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Table 1 Steps from existing systematic review frameworks and modifications needed (if relevant) to apply the steps to systematic reviews of prevalence studies of environmental and occupational risk factors to human health

From: Towards a framework for systematic reviews of the prevalence of exposure to environmental and occupational risk factors

Framework step

Modifications needed?

Specify research question

Yes – not usually a comparator, no outcome

Protocol

No – basic general step of systematic review

Systematic search

No – basic general step of systematic review

Defining eligibility criteria and screening studies

No – basic general step of systematic review

Data extraction

Yes – new data extraction categories and items are needed

Risk of bias assessment

Yes – risk of bias tools need to be adapted to prevalence study designs

Synthesis

Yes – meta-analyses need to account for ceilings and floors for prevalence and levels of exposure

Certainty of body of evidence assessment

Yes – certainty assessment frameworks need to be adapted for prevalence evidence