Quality assessment based on the Critical Appraisal Skills Programme guidelines
| Author and date | Addressed a clearly focused issue | Appropriate method | Recruitment and comparability of study groups | Blinding | Exposure measurement | Outcome measurement | Follow-up | Confounding factors | Analysis | Results | Overall |
|---|---|---|---|---|---|---|---|---|---|---|---|
| Asimakopoulou (2008)20 | • | • | • | • | • | • | • | • | • | • | L |
| Avis (1989)21 | • | • | • | • | • | • | • | _ | • | • | L |
| Christensen (1995)22 | • | • | • | _ | • | • | • | • | • | • | L |
| Christensen (2004)23 | • | • | • | • | • | • | • | _ | • | • | L-M |
| Connelly (1998)24 | • | • | • | • | • | • | • | • | • | • | M-H |
| Hanlon (1995)25 | • | • | • | • | • | • | • | _ | • | • | M |
| Hussein (2008)26 | • | • | • | _ | • | • | • | • | • | • | M |
| Paterson (2002)27 | • | • | • | _ | _ | • | • | • | • | • | L |
| Persell (2013)28 | • | • | • | • | • | • | • | _ | • | • | M |
| Price (2011)29 | • | • | • | • | • | • | • | _ | • | • | M-H |
| Qureshi (2012)30 | • | • | • | • | • | • | • | • | • | • | M |
| Bucher (2010)31 | • | • | • | • | • | • | • | _ | • | • | H |
| Hall (2003)32 | • | • | • | • | • | • | • | • | • | M | |
| Hanon (2000)33 | • | • | • | • | • | • | • | _ | • | • | M |
| Grover (2007)34 | • | • | • | • | • | • | • | _ | • | • | M-H |
| Grover (2009)35 | • | • | • | • | • | • | • | _ | • | • | M |
| Lowensteyn (1998)36 | • | • | • | • | • | • | • | _ | • | • | M |
L, low; M, medium; H, high.