Definition: The ratio of the actual number of acute in-hospital deaths to the expected number of in-hospital deaths for conditions accounting for 80% of inpatient mortality.
A number below 100 means there were less deaths in the hospital than expected.
Method of Calculation: The HSMR is calculated as the actual number of deaths among diagnosis groups accounting for 80% of inpatient mortality divided by the expected number of deaths among diagnosis groups accounting for 80% of inpatient mortality, multiplied by 100.
In other words, the HSMR is the ratio of observed to expected deaths. Observed deaths are the actual number of deaths in the hospital.
Expected deaths are based on the sum of the probabilities of in-hospital death for cases from that hospital. Coefficients derived from a logistic regression model are used to calculate the probability of in-hospital death.
Excluding PC: Palliative care patients are not included. Palliative care patients fit specific predefined inclusion/exclusion diagnostic groups.
Source: Canadian Institute for Health Information - HSMR Technical Notes (updated September 2007).