About Calculations

To create the calculators, we used information from older adults collected in two large nationally representative surveys: The National Health Interview Survey and the Health and Retirement Survey.  As part of these surveys, in the late 1990’s, U.S. adults were asked about their health behaviors (e.g., smoking), disease burden (e.g., history of diabetes) and function (e.g., difficulty walking several blocks).  We followed respondents to determine if and when they died.  We used statistical methods to learn which factors were most highly associated with chance of death.

We assigned a point value to the factors most most associated with death.  Factors that were more highly associated with death received a higher point value (e.g., being a current smoker is assigned more points than never having smoked).  We calculated a total point score for each respondent based on the presence or absence of factors associated with death.  We then looked at the chance of death for adults with each point score over 4 to 10 years.  We also calculated total point scores for adults that responded to each of the surveys but whose information was not used to identify factors associated with death.  We wanted to make sure that the point scores were associated with similar chances of death in these adults and they were.

Since we used two different surveys to develop the calculators we initially had two separate calculators.  We combined the information from the two calculators into one calculator (15 questions) for this application to give more robust estimates of chance of death in 10 years.