Agreement between clinician-rated versus patient-reported outcomes in Huntington disease

Background: Clinician-rated measures of functioning are often used as primary endpoints in clinical trials and other behavioral research in Huntington disease. As study costs for clinician-rated assessments are not always feasible, there is a question of whether patient self-report of commonly used clinician-rated measures may serve as acceptable alternatives in low risk behavioral trials. Aim: The purpose of this paper was to determine the level of agreement between self-report and clinician-ratings of commonly used functional assessment measures in Huntington disease. Design: 486 participants with premanifest or manifest Huntington disease were examined. Total Functional Capacity, Functional Assessment, and Independence Scale assessments from the Unified Huntington Disease Rating scale were completed by clinicians; a self-report version was also completed by individuals with Huntington disease. Cronbach’s α was used to examine internal consistency, one-way analysis of variance was used to examine group differences, and paired t tests, kappa agreement coefficients, and intra-class correlations were calculated to determine agreement between raters. Results: Internal consistency for self-reported ratings of functional capacity and ability were good. There were significant differences between those with premanifest, early-, and late-stage disease; those with later-stage disease reported less ability and independence than the other clinical groups. Although self-report ratings were not a perfect match with associated clinician-rated measures, differences were small. Cutoffs for achieving specified levels of agreement are provided. Conclusions: Depending on the acceptable margin of error in a study, self-reported administration of these functional assessments may be appropriate when clinician-related assessments are not feasible.