Analysis of the performance characteristics of the University of Washington Quality of Life instrument and its modification (UW-QOL-R).

Background: During a 5-year period, we analyzed 3 patient subsets from the University of Washington Quality of Life (UW-QOL) Registry and published the results. In each instance, editorial review has raised legitimate concerns regarding the UW-QOL instrument that deserve public comment. We present our response to these criticisms. Since our original publication (1993), we have added domains to the original UW-QOL instrument. These additions reflected our concern that we might be missing important elements in the spectrum of disease-specific response to treatment. Using the data we have accumulated in the last 5 years, we present an analysis of the internal consistency of the UW-QOL. We have identified those domains that are responsive (or not responsive) to treatment effect and have revised the UW-QOL accordingly to create the UW-QOL-R, which is recommended for future use.

Design: The project began January 1, 1993, after approval by the UW Human Subjects Committee. Critical comments offered by external review were collated and responded to. Internal consistency was evaluated by interitem correlation matrix (Cronbach alpha) testing.

Subjects: All new patients presenting to the UW Medical Center (Seattle) with a diagnosis of head and neck cancer were asked to participate in a prospective analysis of QOL changes during and after treatment.

Intervention: Patients completed the pretreatment QOL questionnaire on the day of their initial workup. The format for the pretreatment test was an interviewer-supervised self-administered test; the subsequent tests were self-administered and were completed at 3, 6, 12, 24, and 36 months. Other data entered for each patient included site, stage, treatment, histologic classification, reconstruction, and current status. A QOL registrar was responsible for patient follow-up, data collection, and collation. All data were entered into the departmental relational database.

Results: Criticisms by external review included the following: "it is improper to call it [UW-QOL] a measure of quality of life"; "the summary scale is problematic because it implies that each of the subscales are weighted or 'valued' equally"; "some domain questions relate to surgery specific issues. while others are specific to radiation"; "we were confused by the scoring"; and "the UW-QOL index does not specifically address the psychological impact of the disease and its treatment." After evaluation of internal consistency, the UW-QOL was modified by removing 2 domains that correlated poorly with the others. This resulted in a 10-item instrument (UW-QOL-R) with an overall internal consistency score of 0.85.

Conclusions: The UW-QOL can be effectively and accurately used to compare treatment effects in the management of head and neck cancer. With this revised instrument, the 10 items appear to measure the domains of overall QOL in a highly consistent and reliable fashion over time.