| Author | Published Year | Country and area | Mean Age | Cases (n) | Total (n) | Prevalence (%) | Research Type |
| Vanderpump M et al. [23] | 1995 | UK | 50 ± 20 | 178 | 1051 | 16.9 | Cohort |
| Ganie M et al. [24] | 2011 | India | 30 ± 5 | 62 | 291 | 21.30 | CC |
| Mohn A et al. [25] | 2002 | Italy | 15 ± 5 | 13 | 281 | 4.62 | CC |
| Vondra K et al. [26] | 2005 | USA | 26 ± 10 | 47 | 90 | 52.22 | CS |
| Vyakaranam S et al. [27] | 2014 | India | 30 ± 10 | 30 | 60 | 50 | CS |
| Demitrost L et al. [28] | 2012 | India | 55 ± 10 | 33 | 202 | 16.3 | RS |
| Nada A [29] | 2013 | Saudi Arabia | 32 ± 10 | 27 | 42 | 64.28 | CC |
| Zhang D et al. [30] | 2014 | Changsha, China | 50 ± 20 | 244 | 1294 | 18.86 | CC |
| Hansen D et al. [31] | 1999 | Pennsylvania | 5 - 17 | 153 | 235 | 65.1 | Cohort |
| Ghazali S et al. [32] | 2010 | Nigeria | 50 ± 20 | 3 | 64 | 4.69 | CC |
| Zhang N et al. [33] | 2009 | Jiangsu, China | 60 | 50 | 416 | 12.02 | CS |
| Diez J et al. [34] | 2011 | Spain | 60 ± 20 | 34 | 318 | 10.69 | CS |
| Han C et al. [35] | 2013 | Anhui, China | 45 ± 10 | 22 | 164 | 13.41 | CS |
| Total | 896 | 4508 |