“…Methodological characteristics of the studies Table 1 shows the methodological characteristics of the 10 studies 20,21,22,23,24,25,26,27,28,29 analyzed in the current review. Half of the studies were conducted in developed countries, the oldest 20 failed to specify the country but used U.S. data in its analysis, three studies were performed in the United States 21,22,23 , and one in Israel 24 .…”