Understanding the Outcomes Measures used in Huntington Disease Pharmacological Trials: A Systematic Review

Background: The identification of the gene mutation causing Huntington disease has raised hopes for new treatments to ease symptoms and slow functional decline. As such, there has been a push towards designing efficient pharmacological trials (i. e., drug trials), especially with regard to selecting outcomes measures that are both brief and sensitive to changes across the course of the disease, from subtle prodromal changes, to more severe end-stage changes. Objectives: Recently, to aid in efficient development of newHDresearch studies, the National Institute of Neurological Disorders and Stroke (NINDS) published recommendations for measurement selection in HD. While these recommendations are helpful, many of the recommended measures have little published data in HD. As such, we conducted a systematic review of the literature to identify the most common outcomes measures used in HD clinical trials. Methods: Major medical databases, including PubMed, Embase, CINAHL, and the Cochrane Central Register of Controlled Trials, were used to identify peer-reviewed journal articles in English from 2001 through April 2013; 151 pharmacological trials were identified. Results: The majority of HD clinical trials employed clinician-reported outcomes measures (93%); patient reported outcome measures (11%) and observer reported outcome measures (3%) were used with much less frequency. Conclusions: We provide a review of the most commonly used measures across these trials, compare these measures to the clinical recommendations made by the NINDS working groups, and provide recommendations for selecting measures for future clinical trials that meet the Food and Drug Administration standards.