Mortality index

The mortality index, or the ratio of observed to expected mortality, is a reported quality metric that has been assumed to directly reflect patient care. However, documentation and coding that does not use knowledge of how a reported mortality index is derived could reflect poorly on a hospital or service line.

The standardised mortality index (SMI) is calculated, for a given group, as the ratio of the number of deaths actually observed over a given period and the number of deaths that would have occurred over the same period if the group had been subject to the same age-specific mortality as the population as a whole. A ratio of more than 1 is interpreted as excess mortality in the group.

It is a measure calculated from the observed or actual mortality and expected or predicted mortality based on documentation and risk assessment, is particularly utilized in neurosurgical services as a metric of quality of care. Diagnosis and treatment provided at admission is defined by a diagnosis-related group (DRG) code that is generated at discharge and CMS determines reimbursement based on DRG codes, which are adjusted according to both ROM and SOI