Statistical Analysis
SPSS statistics Version 22.0 (International Business Machines (IBM) Corporation) was employed for data analysis. Enumeration data were expressed as percentages and the χ2 test was used for comparisons between groups. Measurement data conforming to the normal distribution were expressed as the mean ± standard deviation (SD) and the t-test was used to make comparisons between two groups. The median [interquartile range (IQR) M(P25-P75)] was used for measurements of data not conforming to the normal distribution and the rank-sum test was used to make comparisons between two groups. Count data were expressed by rate or constituent ratio and chi-squared testing was performed. A value of P < 0.05 was considered statistically significant.