Table 2

Methodological quality of included studies (n=4), assessed on the Cochrane Collaboration’s Risk of Bias In Non-Randomised Studies tool

Ellingson et al43Flodin et al44Martinsen et al45Micalos et al46
1. Confounding
 1.1 Is there potential for confounding of the effect of intervention in this study?YesYesYesYes
 1.2 Was the analysis based on splitting participants’ follow-up time according to intervention received?NoNoNoNo
 1.4 Did the authors use an appropriate analysis method that controlled for all the important confounding domains?NoNoNoNo
 1.6 Did the authors control for any postintervention variables that could have been affected by the intervention?NoNoNoNo
2. Bias in selection of participants
 2.1 Was selection of participants into the study (or into the analysis) based on participant characteristics observed after the start of intervention?NoNoNoNo
 2.4 Do start of follow-up and start of intervention coincide for most participants?YesYesYesYes
3. Bias in classification of interventions
 3.1 Were intervention groups clearly definedYesYesYesYes
 3.2 Was the information used to define intervention groups recorded at the start of the interventions?YesYesYesYes
 3.3 Could classification of intervention status have been affected by knowledge of the outcome or risk of the outcome?YesYesYesYes
4. Bias due to deviations from intended interventions
 4.1 Were there deviations from the intended intervention beyond what would be expected in usual practice?NoNoNoNo
5. Bias due to missing data
 5.1 Were outcome data available for all, or nearly all, participants?YesYesYesYes
 5.2 Were participants excluded due to missing data on intervention status?NoYesYesNo
 5.3 Were participants excluded due to missing data on other variables needed for the analysis?NoNoNoNo
 5.4 Are the proportion of participants and reasons for missing data similar across interventions?N/ANoNoN/A
 5.5 Is there evidence that results were robust to the presence of missing data?N/ANoNoN/A
6. Bias in measurement of outcomes
 6.1 Could the outcome measure have been influenced by knowledge of the intervention received?NoNoNoNo
 6.2 Were outcome assessors aware of the intervention received by study participants?YesYesYesYes
 6.3 Were the methods of outcome assessment comparable across intervention groups?YesYesYesYes
 6.4 Were any systematic errors in measurement of the outcome related to intervention received?NoNoNoNo
7. Bias in selection of the reported result
 7.1 Is the reported effect estimate likely to be selected, on the baseis of the results, from multiple outcome measurements within the outcome domain?NoNoNoNo
 7.2 Is the reported effect estimate likely to be selected, on the basis of the results, from multiple analyses of the intervention–outcome relationship?NoNoNoNo
 7.3 Is the reported effect estimate likely to be selected, on the basis of the results, from different subgroups?NoNoNoNo
Overall risk of biasHighHighHighHigh
  • Items that were not applicable were omitted from this table.