“…There were 14 RCTs (n = 3,971) performing only around the time of ET. The quality of the included trials is summarized in table 1; 7 of the 14 studies were published as full reports [17,18,19,20,21,22,23], while the remaining 7 were published as conference abstracts [10,11,24,25,26,27,28]; 4 of the studies were in Europe (2 in Denmark [17,18], 1 in Brazil [11], 1 in Germany [20]), 3 in China [21,22,23] and 7 in the USA [10,18,19,24,25,26,27]. …”