Statistics
Statistical analyses were performed using SPSS version 22.0 statistical software package (IBM SPSS Statistics, USA). First normality tests for continuous variables were performed and as all of the continuous variables were distributed non-normally the results were given as median [inter-quartile range(IQR)]. The chi-square and Mann-Whitney U tests were used to compare nonparametric values. For the risk analysis of drop-outs variables were selected if the p value was less than 0.20 in the univariate analysis and included in multivariate analysis. Odds ratios (ORs) with relevant 95% confidence intervals (CIs) were calculated to evaluate potential associations. Values of P<.05 were accepted as significant.