External Validation of an Index to Predict Up to 9‐Year Mortality of Community‐Dwelling Adults Aged 65 and Older

Abstract

OBJECTIVES: To further validate an index predicting mortality in community‐dwelling older adults. DESIGN: A comparison of the performance of the index in predicting mortality among new respondents to the National Health Interview Survey (NHIS, 2001–2004) with that of respondents from the original development and validation cohorts (1997–2000) and a test of its performance over extended follow‐up (up to 9 years) using the original cohorts. Follow‐up mortality data were available through 2006. SETTING: NHIS. PARTICIPANTS: Twenty‐two thousand fifty‐seven new respondents to the NHIS (2001–2004) and 24,139 respondents from the original development and validation cohorts (1997–2000). MEASUREMENTS: A risk score was calculated for each respondent based on the presence or absence of 11 factors (function, illnesses, behaviors, demographics) that make up the index. Using the Kaplan‐Meier method, 5‐year mortality estimates were computed for the new and original cohort respondents and 9‐year mortality estimates for the original cohorts. RESULTS: New respondents were similar to original cohort respondents but were slightly more likely to be aged 85 and older, report diabetes mellitus, and have a body mass index of 25.0 kg/m² or greater. The model performed as well in the new cohort as it had in the original cohort. New respondents with risk scores of 0 to 1 had a 2% risk of 5‐year mortality, whereas respondents who scored 18 or higher had a 69% risk of 5‐year mortality (range 3–71% risk of 5‐year mortality in the development cohort). The index also demonstrated excellent calibration and discrimination in predicting 9‐year mortality (range 7% risk for scores of 0–1 to 92% risk for scores of ≥18, original validation cohort extended). CONCLUSION: These results further justify use of this index to estimate life expectancy in clinical decision‐making.