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.