Table 5

Risk of bias assessment

1. Randomised controlled trials
Cochrane Collaboration Tool Risk of bias items
Study (year)Sequence generationAllocationBlinding of participants and personnelBlinding of outcome assessmentOutcome dataSelective reportingOther threats to validity
Brooke16 (1992)UULLLLH
Mooney32 (1993)UULHLUH
Schneider42 (1999)UUUUHLH
Meythaler41 (2001)UULLUUH
Meythaler43 (2002)UUUULHH
Baños39 (2010)UULLLLH
Yablon33 (2010)UULLLUH
Giacino40 (2012)ULLLLLL
Hammond35 (2014)LLLLULL
Tramontana44 (2014)HHLLHLH
Johansson46 (2014)UHHHHLH
Beresford37 (2015)UULLHLH
Hammond17 (2015)LLLLULL
Fann45 (2017)LLLLLLH
Hart47 (2017)UULLLLL
2. Observational studies
Study (year)Newcastle-Ottawa Quality Assessment Scale
No of stars awarded
Rao50 (1985)****
Maturana Waidele38 (2009)****
Mysiw49 (2006)*****
Kooda51 (2015)****
Anderson48 (2016)****
Gramish36 (2017)****
  • For Cochrane Collaboration’s Tool: For Newcastle-Ottawa Quality Assessment Scale.

  • *Maximum four stars.

  • †Maximum two stars.

  • ‡Maximum  three stars.

  • H, high risk of bias; L, low risk of bias; U, unclear risk of bias.