Methodological approaches in conducting overviews: current state in HTA agencies

Overviews search for reviews rather than for primary studies. They might have the potential to support decision making within a shorter time frame by reducing production time. We aimed to summarize available instructions for authors intending to conduct overviews as well as the currently applied methodology of overviews in international Health Technology Assessment (HTA) agencies.

We identified 127 HTA agencies and scanned their websites for methodological handbooks as well as published overviews as HTA reports. Additionally, we contacted HTA agencies by e-mail to retrieve possible unidentified handbooks or other related sources.

In total, eight HTA agencies providing methodological support were found. Thirteen HTA agencies were found to have produced overviews since 2007, but only six of them published more than four overviews. Overviews were mostly employed in HTA products related to rapid assessment. Additional searches for primary studies published after the last review are often mentioned in order to update results.

Although the interest in overviews is rising, little methodological guidance for the conduct of overviews is provided by HTA agencies. Overviews are of special interest in the context of rapid assessments to support policy-making within a short time frame. Therefore, empirical work on overviews needs to be extended. National strategies and experience should be disclosed and discussed.