COMPARISON OF PATIENT AND PROXY EORTC QLQ-C30 RATINGS IN ASSESSING THE QUALITY-OF-LIFE OF CANCER-PATIENTS

The aim of this study was to examine whether significant others can pr ovide useful proxy information on the health-related quality of life ( QL) of cancer patients. We examined the level and pattern of agreement between patient and proxy ratings of the EORTC QLQ-C30, the reliabili ty and validity of both types of information, and the influence of sev eral factors on the extent of agreement. at ratings were obtained for 307 and 224 patient-proxy pairs (at baseline and follow-up, respective ly). Agreement was moderate to good (ICC = 0.42 to 0.79). Multitrait-m ultimethod analysis showed good convergence and discrimination of spec ific at domains. Comparison of mean scores revealed a small but system atic bias between patient and proxy ratings. The maximum level of disa greement was found at intermediate levels of at, with smaller discrepa ncies noted for patients with either a relatively poor or good at. Bot h patient and proxy QL ratings were reliable and responsive to changes over time. Several characteristics of the patients and their signific ant others were found to be associated with the level of agreement, bu t explained less than 15% of the variance in patient-proxy differences . In conclusion, the present findings lend support to the viability of employing significant others as proxy respondents of cancer patients' quality of life where this is necessary. (C) 1998 Elsevier Science In c.