Table 1

Quality Assessment Tool for Quantitative Studies50

ComponentsStrongModerateWeak
Selection biasVery likely to be representative of the target population and ≥80% participation rateSomewhat likely to be representative of the target population and 60%–79% participation rateAll other responses or not stated
DesignRandomised controlled trial and CCTCohort analytic, case–control, cohort or an interrupted time seriesAll other designs or design not stated
ConfoundersControlled for at least 80% of confoundersControlled for 60%–79% of confoundersConfounders not controlled for, or not stated
BlindingBlinding of outcome assessor and study participants to intervention status and/or research questionBlinding of either outcome assessor or study participantsOutcome assessor and study participants are aware of intervention status and/or research question
Data collection methodsTools are valid and reliableTools are valid but reliability not describedNo evidence of validity or reliability
Withdrawals and drop-outsFollow-up rate of ≥80% of participantsFollow-up rate of 60%–79% of participantsFollow-up rate of <60% of participants or withdrawals and drop-outs not described

  • CCT, controlled clinical trial.