A comparison of two patient classification instruments in an acute care hospital

Patient classification systems are alternately praised and vilified by staff nurses, nurse managers, and nurse executives. Most nurses agree that substantial resources are used to create or find, implement, manage, and maintain the systems, and that the predictive ability of the instruments is intermittent. The purpose of this study is to compare the predictive validity of two types of patient classification instruments commonly used in acute care hospitals in California.

Acute care hospitals in California are required by both the Joint Commission on Accreditation of Healthcare Organizations and California Title 22 to have a reliable and valid patient classification system (PCS). The two general types of systems commonly used are the summative task type PCS and the critical incident or criterion type PCS. There is little to assist nurse executives in deciding which type of PCS to choose. There is modest research demonstrating the validity and reliability of different PCSs but no published data comparing the predictive validity of the different types of systems. The unit of analysis is one patient shift called the study shift. The study shift is defined as the first day shift after the patient has been in the hospital for a full 24 hours. Data were collected using medical record review only. Both types, criterion and summative, of PCS data collection instruments were completed for all patients at both collection points. Each patient had a before and after score for each type of instrument. Three hundred forty-nine medical records for inpatients meeting the inclusion criteria were examined.

The average patient age was 76 years, the average length of stay was 6.6 days with an average of 6.7 secondary diagnoses recorded. Fifty-five percent of the sample was female and the most common primary diagnosis was CHF, followed by COPD, CVA, and pneumonia. There was a difference in mean summative predictor score and the mean summative actual score of 1.57 points with the predictor score higher (P =.001; CI =.62--2.5). For the criterion instrument, 68.4% of the predictor criterion scores were in category 2 compared to 65.5% of the actual criterion scores. The criterion predictor agreed with the criterion actual score 45% of the time for category 1 patients, 87.3% of the time for category 2 patients, 77.1% of the time for category 3 patients and 72.7% of the time for category 4 patients, with an overall agreement between predictor and actual criterion scores of 79.9% (Kappa P <.001, indicating agreement is not by chance).

The most significant finding of this study is that there are virtually no differences in the predictive ability of summative versus criterion patient classification instruments. Using the same patients, both types of instruments predicted the actual score over 78% of the time.