Contribution to authorship
JB, FA and AC conceived the study; AC, FA, JB, IDF, AAV designed the study;
KK, DC, AD and AC collected and abstracted the data; IDF, AAV undertook the statistical
analysis; AC, FA, JB, IDF, AAV, KK, AD, DC drafted the manuscript; all authors had full access to all the data, including statistical reports and tables; all authors analysed and interpreted the data; all authors critically revised the manuscript for important intellectual content; AC is the guarantor.