Prognostic models for predicting mortality in elderly ICU patients: a systematic review

To systematically review prognostic research literature on development and/or validation of mortality predictive models in elderly patients. We searched the Scopus database until June 2010 for articles aimed at validating prognostic models for survival or mortality in elderly intensive care unit (ICU) patients. We assessed the models' fitness for their intended purpose on the basis of barriers for use reported in the literature, using the following categories: (1) clinical credibility, (2) methodological quality (based on an existing quality assessment framework), (3) external validity, (4) model performance, and (5) clinical effectiveness. Seven studies were identified which met our inclusion criteria, one of which was an external validation study. In total, 17 models were found of which six were developed for the general adult ICU population and eleven specifically for elderly patients. Cohorts ranged from 148 to 12,993 patients and only smaller ones were obtained prospectively. The area under the receiver operating characteristic curve (AUC) was most commonly used to measure performance (range 0.71-0.88). The median number of criteria met for clinical credibility was 4.5 out of 7 (range 2.5-5.5) and 17 out of 20 for methodological quality (range 15-20). Although the models scored relatively well on methodological quality, none of them can be currently considered sufficiently credible or valid to be applicable in clinical practice for elderly patients. Future research should focus on external validation, addressing performance measures relevant for their intended use, and on clinical credibility including the incorporation of factors specific for the elderly population