Validity of the Patient Generated Index as a quality-of-life measure in radiation oncology.

ABSTRACT

PURPOSE/OBJECTIVES: To evaluate psychometric properties of an instrument designed to measure individualized health-related quality of life (HRQOL). DESIGN: Repeated measures of self-reported quality of life. SETTING: An outpatient radiation therapy department in the western part of the United States. SAMPLE 86 adults with cancer receiving their first course of radiation therapy. METHODS: The Patient Generated Index (PGI), the National Comprehensive Cancer Network's Distress Thermometer (DT), and the European Organisation for Research and Treatment of Cancer Quality-of-Life Questionnaire-Core-30 (QLQ-C30). MAIN RESEARCH VARIABLES Convergent validity, responsiveness, sensitivity, and response shift. FINDINGS: PGI scores were inversely correlated with scores on the DT (r = -0.49, -0.55, -0.44; p < 0.001), as well as the role (r = 0.31, 0.4, 0.38; p < 0.01), emotional (r = 0.33, 0.41, 0.33; p < 0.01), social functioning (r = 0.27, 0.49, 0.42; p < 0.05), pain (r = -0.29, -0.39, -0.39; p < 0.01), and fatigue (r = -0.35, -0.25, -0.47; p < 0.05) QLQ-C30 subscales at all measurement times. The PGI was responsive to those reporting high or low DT scores (t = 4.42, 3.32, 2.9; p < 0.05). A small-to-moderate effect size was detected in those who had an increase (effect size = 0.51) or decrease (effect size = 0.38) in HRQOL over time. Participants reconceptualized HRQOL over time. CONCLUSIONS: Data supported the PGI as a valid measure of individualized HRQOL. IMPLICATIONS FOR NURSING The PGI potentially provides a more patient-centered measure of HRQOL in patients with cancer. Additional testing is needed in larger, more diverse groups.