Seventy-five consecutive patients were selected to evaluate a disease-specific quality-of-life questionnaire (UW QOL). The new test was compared to two established equality of life evaluation tools, the Karnofsky scale and the Sickness Impact Profile (SIP). Each test was administered on three separate occasions: (1) several days preoperatively; (2) immediately postoperatively; and (3) 3 months postoperatively.
The Karnofsky scale is relatively crude and lacks the ability to measure subtle changes. The SIP is a detailed questionnaire that is quite sensitive to change. However, due to its length, the SIP is inefficient and expensive to administer, and patient noncompliance is often a problem.
The three questionnaires were compared according to the following factors: Acceptability: 97% of the patients favored the UW QOL scale compared with the SIP because it was more concise and easier to complete. Validity: Validity indicates the ability of the test under investigation to measure what it was intended to measure. Using the SIP as a gold standard, the UW QOL scale demonstrated an average criterion validity of 0.849, whereas the Karnofsky average criterion validity was 0.826. Reliability: Reliability is a measurement of the reproducibility of the data. The UW QOL questionnaire scored >0.90 on reliability coefficients versus 0.80 for the Karnofsky and 0.87 for the SIP scale. Responsiveness: Responsiveness is the ability of the test to measure clinical change. The UW QOL scale faired better than the Karnofsky and the SIP scale in detecting change.
The UW QOL scale is comparable to the Karnofsky and SIP scales when tested for validity and reliability. It was the preferred test format of 97% of patients and provided the greatest responsiveness to clinical change.