From Mondo et al. Cardiovasc J Afr. 2013 Mar; 24(2): 28–33. (http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3734881/):
Data were captured into EPI-DATA (version 3.1), cleaned and then exported to Stata version 10 for analysis. Continuous variables were summarised as mean (± standard deviation) and median (inter-quartile range), and presented in the tables. Categorical data were analysed using frequency and percentages, and results are presented in frequency tables and bar charts. Test of significance (p-value) was determined using the chi-square test. A p-value of less than 0.05 was considered significant.