![]() ![]() Why does it seem like you don't take BMI into account in determining expected life expectancy? A. BMI is included but we only report the impact of more “upstream” risk factors - diet and physical activity - which lead to the intermediate risk factors (e.g., obesity) and health outcomes. For example, physical inactivity increases cardiovascular disease risk, however, it does not predict which men will or won't develop cardiovascular disease beyond the other variables in the Project Big Life Heart Attack & Stroke calculator. Given our example, a predictive model answers the question: what is your probability of developing cardiovascular disease given you are a smoker? Sometimes risk factors that are strongly causal of a disease have low capacity to determine who will or won't develop the disease. For example, a casual model answers the question: how much of your cardiovascular disease risk is due to your smoking? The goal of a prediction model is to develop a formula for making predictions about the future occurrence of an outcome based on various exposures. What is the difference between causation and prediction? A. The goal of a causal study or model is to determine whether an exposure really causes an outcome or to estimate how big is the effect. For males, physical activity was associated with other variables that are more predictive of cardiovascular disease, so physical activity dropped out of the model. The goal of a predictive model is to get the best prediction based on a combination of variables. However, the Project Big Life Heart Attack & Stroke calculator is a predictive model-it predicts the chance of future occurrence of cardiovascular disease. I am a male, why doesn't my physical activity change my cardiovascular disease risk? A. Physical activity is an important contributor to cardiovascular disease risk (i.e., there is a causal relationship). If your activity isn’t listed, assess the level of intensity based on the above descriptions and add your hours to the appropriate group. Light activities cause your heart to beat slightly faster than normal (i.e., you can still talk and sing). Moderate-intensity activities require a moderate amount of effort and your heart beats faster than normal – (i.e., you can talk but not sing). Vigorous-intensity activities are those that require a large amount of effort and cause rapid breathing and a substantial increase in heart rate (i.e., you can’t talk or your talking is broken up by large breaths). None of the physical activities I participate in are listed in your calculator so how can I assess my physical activity? A. We have divided the physical activity questions into three intensity groups and provided examples that reflect the typical energy cost of the activities. We hope to update the calculator in the future to include more details about diet. ![]() However, like many other studies, we found that there is a strong link between fruit and vegetable consumption and health outcomes. Our biggest constraint is the underlying data that we use to generate our risk algorithms that only had six brief diet questions. Why don’t the diet questions take into account fat, sugar, meat, dairy, etc.? A. Our calculator uses fruit and vegetables as a broad measure of diet quality. Our study, like many others, found anĪssociation between greater consumption of potatoes or fruit juice and Potatoes are unhealthy, but that high potato consumption is seen in people Why are potatoes and fruit juice “bad” and vegetables are “good”? A. It is not necessarily that ![]()
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