Table 2

Quality assessment based on the Critical Appraisal Skills Programme guidelines

Author and dateAddressed a clearly focused issueAppropriate methodRecruitment and comparability of study groupsBlindingExposure measurementOutcome measurementFollow-upConfounding factorsAnalysisResultsOverall
Asimakopoulou (2008)20L
Avis (1989)21_L
Christensen (1995)22_L
Christensen (2004)23_L-M
Connelly (1998)24M-H
Hanlon (1995)25_M
Hussein (2008)26_M
Paterson (2002)27__L
Persell (2013)28_M
Price (2011)29_M-H
Qureshi (2012)30M
Bucher (2010)31_H
Hall (2003)32M
Hanon (2000)33_M
Grover (2007)34_M-H
Grover (2009)35_M
Lowensteyn (1998)36_M
  • L, low; M, medium; H, high.