Systematic reviews explained: AMSTAR-how to tell the good from the bad and the ugly.

Systematic reviews are essential in summarising evidence and providing an indication of its strength and direction. This is why they often inform clinical decision making. Although the quantity of reviews published is increasing, concerns about their quality may sometimes be questioned. This paper highlights the aspects of systematic review methodology that influence a review's overall quality. The authors explain the recently developed tool "Assessment of Multiple Systematic Reviews" (AMSTAR) to demonstrate how this can be used efficiently, allowing a busy clinician to evaluate quality and decide whether or not a particular review should be used to inform their clinical practice. Systematic reviews may allow clinicians to incorporate the best available evidence into clinical practice. The ability to evaluate the quality and reliability of systematic reviews is imperative in this process. The authors have used items detailed in AMSTAR to demonstrate the aspects of systematic review methodology that influence the overall quality of a review.