Statistical Analysis
Statistical analysis was performed using the Statistical Package for the Social Sciences (SPSS) version 21.0 software statistical package program (SPSS Inc., Chicago, IL). The variables were investigated to determine whether or not they are normally distributed. Descriptive analyses were presented using means and standard deviations for normally distributed values and frequencies were presented as percentages. Mean and median values of two-independent groups compared with independent samples t-test or Mann Whitney U test where appropriate. Multiple groups were compared with Kruskal Wallis test and The Jonckheere-Terpstra test was used to determine if there was a statistically significant trend across groups. The Chi-square or Fisher’s exact test, where appropriate, was used to compare proportions in different groups. A p-value of less than 0.05 was considered to show a statistically significant result.