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Health-related quality of life (HRQL) studies sometimes rely, in part, on proxy information obtained from patients' significant others (spouse or close companion) or health care providers. This review: (1) provides a quantitative analysis of the results that have been reported in recent studies assessing the level of agreement between patient and proxy HRQL ratings, and (2) addresses a number of key methodological issues surrounding the use of proxy raters in HRQL research. This review concentrates on 23 studies, published between 1991-2000, that describe patient-proxy agreement for a number of well-known multidimensional HRQL instruments. In general, moderate to high levels of patient-proxy agreement were reported. Lower levels of agreement were found predominantly in studies employing a small sample size (approximately 50 patient-proxy pairs or less). In larger studies comparing patients and their significant others, median correlations were between 0.60-0.70 for physical HRQL domains and about 0.50 for psychosocial domains. Mixed results were reported in studies comparing patients and their health care providers, but most of these studies employed a relatively small sample size. Proxy raters tended to report more HRQL problems than patients themselves, but the magnitude of observed differences was modest (median standardized differences of about 0.20). Based on the current evidence, we conclude that judgements made by significant others and health care providers about several aspects of patients' HRQL are reasonably accurate. Substantial discrepancies between patient and proxy ratings occur in a minority of cases. We recommend that future studies focus on: (a) the reliability and validity of proxy ratings according to common psychometric methods, and (b) the balance between information bias due to proxy ratings and potential selection bias due to exclusion of important patient subgroups from HRQL studies.

Background and Purpose: Because many stroke survivors have cognitive and communication disorders, self-reported information on a patient's quality of life (QL) cannot always be obtained. Proxy ratings may be used to prevent exclusion of this highly relevant subgroup of patients from QL studies. The purpose of this study was to evaluate both the value and possible limitations of such proxy ratings., Methods: The patient sample was composed of 437 patients who had suffered a stroke 6 months earlier. QL was assessed by means of the Sickness Impact Profile (SIP). For 108 patients who were not communicative because of cognitive or linguistic deficits, proxy ratings on the SIP were provided by the patients' significant others. For 228 of the 329 communicative patients, both self-reported and proxy SIP ratings were obtained., Results: When mean SIP scores for patients with both self-reported and proxy-derived data available were compared, the proxy mean scores were generally in close agreement with those of the patients. However, systematic differences were noted for several SIP scales, with proxies rating patients as having more QL impairments than the patients themselves. Intraclass correlations were moderate to high for most SIP subscales (average intraclass correlation coefficient [ICC] = .63), the physical (ICC = .85) and psychosocial dimensions (ICC = .61), and the total SIP score (ICC = .77). The proxy SIP scores were sensitive to differences in patients' functional health, which supports the validity of these ratings. For all patients combined, more QL impairments were found for patients with supratentorial cortical or subcortical infarctions and hemorrhages than for patients with lacunar infarctions and infratentorial strokes. Although proxy respondents were more frequently needed for patients with the first two types of stroke, we found no evidence of biased results as a consequence of an unbalanced use of proxy respondents across the different types of stroke., Conclusions: These results suggest that the benefits of using proxy ratings for noncommunicative patients outweigh their limitations. The findings stress the need for inclusion of this important subgroup of patients in QL studies. Their significant others are able to provide useful information on these patients' QL.

Purpose: To evaluate the usefulness of caregiver ratings of cancer patients' quality of life (QL), we examined the following: (1) the comparability of responses to a brief standardized QL questionnaire provided by patients, physicians, and informal caregivers; and (2) the relative validity of these ratings., Methods: The study sample included cancer patients receiving chemotherapy, their treating physicians, and significant others involved closely in the (informal) care of the patients. During an early phase of treatment and 3 months later, patients and caregivers completed independently the COOP/WONCA charts, covering seven QL domains. At baseline, all sources of information were available for 295 of 320 participating patients (92%). Complete follow-up data were obtained for 189 patient-caregiver triads., Results: Comparison of mean scores on the COOP/WONCA charts revealed close agreement between patient and caregiver ratings. At the individual patient level, exact or global agreement was observed in the majority of cases (73% to 91%). Corrected for chance agreement, moderate intraclass correlations (ICC) were noted (0.32 to 0.72). Patient, physician, and informal caregiver COOP/WONCA scores were all responsive to changes over time in specific QL domains, but differed in their relative performance. Relative to the patients, the physicians were more efficient in detecting changes over time in physical fitness and overall health, but less so in relation to social function and pain., Conclusion: For studies among patient populations at risk of deteriorating self-report capabilities, physicians and informal caregivers can be useful as alternative or complementary sources of information on cancer patients' QL.