Statistical Methods

Ultimately, a patient severity index is used to compare patient outcomes across healthcare providers. If the outcome is mortality, logistic regression is used. If the outcome is cost, length of stay, or some other resource utilization, then linear regression is used. A provider is ranked based upon the differential between predicted outcome and actual outcome. The greater this differential, the higher the quality ranking. There are two ways to increase this differential. The first is to improve care to decrease actual mortality or length of stay. The second is to improve coding to increase the predicted mortality or length of stay. Ultimately, it is cheaper to increase the predicted values than it is to decrease the actual values. Many providers take this approach.