The hospital standardized mortality ratio (HSMR) is a “big-dot” summary measure that is used to track a hospital’s mortality over time. The HSMR is a tool that allows hospitals to measure and monitor their progress in quality of care.
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, diagnosis, admission category, 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. As with last year’s public release, we are including a symbol (§) to identify when the HSMR result is statistically different from the 2009–2010 baseline of 100 (p<0.05). See the Methodology section for additional information.
While the HSMR takes into consideration many of the factors associated with the risk of dying, it cannot adjust for every factor. Therefore, the HSMR is most useful to individual hospitals to track their own mortality trends. The HSMR can be used to track the overall change in mortality resulting from a broad range of factors, including changes in the quality and safety of care delivered. It is important to note that the HSMR is not designed for comparisons between hospitals.
The potential benefits of HSMR data are clearly demonstrated when individual organizations use the data and tie it to actions that make a difference in quality of care. Ever since the HSMR measure was first developed and disseminated by CIHI, many hospitals and health providers across Canada have been using it as part of their ongoing efforts to improve care.
The 2012 HSMR public release is the sixth release of HSMRs for eligible hospitals and regions across Canada. This year’s release includes HSMR results for 2007–2008 to 2011–2012. The released results are based on the new methodology introduced in February 2012 and the 2009–2010 reference year (previous reference year was 2004-2005). More details about changes to the methodology can be found in Technical Notes and Frequently Asked Questions documents available in the Methodology section of the web-site.
Because of the new reference year, the results for 2007-2010 are higher compared to the results that were provided in last year’s public release. For example, if an organization’s HSMR for 2010-2011 was 96 previously, in the 2012 public release the same organization’s HSMR result for 2010-2011 may be 106. This change is caused by the new methodology and the new reference year. Despite the changes in methodology, the HSMR trends have remained similar for the majority of organizations. For example, if an organization’s HSMR results over time were declining with the old methodology, it is likely that the result trend will still be declining with the new methodology. Therefore, we recommend the focus be on result changes over time. Five years of results using the new methodology are provided to allow for this trending.
An organization’s HSMR results are included in the public release if there are at least 2,500 HSMR discharges in each of the last three years of data being reported. If an organization meets the reporting threshold but had fewer than 2,500 discharges in earlier years, results for these years are suppressed.
In the archives you will find background material and methodological notes, as well as a link to the 2007 HSMR report, the 2009 report on sepsis and the 2010 Health Care in Canada report.
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