Addition of the Multidimensional Prognostic Index to the Estimated Glomerular Filtration Rate Improves Prediction of Long-Term All-Cause Mortality in Older Patients with Chronic Kidney Disease

Current prognostic scores of chronic kidney disease (CKD) are not accurate in older patients. The aim of this study was to evaluate the prognostic accuracy of the Multidimensional Prognostic Index (MPI) in comparison with and in addition to the estimated glomerular filtration rate (eGFR) to predict long-term all-cause mortality in hospitalized older patients with CKD. In a prospective cohort study with a mean follow-up of 2 years, we calculated eGFR according to the Modification of Diet in Renal Disease study and collected information on functional, cognitive, nutritional, co-morbidities, drug use, and co-habitation status to calculate the MPI on 1,198 patients aged >= 65 years with a diagnosis of CKD from an hospital-based sample. The all-cause mortality incidence rate for 100 person-years was 18.3 (men 22.7 vs. women 15.3, p < 0.0001). Adding the MPI to the eGFR model significantly improved all-cause mortality prediction accuracy: The C-index increased from 0.579 to 0.648 (p < 0.0001), with correct reclassification of 25.9% of patients (Net Reclassification Improvement [NRI], 0.259, p < 0.0001; Integrated Discrimination Improvement [IDI], 3.8%, p < 0.0001). The correct reclassification was higher in patients who did not die (259/741 patients, reclassification rate = 34.9%) than in patients who died (62/457 patients, reclassification rate = 13.6%). Conversely, adding the eGFR to the MPI model seems to improve prediction accuracy less consistently. In fact, the C-index increased, but not significantly (from 0.639 to 0.648, p = 0.444), with correct reclassification of 5.8% of patients (NRI, 0.058, p = 0.012; IDI, 0.009, p = 0.001), suggesting a small, although significant improvement. Adding MPI information to the eGFR markedly improved the prediction of 2-year all-cause mortality in older patients with CKD. A multidimensional evaluation for all-cause mortality risk prediction should be considered in older patients with CKD.