Statistical analysis
Statistical analyses were performed using commercially available computer software (SPSS v 21.0, Chicago, IL, USA). Descriptive statistical analyses were undertaken on patient characteristics and the results of IEE. Nonparametric qualitative and quantitative comparisons were performed using Pearson chi-square or Fisher’s exact test. For all analysis, a two-sided P‐value of 0.05 or less was considered statistically significant.