Standardized mortality ratios (SMRs), used for decades in numerous countries, including the United States, are not an accurate reflection of preventable hospital deaths, according to a new study published in the British Medical Journal.
Under the SMR measure, hospitals compare their numbers of deaths to expected numbers based on administrative data. Researchers, led by Helen Hogan, M.D., and Nick Black of the London School of Hygiene & Tropical Medicine, analyzed 3,400 deaths in 34 randomly selected hospital trusts in the United Kingdom. They reviewed the data along with patients' case notes and compared the numbers to the SMR and Summary Hospital Level Mortality Indicator. They found 3.6 percent of hospital deaths were avoidable, with no significant associations between that percentage and hospital-wide SMRs.
"Hospital-wide SMRs can be distracting and potentially misleading and should not be used as a basis to praise or condemn a hospital or trust. We need to support and help hospitals to raise standards not criticize and punish them," Black said in a statement. "Given the complexity of hospitals, with many different clinical departments and activities, it is more helpful for the public, patients, staff and politicians to use a variety of specific measures of quality, such as adherence to good practice guidelines; outcomes for specific diseases or procedures; patient surveys of their experiences; infection rates; and staff surveys."
The researchers suggested hospitals use SMRs only to assess care quality for high-mortality conditions with readily available, high-quality clinical data. Their findings echo 2012 research on the reliability of mortality rates as a quality measure, as well as more general complaints that common quality measures penalize hospitals for factors beyond their control.