“…The majority (70%) of studies originated from US institutions (n=14 [16,17,20,22,23,25,27,28,[30][31][32][33][34][35]) with the remainder from the UK (n=2 [19,21]), Belgium (n=2 [26,29]), Canada (n=1 [18]) and Sweden (n=1 [24]). The inclusion criteria allowed studies published after 1980, however almost all (90%) were published within the last 5…”