Agreement between self reports and proxy reports of quality of life in epilepsy patients.

Agreement between self reports and proxy reports of quality of life was examined in a sample of 292 patients with epilepsy and their designated proxies. Patients and proxies completed an 89-item Quality of Life Inventory (QOLIE-89), with the items rephrased for the proxy. Results reveal moderate correlations (product-moment r ranging from 0.29 to 0.56 for 17 multi-item scales) between self reports and proxy reports. Agreement was good for measures of function that are directly observable and relatively poor for more subjective measures. Mean scale scores were significantly different between patients and proxies for only five of 17 multi-item scales. Proxy respondents systematically reported better functioning than did patients in three scales assessing cognitive functioning (all p < 0.001). By contrast, patients reported more positive health perceptions and less seizure distress than proxies. Patient educational attainment correlated inversely with degree of disagreement between patient and proxy reports for six of the 17 QOL scales and for the overall score. In addition, proxy educational attainment correlated positively with agreement for four scales. This study indicates that for group level comparisons, proxy respondents can be substituted for adults with epilepsy having low to moderate seizure frequency. However, for individual level assessments proxies should be used with caution.