Table 1 Critical appraisal for methodological quality

Author name and year

Were the two groups similar and recruited from the same population?

Were the exposures measured similarly to assign people to both exposed and unexposed groups?

Was the exposure measured in a valid and reliable way?

Were confounding factors identified?

Were strategies to deal with confounding factors stated?

Were the groups/participants free of the outcome at the start of the study (or at the moment of exposure)?

Were the outcomes measured in a valid and reliable way?

Was the follow-up time reported and sufficient to be long enough for outcomes to occur?

Was follow-up complete, and if not, were the reasons for loss to follow-up described and explored?

Were strategies to address incomplete follow-up utilized?

Was appropriate statistical analysis used?

Score