Data on covariates were extracted from patient records or from the patients or their accompanying relatives. Injuries were also extracted from patient records, including imaging reports and operation notes and were then coded using ICD-10. We will calculate the SRR for to each unique ICD-10 code using SRR=A/(A+B), where A denotes the number of surviving patients with a specific ICD-code and B is the number of non-surviving patients with the same specific ICD-code. The calculated SRR gets a value between zero and one. One represents 100% survival and zero represents 0% survival. We will calculate the final ICISS score for each patient as the product of all individual SRRs. Hence, ICISS also ranges from 0 to 1 and should be interpreted as the patient's probability of survival. This method is commonly referred to as the conventional ICISS.