The statistical analysis is conducted by the computer software SPSS 17.0.0 (SPSS Inc, Chicago, Ill). All analyses are performed according to the intention-to-treat principle. The occurrences of the primary and secondary end points are compared between the entacapone and placebo groups. The categorical data are reported as numbers with proportions, and the quantitative data are reported as medians with interquartile ranges (IQRs) or means with standard deviation. The categorical data were compared using the Chi-squared or Fisher exact test where appropriate. For the continuous data, the Mann-Whitney U-test were used for the group comparisons as appropriate. A two-sided p value of <0.05 was considered statistically significant.