A randomized trial of varenicline (Chantix) for the treatment of spinocerebellar ataxia type 3

In the article “A randomized trial of varenicline (Chantix) for the treatment of spinocerebellar ataxia type 3” by T.A. Zesiewicz et al. (Neurology® 2012;78:545–550), the description of the statistical methods used to compare the treatment and placebo groups was inaccurate. The corrected table and statistics section of the Methods is below. This change does not in any way affect the results of the study. The authors regret the error.

Statistical analysis. Baseline and demographic characteristics were summarized by standard descriptive summaries (e.g., means and SDs for continuous variables such as age and percentages for categorical variables such as gender). The characteristics of the treatment groups were compared to determine whether there were any significant differences at baseline (visit 1) in age, gender, or SARA scores; sex was compared using the Fisher exact test while all other variables were compared using the Student t test. For analysis of the 9-hole peg test and 25-foot walk test, the reciprocal of the raw values was used because the data were not normally distributed. The primary analysis was based on an intention-to-treat approach and included all subjects who were randomized into the trial. For subjects who withdrew prematurely or discontinued participation prior to visit 5, the last observation on the study drug was carried forward for the analysis. Changes in the varenicline and placebo groups were compared using the Wilcoxon Rank Sum test because the data were not normally distributed. Effect size was calculated as (difference in group means/common SD). All subjects entered into the study at visit 2 were included in the evaluation of adverse events (AEs). The frequencies of AEs by type, body system, severity, and relationship to study drug were summarized. All analyses were completed using SAS 9.2. For all analyses, α was set at 0.05. There was no correction for multiple comparisons for an initial, small study of 20 subjects.

• Copyright © 2012 by AAN Enterprises, Inc.