Table 2

Indicators of study quality

Quality indicatorArmon et al15Perlstein et al16Vasquez17Blair et al14Martinot et al18Gouin et al19Meates20
Was the objective of the study clearly described?YesYesYesYesYesYesYes
Are the main outcomes to be measured clearly described?YesYesYesYesYesYesYes
Are the characteristics of the included subjects clearly described?YesYesPartialNoPartialYesNo
Was there a clearly defined point in time when the intervention occurred?YesYesYesYesNAYesYes
Are the interventions of interest clearly described?YesYesYesYesYesPartialPartial
Are possible confounders clearly described?YesYesUnclearNoUnclearPartialNo
Are the main findings of the study clearly described?YesYesYesNoPartialYesYes
Are estimates of the random variability in the data provided?YesYesPartialPartialYesYesNo
Are all adverse events that may be a consequence of the intervention reported?UnclearUnclearUnclearUnclearUnclearUnclearUnclear
Are the characteristics of patients lost to follow-up described?YesUnclearUnclearNoUnclearUnclearUnclear
Were losses of patients to follow-up accounted for?YesUnclearUnclearNoUnclearUnclearUnclear
Are the actual probability values reported for the main outcomes?YesYesYesPartialYesYesNo
Were attempts made to blind outcome assessors to the intervention?NANANANoNANANA
Were the groups recruited from the same population?YesYesYesNoYesYesYes
Were the groups recruited over the same period of time?NoNoNoNoYesNoNo
Was the intervention independent of secular changes?YesYesYesNoYesNoYes
Was a representative sample of the population approached?YesYesUnclearPartialYesYesYes
Was the intervention unlikely to affect data collection?YesYesYesYesYesYesYes
Was the study adequately protected from contamination?YesYesYesUnclearYesYesYes
Was there reliable compliance with the intervention?YesNoUnclearNAYesYesYes
Were the main outcome measures used valid and reliable?YesYesYesYesYesYesYes
Was the study free from selective outcome reporting?YesYesYesUnclearUnclearYesUnclear
Were baseline characteristics similar between groups?YesPartialUnclearUnclearPartialYesUnclear
Were at least three data points recorded before and after the intervention?NoNoNANANANoNo
Were appropriate statistical tests used to assess the main outcomes?YesYesYesUnclearYesYesNo
Does the dataset cover more than 80% of the total number of episodes?YesYesUnclearNoYesYesYes
Were any results based on ‘data dredging’ identified as such?NANANANANANANA
Were adjustments made for different lengths of follow-up?NANANANANANANA
Was there adequate adjustment for confounding in the analysis?NAUnclearUnclearNoUnclearUnclearUnclear