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

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.