Statistical analysis
Descriptive statistics included means (95% Confidence Interval) as appropriate for continuous variables and frequency for categorical variables. All analyses were performed with SPSS software version 21 and Microsoft Excel version 2013. Data elaboration, based on the comparison between two groups (IEI+ and IEI-) differing in the presence/absence of a previously diagnosed IEI, aimed to:
Assess statistical significance (p-value<0.05) of a difference between the groups, through chi-squared tests for frequency and Student t-test for mean.
Describe the correlation (p-value<0.05) between variables within a group, through Pearson correlation coefficient.