| Country/area
| Study (year) | Patients () | Population/ participants | Prevalence (per 100,000) |
| Northern Europe | | | | | UK (Yorkshire) | Chamberlain (1977) [5] | 32 | 5,000,000 | 0.64 | Scotland | Jankowski et al. (1992) [6] | 15 | 5,500,000 | 0.3 | Ireland (Dublin) | Kilmartin et al. (1997) [7] | 24 | 1,058,264 | 2.27 | Sweden (Skane) | Mohammad et al. (2013) [8] | 40 | 809,317 | 4.94 | Europe | | | | | Germany | Papoutsis et al. (2006) [9] | 165 | 3,391,344 | 4.87 | France (Paris) | Mahr et al. (2008) [10] | 79 | 1,094,412 | 7.1 | Italy (Rome) | Valesini et al. (1991) [11] | 155 | NA | 19 | Greece | Kaklamani et al. (2000) [12] | 90 | NA | 11 | Mediterranean | | | | | Turkey | | | | | Tokat | Baş et al. (2016) [13] | 14 | 2,325 | 602 | Kayseri | Çölgeçen et al. (2015) [14] | 9 | 5,218 | 170 | Havsa | Cakir et al. (2004) [15] | 1 | 4,861 | 20 | Istanbul | Azizlerli et al. (2003) [16] | 101 | 23,986 | 420 | Ankara | Idil et al. (2002) [17] | 16 | 17,256 | 110 | Ordu | Yurdakul et al. (1988) [18] | 19 | 5,121 | 370 | Istanbul | Demirhindi et al. (1981) [19] | 4 | 4,940 | 80 | Mediterranean | | | | | Iran | Davatchi et al. (2007) [20] | 7 | 10,291 | 68 | Egypt | Assaad-Khalil et al. (1997) [21] | 274 | NA | 16 | Jordan | Madanat et al. (2000) [22] | 200 | NA | 27 | Others | | | | | US (Olmsted County) | Calamia et al. (2009) [23] | 13 | 144,248 | 5.2 | Japan | Nakae et al. (1993) [24] | 3316 | NA | 13.5 | Korea | Bang et al. (2011) [25] | 15,554 | NA | 30.2 | China | Zhang et al. (2006) [26] | 1996 | NA | 14 |
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