The estimated glomerular filtration rate (eGFR) is a predictor of important outcomes and its reduction has been associated with the risk of all-cause mortality in both general population and elderly patients. However while reduced renal function is common in older people, the best method for estimating GFR remains unclear, especially in an acute care setting. Most studies analyzing the accuracy of eGFR in the elderly were carried out in different heterogeneous settings. In this study, we compare the prognostic value of different formulas estimating GFR in predicting the risk of in-hospital morbidity and mortality within 3 months from discharge in elderly hospitalized patients.