We will derive SRR in the derivation sample for each of the outcomes and used them to calculate ICISS for each patient. In other words, we will calculate one set of SRR for mortality within 30 days, henceforth referred to as SRR-30D, and one set of SRR for mortality within 24 hours, henceforth referred to as SRR-24H. We will then calculate two ICISS for each patient. We will use similar denotation to refer to these ICISS, i.e. ICISS-30D and ICISS-24H. Finally, we will assess the performance of ICISS-30D in predicting mortality within 30 days and within 24 hours, and repeated this analysis for ICISS-24H.