The World Health Organization (WHO) released the International Classification of Diseases, 11^th Revision (ICD-11) in 2018. In addition to the medical entities such as disease and injury, it contains a second component, the ICD-11 Mortality and Morbidity Statistics (MMS) linearization. The authors evaluated whether the ICD-11 MMS is appropriate for use in patient safety and quality or if a USA-specific clinical modification is necessary.