Table 1.
Methodological quality assessment of included studies based on the Downs and Black checklist.
| First author, year | Reporting 0–10 |
External validity 0–3 |
Bias 0–7 |
Confounding 0–6 |
Power 0–5 |
Total 0–31 |
|---|---|---|---|---|---|---|
| Bonar,10 1993 | 5 | 1 | 2 | 2 | 0 | 10 |
| Crutchfield,11 1995 | 7 | 2 | 4 | 3 | 0 | 16 |
| Wyrsch,12 1996 | 8 | 1 | 5 | 4 | 0 | 18 |
| Anglen,13 1999 | 9 | 1 | 4 | 2 | 0 | 16 |
| Pugh,14 1999 | 7 | 2 | 4 | 2 | 0 | 15 |
| Bocchi,19 2000 | 7 | 1 | 5 | 3 | 0 | 16 |
| Watson,15 2000 | 9 | 1 | 4 | 3 | 0 | 17 |
| Harris,7 2006 | 9 | 2 | 4 | 2 | 0 | 17 |
| Koulouvaris,16 2007 | 9 | 2 | 5 | 3 | 0 | 19 |
| Bacon,17 2008 | 8 | 1 | 4 | 3 | 0 | 16 |
| Richards,18 2012 | 10 | 2 | 4 | 3 | 0 | 19 |
| Mean (SD) | 8 (1.4) | 1.5 (0.5) | 4.1 (0.8) | 2.7 (0.6) | 0.0 (0.0) | 16.3 (2.5) |