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Assessing quality of life after stroke. The value and limitations of proxy ratings
K C Sneeuw1, N K Aaronson, R J de Haan
1Division of Psychosocial Research and Epidemiology, The Netherlands Cancer Institute, Antoni van Leeuwenhoek Hospital, Amsterdam, The Netherlands.
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.