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Canadian Institute for Health Information 2008 Hospital Standardized Mortality Ratio (HSMR) Public Release

Introduction to the HSMR

The HSMR is a “big dot” summary measure that is used to track a hospital’s mortality over time. It provides an important starting point for hospitals and health regions to assess their mortality rates and identify areas for improvement.

Definition and Interpretation of the HSMR

The HSMR is the ratio of actual (observed) deaths to expected deaths. It focuses on the diagnosis groups that account for the majority of in-hospital deaths. Using a logistic regression model, it is adjusted for several factors that affect in-hospital mortality, including age, sex, length of stay, admission category, diagnosis group, comorbidity and transfer from another acute care institution. An HSMR equal to 100 suggests that there is no difference between a local mortality rate and the average national experience, given the types of patients cared for. An HSMR greater or less than 100 suggests that a local mortality rate is higher or lower than the national experience, respectively. This year, we are including a symbol (§) to identify if the HSMR result being reported is statistically different from the 2004–2005 baseline of 100 (p<0.05). See methodology section for additional information.

The 2008 HSMR Public Release

This year CIHI is reporting one measure. The HSMR (previously referred to as HSMR All Cases) being reported does not include patients whose most responsible diagnosis was palliative care (patients whose hospitalization was for the purpose of palliative care or patients who received palliative care for the largest portion of their hospital stay). It does include some patients who were admitted as acute care cases and received some palliative care (not representing the largest portion of their length of stay). This HSMR is a more stable measure for monitoring mortality trends and informing quality improvement efforts in hospitals.

Last year, CIHI also reported a second measure, the HSMR Excluding Palliative Care, which excluded all palliative care cases from the calculation. This result does not reflect mortality trends for a growing number of organizations, as there have been changes over time in the identification of patients receiving palliative care. While there has been considerable effort by hospitals to implement palliative care coding in line with the updated CIHI palliative care coding guideline and subsequent standard, these changes result in the HSMR Excluding Palliative Care trend being broken.

This release includes HSMR results for those large regions, hospital corporations and facilities across Canada, excluding Quebec, with at least 2,500 HSMR separations in each of the fiscal years 2004–2005, 2005–2006, 2006–2007 and 2007–2008.

Benefits and Limitations

Many Canadian hospitals are actively engaged in efforts to improve care. The HSMR is one more tool that allows hospitals to measure and monitor their progress.

While the HSMR calculation adjusts for many of the factors that influence the risk of dying in hospital, each hospital and community is unique; direct comparisons between hospitals are not recommended. 

No single measure can reflect all aspects of quality of care. Other indicators may also offer different perspectives on performance. Users of the HSMR are encouraged to consider a suite of performance measures, not just the HSMR, when assessing and monitoring the quality of care they are providing. Furthermore, while indicators can be a good source of information, there may be contextual, system and other factors that cannot be accounted for in the calculations, and additional data sources and investigation may be required for interpretation.

Implementation of broad, system-wide initiatives may take time. Several years may be needed to see changing trends in HSMR results.

Academic Discussion and Debate

Following CIHI’s November 2007 public release of hospital- and region-specific HSMRs, articles were published regarding the validity and utility of HSMRs to monitor the quality and safety of health care delivery within Canadian hospitals.

HSMR, like all indicators, has its limitations, and CIHI examined the concerns highlighted in the above-mentioned literature. Despite these concerns, we believe the HSMR can still be used for its intended purpose: to act as a composite screening measure for hospitals to track their changes in mortality. CIHI is committed to providing accurate and useful measures and we will continue to work with stakeholders to refine the HSMR.

Archive

2007 HSMR Report

Contact us: hsmr@cihi.ca

Page last updated December 10, 2008