The most appropriate primary outcomes to design clinical trials on Huntington's disease: meta-analyses of cohort studies and randomized placebo-controlled trials

Measuring the functional impact of cognitive impairment in Huntington’s disease

Background

Patients with Huntington’s disease (HD) exhibit a variable predominance of cognitive, behavioral and motor symptoms. A specific instrument focusing on the impact of cognitive impairment in HD over functional capacity is lacking.

Objective

To address the need for a brief and specifically developed HD questionnaire able to capture functional aspects suspected to be sensitive to cognitive impairment.

Methods

We developed and validated the “Huntington’s Disease-Cognitive Functional Rating Scale” (HD-CFRS) in 78 symptomatic carriers of the Huntington’s disease mutation. We also administered the HD-CFRS to a knowledgeable informant to measure the level of agreement. To explore the association between HD-CFRS scores and participants’ cognitive status, we administered objective measures of cognition. Participants were classified as cognitively preserved (HD-NC), as having mild cognitive impairment (HD-MCI), or as having dementia (HD-Dem).

Results

The HD-CFRS showed concurrent validity and internal consistency in the three groups. HD carriers and informants in the HD-NC group obtained similar HD-CFRS scores. However, in patients with mild cognitive impairment and dementia, informers reported greater functional impairment than HD participants. The HD-CFRS total score showed strong correlations with measures assessing cognition.

Conclusions

These findings support the utility of the HD-CFRS as a brief and reliable instrument to measure functional defects associated with cognitive impairment in HD. We believe this questionnaire could be a useful tool both for clinical practice and research.

Motor, cognitive, and functional declines contribute to a single progressive factor in early HD

OBJECTIVE

To identify an improved measure of clinical progression in early Huntington disease (HD) using data from prospective observational cohort studies and placebo group data from randomized double-blind clinical trials.

METHODS

We studied Unified Huntington Disease Rating Scale (UHDRS) and non-UHDRS clinical measures and brain measures of progressive atrophy in 1,668 individuals with early HD followed up prospectively for up to 30 to 36 months of longitudinal clinical follow-up.

RESULTS

The results demonstrated that a composite measure of motor, cognitive, and global functional decline best characterized clinical progression and was most strongly associated with brain measures of progressive corticostriatal atrophy.

CONCLUSIONS

Use of a composite motor, cognitive, and global functional clinical outcome measure in HD provides an improved measure of clinical progression more related to measures of progressive brain atrophy and provides an opportunity for enhanced clinical trial efficiency relative to currently used individual motor, cognitive, and functional outcome measures.