“…Although another model validated and refined by Kates and colleagues [12] predicted postoperative mortality rates in older patients, it unfortunately, had poor applicability for clinical practice and could not predict morbidity. In fact, postoperative morbidity rates in older patients, ranging from 15% to 67%, are higher and more noteworthy than mortality rates, which are reported to be approximately 2% to 12% [5,[12][13][14]. Thus, morbidity probably reveals more information as the dependent variable in a prediction model instead of mortality.…”