Survival Prediction for Terminally Ill Cancer Patients: Revision of the Palliative Prognostic Score with Incorporation of Delirium

Abstract

An existing and validated palliative prognostic (PaP) score predicts survival in terminally ill cancer patients based on dyspnea, anorexia, Karnofsky performance status score, clinical prediction of survival, total WBC, and lymphocyte percentage. The PaP score assigns patients to three different risk groups according to a 30-day survival probability--group A, >70%; group B, 30%-70%; group C, <30%. The impact of delirium is known but was not incorporated into the PaP score. Our aim was to incorporate information on delirium into the PaP score based on a retrospective series of 361 terminally ill cancer patients. We followed the approach of "validation by calibration," proposed by van Houwelingen and later adapted by Miceli for achieving score revision with inclusion of a new variable. The discriminating performance of the scores was estimated using the K statistic. The prognostic contribution of delirium was confirmed as statistically significant (p < .001) and the variable was accordingly incorporated into the PaP score (D-PaP score). Following this revision, 30-day survival estimates in groups A, B, and C were 83%, 50%, and 9% for the D-PaP score and 87%, 51%, and 16% for the PaP score, respectively. The overall performance of the D-PaP score was better than that of the PaP score. The revision of the PaP score was carried out by modifying the cutoff values used for prognostic grouping without, however, affecting the partial scores of the original tool. The performance of the D-PaP score was better than that of the PaP score and its key feature of simplicity was maintained.