Factors contributing to institutionalization in patients with Huntington's disease.

ABSTRACT

The objective of this study was to determine which factors are predictive of institutionalization in Huntington's disease. Seven hundred and ninety-nine subjects with 4313 examinations from the Baltimore Huntington's Disease Center were included in the data set; 88 of these patients with an average follow-up time of 9.2 years went from living at home to being institutionalized while being observed in our clinic. We examined demographic, genetic, and clinical variables for a relationship with institutionalization using linear regressions, a Cox proportional hazards model, and χ2 or t tests in certain cases. In our linear models, scores on the Quantified Neurologic Examination (R2=0.203, P<.001), Huntington's disease Activities of Daily Living Scale (R2=0.259, P<.001), and Motor Impairment Score (R2=0.173, P<.001) were found to have the strongest correlation with time until institutionalization. In addition, CAG repeat length (R2=0.248, P<.001) was significantly associated with disease duration at institutionalization, when controlling for age at onset. In the Cox proportional hazards model, scores on the Activities of Daily Living Scale, Mini-Mental State Examination, Quantified Neurologic Examination, and Motor Impairment Score all significantly predicted placement in long-term care. Finally, institutionalized patients were shown to have a higher CAG number and a lower level of educational attainment than patients who avoided institutionalization for at least 15 years after disease onset. Neurologic findings, functional capacity, cognitive impairment, and CAG repeat length are all likely determinants of institutionalization. In contrast with other dementing conditions like Parkinson's and Alzheimer's, psychiatric symptoms were not shown to predict institutionalization in Huntington's disease. This may illustrate the especially debilitating nature of the movement disorder of Huntington's disease in comparison with the other dementias.