Frailty Before Critical Illness and Mortality for Elderly Medicare Beneficiaries

Objectives: To estimate the effect of pre-intensive care unit (ICU) health categories on mortality during and after critical illness, focusing specifically on the effect of pre-ICU frailty on short- and long-term mortality.

Design: Retrospective cohort study.

Setting: Medicare claims data from 2004 to 2008.

Participants: A nationally representative sample of elderly Medicare beneficiaries admitted to an ICU in 2005.

Measurements: Participants were classified into four pre-ICU health categories (robust, cancer, chronic organ failure, frailty) using claims data from the year before admission, allowing for assignment to multiple categories. The association between pre-ICU health category and hospital and 3-year mortality was assessed using multivariable logistic regression and Cox proportional hazards models.

Results: Of 47,427 elderly individuals in the ICU, 18.8% were robust, 28.6% had cancer, 68.1% had chronic organ failure, and 34.0% were frail; 41.3% qualified for multiple categories. Overall hospital mortality was 12.6%, with the lowest mortality for robust participants (9.7%). Participants with pre-ICU frailty had higher hospital mortality than those with the same pre-ICU health categories without frailty. (Adjusted odds ratios ranged from 1.27 (95% confidence interval (CI) 1.10-1.47) to 1.52 (95% CI = 1.35-1.63).) Robust hospital survivors had the lowest 3-year mortality (24.6%). Pre-ICU frailty conferred higher 3-year mortality than pre-ICU categories without frailty. (Adjusted hazard ratios ranged from 1.54 (95% CI = 1.45-1.64) to 1.84 (95% CI = 1.70-1.99).)

Conclusion: Critically ill elderly adults can be categorized according to pre-ICU health categories. These categories, particularly pre-ICU frailty, may be important for understanding risk of death during and after critical illness.