Normality was assessed by means of the Kolmogorov-Smirnov test. Differences between the groups were analyzed by using an unpaired two-tailed t test for continuous variables and the X2 test for binomial outcomes (Stata 10 Edition for Windows, StataCorp LP, College Station, TX). The pain scores over time and their interaction with the intervention were analyzed by means of the analysis of variance for repeated measures (SPSS 15.0.0, SPSS Inc., Chicago, IL). Effects were considered statistically significant for P<.05