Statistical analysis Statistical analysis was performed using SPSS 22.0 software (IBM, Armonk, NY, USA). Measurement data were expressed as mean ± SD. Normality test and variance homogeneity test were conducted. Normally distributed data with homogeneity were compared using one-way analysis of variance. Non-normally distributed data were compared using Wilcoxon two-sample rank sum test. Ranked data were analyzed using rank sum test. A value of P < 0.05 was considered statistically significant. Results followed the intention-to-treat principle.