“…1. Four studies were conducted on populations in Australia, 12,28,44,51 three in Saudi Arabia, 50,52,53 two in China, 54,55 one with populations in China and India, 30 two in Hong Kong Special Administrative Region, 17,56 three in the United Kingdom, 35,49,57 two in USA, 11,43 two in Japan, 47,58 and one from each of the following countries: Canada, 59 Korea, 32 Ukraine, 60 Ireland, 48 Turkey, 61 Spain, 62 Sweden, 18 Slovenia, 37 Denmark, 74 and Singapore. 39 There were no studies appraised to be of high risk of bias.…”