Initial comparison of descriptive statistics for all clinical variables was performed using either analysis of variance or chi-squared tests, depending on whether the variables were quantitative or categorical. To allow comparison among studies, the ARCS scores were then standardized (to Z scores) using the mean and SD of the normal population reported by Schofield et al. 21 Bivariate linear correlation analysis of standardized ARCS scores was performed using Pearson's (r) coefficient tests.