Predicting Patient Mortality Rates for Providers
e statistical methods used to predict mortality on the basis of the significant risk factors are tested to determine
whether they are sufficiently accurate in predicting mortality for patients who are extremely ill prior to undergoing the procedure as well as for patients who are relatively healthy. ese tests have confirmed that the models are reasonably accurate in predicting how patients of all different risk levels will fare when undergoing PCI.
e mortality rate for each hospital and cardiologist is also predicted using the statistical model. is is accomplished
by adding the predicted probabilities of death for each of the provider’s patients and dividing by the number of patients.
e resulting rate is an estimate of what the provider’s mortality rate would have been if the hospital’s performance was
identical to the state performance. e percentage is called the predicted or expected mortality rate (EMR). A hospital's EMR is contrasted with its observed mortality rate (OMR), which is the number of PCI patients who died divided by the total number of PCI patients.
Computing the Risk-Adjusted Mortality Rate
e risk-adjusted mortality rate (RAMR) represents the best estimate, based on the associated statistical model, of what
the provider’s mortality rate would have been if the provider had a mix of patients identical to the statewide mix. us, the RAMR has, to the extent possible, ironed out differences among providers in patient severity of illness, since it arrives at a mortality rate for each provider based on an identical group of patients.
To get the RAMR, the OMR is first divided by the provider’s EMR. If the resulting ratio is larger than one, the provider has a higher mortality rate than expected on the basis of its patient mix; if it is smaller than one, the provider has a lower mortality rate than expected from its patient mix. e ratio is then multiplied by the overall statewide rate (0.95 percent in-hospital/30-day in 2008) to obtain the provider’s RAMR.
Interpreting the Risk-Adjusted Mortality Rate
If the RAMR is lower than the statewide mortality rate, the hospital has a better performance than the state as a whole; if the RAMR is higher than the statewide mortality rate, the hospital has a worse performance than the state as a whole.
e RAMR is used in this report as a measure of quality of care provided by hospitals and cardiologists. However,
there are reasons that a provider’s RAMR may not be indicative of its true quality.
For example, extreme outcome rates
may occur due to chance alone. is is particularly true for low-volume providers, for whom very high or very low rates are more likely to occur than for high-volume providers. To prevent misinterpretation of differences caused by chance variation, expected ranges (confidence intervals) are included in the reported results.
Differences in hospital coding of risk factors could be an additional reason that a hospital’s RAMR may not be reflective of quality of care. e Department of Health monitors the quality of coded data by reviewing patients’ medical records to ascertain the presence of key risk factors. When significant coding problems are discovered, hospitals are required to correct these data and are subject to subsequent monitoring.
How This Initiative Contributes to Quality Improvement
e goal of the Department of Health and the Cardiac Advisory Committee is to improve the quality of care in relation
to cardiac surgery and angioplasty in NYS. Providing the hospitals, cardiac surgeons (who perform cardiac surgery) and cardiologists (who perform PCI) in NYS with data about their own outcomes for these procedures allows them to examine the quality of their own care and to identify opportunities to improve that care.
e data collected and analyzed in this program are reviewed by the Cardiac Advisory Committee, which assists with
interpretation and advises the Department of Health regarding which hospitals and physicians may need special attention. Committee members have also conducted site visits to particular hospitals and have recommended that some hospitals obtain the expertise of outside consultants to design improvements for their programs.