What may alter the conclusions of reviews?

Abstract

Background: four out of five selected review articles concluded that no evidence of effect from physiotherapy was found. We decided to assess their methodology and analyse how the selections made by the review authors affected the review conclusions.

Materials and methods: a new literature search was performed before the methodology of the review articles were assessed according to a list of nine validity criteria and 25 subcriteria.

Results: all five reviews were found to have methodological shortcomings. Prevalent methodological flaws were: incomplete literature search, inadequate validity assessment, sensitivity to change of inclusion criteria, errors in data synthesis and conclusions not adhering strictly to evidence. No review assessed if treatment procedure was adequately performed. All the reviews could have altered parts of their conclusions if the authors had made other relevant selections in the reviewing process.

Conclusion: poor methodological quality and selections made in the reviewing process can bias the conclusions in review articles on physiotherapy.

Keywords:

• BIAS
• METHODOLOGY
• PHYSIOTHERAPY
• REVIEW