Beginning of the Study The text describes the beginning of the Framingham Heart Study in 1948. The study aimed to track a large cohort of initially healthy patients over time to understand the factors contributing to heart disease. The town of Framingham, Massachusetts was selected due to several reasons, including its population stability and willingness to participate, and its proximity to Boston, a city with several prestigious medical schools and research institutions. The study recruited 5,209 men and women between the ages of 30 and 59, which was surprising for the time as medical science believed women were immune to heart disease. Researchers later discovered that women were not immune, but acquired it at a lower rate than men . The study aimed to discover the role of family history, smoking, drinking, obesity, inadequate sleep, high blood pressure, or high cholesterol in the development of heart disease. The Data The Framingham Heart Study began in 1948 and involved collecting data on 80 different variables from 5,209 volunteers every 2 years. The collected data included personal and family history of disease, physical measurements, and samples of urine and blood. The study expanded over time to include additional risk factors such as physical activity and genomic information. The Framingham Heart Study is now in its seventh decade of collecting and analyzing data, and it has since started the Framingham Offspring Study in 1971, which follows the children of the original volunteers, and the Third Generation Study in 2002, which follows the grandchildren of the original volunteers. First Findings The first paper from the Framingham Heart Study was published in 1957 after ten years of study, reporting surprising results such as the rate of heart disease in women and high blood

pressure and high cholesterol as risk factors for heart disease. In 1961, another paper from the study showed that heart disease could be prevented by detecting and treating certain risk factors. 7.3 The Framingham Risk Score The Framingham Heart Study involved collecting data on over 80 different variables every two years from a cohort of healthy volunteers between the ages of 30 and 59, beginning in 1948. The study produced groundbreaking research, including the discovery that high blood pressure and high cholesterol are risk factors for heart disease. The statisticians working on the project developed multivariate analysis, which is now a core method used in virtually every epidemiology study. In 1998 , the Framingham Risk Score was developed, which allows physicians to predict an individual's 10-year risk of developing coronary heart disease using a simple prediction algorithm. This score is based on a multiple logistic regression model, and a points system has been developed to make the model more useful to practitioners. The data used to build the models described in this chapter can be downloaded from the online companion for the book. The Data, Variables, and Model This text describes the development and evaluation of a logistic regression model called the Framingham Risk Score, which predicts an individual's 10-year risk of developing coronary heart disease (CHD) based on age, gender, systolic blood pressure, diabetes, and smoking status. The model was developed using data from the Framingham Heart Study and was trained and tested on separate subsets of the data. The model's performance was evaluated using a Receiver Operator Characteristic (ROC) curve, which shows the trade-off between false positives and false negatives. The model achieved an area under the curve (AUC) of 0.72, indicating promising results for clinical prediction models. The text also discusses the trade-off between false positives and false negatives and presents a classification matrix showing the model's performance on the training set. Overall, the model can help physicians prioritize which patients to treat, and it can be further improved with more detailed data and advanced methods. A Points System The text describes the development of a points system for predicting the risk of developing coronary heart disease (CHD) based on risk factors such as age, blood pressure, sex, diabetes, and smoking status. The risk factors are organized into meaningful categories with assigned reference values, and a base computation is made by adding up reference values that represent low risk. A "Logit Units" column is then produced by multiplying the difference in reference value from the base value by the corresponding logistic regression coefficient for each variable. The Logit Units column is scaled and rounded to produce integer points values using a five-year increase in age as the scaling factor. The Logit equation is used to compute an estimate of the Logit for a given points value, and the probability of developing CHD can be computed using this estimate. Variable Category Reference Base Diff Logit Units

The text describes a points system that simplifies the process of calculating an individual's risk of coronary heart disease (CHD) using the Framingham Heart Study model. The risk factors are organized into categories and assigned reference values. A base computation is made by adding up the reference values that represent low risk, and the difference in reference value from the base value is multiplied by the corresponding logistic regression coefficient for that variable. The Logit Units column is then scaled and rounded to produce an integer number of points, which are used to compute the probability of developing CHD. The points system allows patients to easily see what actions they can take to reduce their risk of CHD. The text also mentions an online form that individuals can use to predict their 10-year risk of having a heart attack, but the points system adds an extra level of transparency to the model. The points system is an example of how analytics models can be simplified to become more useful to people who do not necessarily understand the mathematics behind the model. Validating the Model on Other Populations In 1999, studies were conducted to test the validity of the Framingham Risk Score in ethnically and racially diverse populations. The model performed well in whites and blacks, with only minor recalibration needed for other groups such as Japanese men, who had a much lower CHD rate. These studies provided strong evidence that the Framingham Risk Score could be used in other settings. The text also explains the use of a points system to simplify the calculation of CHD risk and how it allows patients to understand how much each action reduces their risk. 7.4 Other Impacts of the Study The Framingham Heart Study has had a significant impact beyond the Framingham Risk Score. Over 2,400 studies have used the data, and the number of publications is increasing. The study played a crucial role in the development of drugs to lower blood pressure and hypertension and paved the way for clinical decision rules in other areas of medicine. Development of Medication The development of drugs to lower blood pressure and cholesterol owes much to the Framingham Heart Study. Before the study, drugs to lower blood pressure were too toxic for practical use. But the study provided the evidence necessary to pursue clinical trials and establish the effectiveness of drugs to lower blood pressure. Similarly , the study published evidence that high cholesterol was a risk factor for heart disease, which led to the development of the first cholesterol-lowering drug in the 1970s, and subsequently, the statin drug class, which now has a $20 billion market. Clinical Decision Rules The Framingham Heart Study was influential in the development of drugs to lower blood pressure and cholesterol, and paved the way for clinical decision rules in various areas of medicine. The study's impact is evident in the increasing number of publications using its data. The Veterans Administration Trial, established as a result of the Framingham Heart Study, provided evidence that lowering blood pressure can decrease the risk of heart disease. The first statin, a cholesterol-lowering drug, was developed based on evidence published by the study in

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the early 1960s. The study's impact extends to the development of clinical decision rules, which are models that predict clinical outcomes based on patient data. Despite the many clinical decision rules that exist, they are not used as much as they could be due to their lack of user- friendliness. 7.5 A Different World The Framingham Heart Study and subsequent studies have significantly contributed to the understanding and treatment of heart disease. The study led to the development of drugs for lowering blood pressure and cholesterol, and paved the way for clinical decision rules in various medical areas. The death rate from heart disease and stroke has significantly decreased since the study, but heart disease remains the leading cause of death in the United States. The data collected by the study has influenced the treatment of heart disease globally, and the continuation of the study is expected to bring more discoveries in the future.