Skip to main content

Table 4 Risk of bias for randomised studies using Cochrane risk of bias tool

From: An updated systematic review of interventions to increase awareness of mental health and well-being in athletes, coaches, officials and parents

Study

Random sequence generation

Allocation concealment

Blinding of participants and personnel

Blinding of outcome assessment

Incomplete outcome data

Selective reporting

Other bias

Summary

Ajilchi et al. (2019) [45]

cRandom draw

aRandomisation conducted by an independent party unconnected to project

cStudy was non-blinded

cStudy was non-blinded

aEach participant completed the intervention

aAll prespecified outcomes were reported

bAuthors transparent throughout. Small sample that is not diverse

High risk of bias for this study. Three domains showed a high risk of bias due to high risk of selection, detection and performance bias

Donohue et al. (2018) [47]

aUrn randomisation

bUnclear who performed randomisation

bNo measures described to blind participants to intervention

aAssessors from clinic that operated independently from intervention programmes. No blinds assessed to be broken.

aAnalyses adjusted for data being missing at random

aAll outcome measure effects were reported, along with effect sizes for each group

aStudy limitations addressed and transparency ensured throughout

Low risk of bias for this study. Two domains were unclear but they were unlikely to have had major bearing on results

Glass et al. (2019) [51]

aStratified random sampling to ensure comparable groups

bUnclear who performed randomisation

bParticipants were asked not to discuss details of intervention but it is possible discussion took place as participants were students at same university

bUnclear whether assessors had knowledge of treatment groups when assessing effects

cHigh attrition rate leaves data susceptible to attrition bias

aAll outcome measure effects were reported, along with effect sizes for each group

aStudy limitations were highlighted

Unclear risk of bias for this study. Aspects of selection, performance and detection bias were unclear. High risk of attrition bias due to nature of mindfulness intervention

Gross et al. (2018) [44]

cAttempt was made to use random selection but due to time constraints it was not employed, decision was taken to use one team.

bUnclear who performed randomisation into the two intervention groups

bParticipants were from the same team so there was potential for discussion about details of intervention

bUnclear whether assessors had knowledge of treatment groups when assessing effects

aAttrition and losses to follow-up were disclosed and reasons provided

aAll prespecified outcomes were reported

bPotential for allegiance effects influencing results as one of the groups was led by an author of the study but the study showed that therapeutic rapport did not have a significant effect

Unclear risk of bias for this study. Lack of randomisation raises prospect of selection bias but overall the process was transparent

Gulliver et al. (2012) [63]

aAutomated computer system used

aConditions allocated by researchers not involved in day-to-day management

aDescribed method used to reduce likelihood of participant knowledge of intervention

bUnclear whether assessors had knowledge of treatment groups when assessing effects

aAnalyses adjusted for data being missing at random

aAll outcome measure effects were reported, along with effect sizes for each group

aStudy limitations were addressed and caution is urged when interpreting significant effects

Low risk of bias for this study. One domain (blinding of outcome assessors) was unclear but it is unlikely if that influenced the results given the online format of the intervention and data collection

Liddle et al. (2019) [40]

aRandomisation occurred using a random number generator

aRandomisation conducted by an independent researcher not involved in intervention or data analysis

aParticipants not informed of allocated condition

bUnclear whether assessors had knowledge of treatment groups when assessing effects

aAnalyses adjusted for data being missing at random

aAll prespecified outcomes were reported

aAuthors were transparent about each stage of the intervention design

Low risk of bias for this study. One domain (blinding of outcome assessors) was unclear but it is unlikely to have significant impact on results

Sekizaki et al. (2019)

[55]

aRandomisation was performed using each student’s school number

bUnclear who performed randomisation

cStudy was non-blinded and in the same school there was risk for sharing of information between groups

cStudy non-blinded, potential for detection bias

aEach participant completed the intervention

aAll prespecified outcomes were reported

aStudy limitations were addressed and authors urged caution over the generalizability of the findings

Moderate risk of bias for this study. Selection, attrition and reporting bias risk was low. Risk of performance and detection bias was high due to no blinding.

Van Raalte et al. (2015) [69]

bMethod not disclosed

bUnclear who performed randomisation

bUnclear if participants were or were not blinded to their intervention

bUnclear whether assessors had knowledge of treatment groups when assessing effects

aAnalyses adjusted for data being missing at random

aAll outcome measure effects were reported, along with effect sizes for each group

aAuthors were transparent about each stage of the intervention design

Unclear risk of bias for this study. Information on selection, performance and detection bias was not disclosed, though attrition and reporting bias was low

Summary of bias across studies

Random sequence generation was performed in each study bar one. One study did not disclose method

Methods of allocation were largely unclear except for three studies where risk of bias was low

Blinding of participants was mixed, 4 studies were unclear while two had high risk and two low

The risk of bias was mixed, 5 studies were unclear while two had high risk and one low for blinding the assessors’ knowledge

7 of 8 studies displayed low risk of bias for controlling missing data, one study was high

There was a low risk of bias across the studies for reporting outcomes

Transparency was ensured by each of the studies, resulting in a low risk of bias for 6 studies and 2 unclear

Risk of selection, performance and detection bias findings were mixed. The risk for attrition and reporting bias was low with transparency maintained throughout each of the studies

  1. aLow risk of bias
  2. bUnclear risk of bias
  3. cHigh risk of bias