Accuracy of self-reported disability in patients with parkinsonism.

For the patient, the most important aspect of parkinsonism is the degree to which the disease interferes with daily living. The patient's self-report may be the only way in which such information can be obtained. Depression and cognitive impairment, however, may influence that self-report. In the present study, three ratings of disability, from the patient, a relative, and an independent observer, showed high levels of agreement. The patients' cognitive function made a small but significant contribution to the accuracy of their self-report judged against the relative's rating. Depression, however, played no role. Agreement between patients and relatives for individual items on the disability questionnaire was reasonably high. The results suggest that patients with parkinsonism can provide accurate self-report of their level of disability, even in the presence of depression and cognitive impairment.