Table 1. The characteristics of the included studies.
| Study | Type (n) | Validation process & Tool | Prevalence | OSA definition | No OSA AHI <5 (n) | Mild OSA AHI ≥5 (n) | Moderate-to-severe OSA AHI ≥15 or RDI >15 (n) | Severe OSA AHI ≥30 or RDI ≥30 (n) |
|---|---|---|---|---|---|---|---|---|
| Sleep clinic population | ||||||||
| [ 20 ]Ong 2010 | Asian population (319) | Prospective Lab PSG | 77.7 | AHI >5 | 79 | 240 | 166 | 113 |
| [ 21 ]Farney2011 | American population (1426) | Retrospective Lab PSG | 89.5 | AHI ≥5 | 150 | 1274 | 959 | 580 |
| [ 22 ]El-Sayed2012 | Egyptian population (234) | Prospective Lab PSG | 87.2 | AHI ≥5 | 30 | 204 | 177 | 148 |
| [ 23 ]Yu2012 | Chinese population (114) | Prospective Lab PSG | 79.8 | AHI ≥5 | 23 | 91 | 67 | 46 |
| [ 24 ]Boynton2013 | American population (219) | Prospective Lab PSG | 77.1 | AHI >5 | 50 | 169 | 103 | 62 |
| [ 25 ]Pereire2013 | Canadian population (128) | Prospective Lab PSG | 91.3 | AHI >5 | 12 | 116 | 88 | 56 |
| [ 26 ]Vana2013 | American population (47) | Prospective Lab PSG | 68.0 | AHI >5 | 15 | 32 | 19 | 9 |
| [ 27 ]Cowan2014 | British population (129) | Prospective Portable level 3 PSG | 75.2 | AHI ≥5 | 32 | 97 | 56 | NA |
| [ 28 ]Ha2014 | Chinese population (139) | Prospective Lab PSG | 79.8 | AHI >5 | 28 | 111 | 84 | 51 |
| [ 29 ]Luo2014 | Chinese population (194) | Prospective Lab PSG | 92.4 | AHI ≥5 | 8 | 186 | 170 | 128 |
| [ 30 ]Reis2015 | Portuguese population (216) | Prospective Lab/portable level 3 PSG | 78.1 | AHI >5 | 47 | 168 | 113 | 61 |
| Surgical population | ||||||||
| [ 17 ]Chung2008 | Canadian population (177) | Prospective Lab PSG | 68.9 | AHI >5 | 55 | 122 | 70 | 39 |
| [ 18 ]Chung2012 | Canadian population (746) | Prospective Lab/portable level 2 PSG | 68.4 | AHI >5 | 236 | 510 | 287 | 134 |
| [ 19 ]Nunes2014 | Brazilian population (81) | Prospective Lab PSG | 48.1 | AHI ≥15 | AHI <15 = 43 | 38 | NA | |
| General population | ||||||||
| [ 31 ]Silva2011 | American population (4770) | Retrospective Portable level 2 PSG | 12.7 | RDI ≥15 | RDI<15 = 3822 | 948 | 345 | |
| Highway bus drivers | ||||||||
| [ 32 ]Firat2012 | Turkish population (85) | Prospective Lab PSG | 54.1 | AHI >15 | AHI<15 = 39 | 46 | NA | |
| Renal failure patients | ||||||||
| [ 33 ]Nicholl2013 | Canadian population (172) | Prospective Portable level 3 PSG | 42.4 | RDI ≥15 | AHI<15 = 99 | 73 | 50 | |