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| TRIAL | Selection bias | Performance bias | Detection bias | Attrition bias |
| AGIS | A | D | A | A |
| Bergea 1992 | A | D | A | A |
| Blyth 1999 | B | D | B | A |
| Brancato 1991 | B | D | A | A |
| Chung 1998 | A | D | B | A |
| Damji 1999 | A | D | B | A |
| Elsas 1989 | B | D | B | B |
| EMGT | A | D | A | A |
| Gandolfi 2005 | B | D | B | A |
| GLT | A | D | A | A |
| Grayson 1993 | B | D | C | C |
| Grayson 1994 | B | D | C | C |
| Hugkulstone 1990 | B | D | A | C |
| Moorfields PTT | A | D | A | B |
| Moriarty 1988 | B | D | C | A |
| Rouhiainen 1988 | A | D | C | B |
| Sherwood 1987 | A | D | A | A |
| Smith 1984 | B | D | B | B |
| Watson 1984 | A | D | C | C |
