Statistical analyses
Statistical data analysis was performed using SPSS.21 version. Normality analysis showed that all continuous variables for all groups did not confirm normal distribution. Categorical variables were summarized as frequencies and percentages; continuous variables were given by using means and standard deviations when normally distributed, median (min-max) when abnormally distributed. Two measures of reliability were included: internal consistency and test–retest reliability. Internal consistency was tested using Cronbach’s alpha for the patient group. Test–retest reliability was carried out using Intraclass Correlation (ICC). Construct validity was assessed by estimating Spearman’s correlation coefficients between the subscales of the CVID QoL TR and the items of the SF-36. Additionally, Mann- Whitney U test and Kruskal- Wallis test was conducted to evaluate the discriminant validity of the tool.