A web calculator of human mortality, based on
Foster, Karloff, and Shirley, 2016.
Note: This calculator is based on an analysis of a sample of healthy 50-70 year-olds from the NIH-AARP Diet and Health Study.
For more info see below.
This web calculator of human mortality is based on the paper How Well Do the Standard Body-Mass Index or Variations With A Different Exponent Predict Human Lifespan? by Dean Foster, Howard Karloff, and Kenneth E. Shirley, to appear in the journal Obesity . The authors fit a Cox proportional hazards model to roughly 400,000 respondents from the NIH-AARP Diet and Health Study , a survey given in 1996-1997, in which times until death were measured through the end of 2009. The main goal of the paper was to better understand the relationship between BMI (both the traditional version and a new version described in the paper) and mortality, while accounting for the effects of several other health-related and demographic variables.
The calculator above takes the inputs provided in the dropdown menus and computes the estimated distribution of time until death for the given individual based on the statistical model that was fit in the above-referenced paper (Model M3, to be specific). The top plot shows the estimated distribution of the individual's lifespan, and the bottom plot shows the individual's relative risk of death as a function of his or her BMI, where BMI is defined in the traditional way, as one's weight in kilograms divided by the square of his or her height in meters (or, equivalently, as 703*(weight in lbs.)/(height in inches)^2.). The model is not causal, however, which means that changing the value of one variable would not necessarily cause a change in one given person's expected lifespan; rather, when one changes the values of one or more input variables, one should think about the results as comparisons between different groups of people.
The baseline relative risk of 1.0 is computed not from any particular 'baseline' individual, but rather is the average risk of death across all respondents measured at their observed BMI.
The results from this data analysis are susceptible to three forms of bias:
The authors suspect that these three sources of bias explain the fact that the expected lifetimes produced by the calculator are approximately five years longer than those reported in the most recent CDC life tables (from 2011).
The authors cannot publicly share the data which were used in the analysis, but the code used to do the analysis is available on Github at https://github.com/kshirley/BMI . Please open an issue on the github repo if you have any questions or comments.