systematic reviews

The Cochrane Library contains more than 1,200 neurological systematic reviews. Click here for the Cochrane Neurological Network‘s Index of Diseases, which contains links to complete references for each neurological review. For the complete review, a subscription to the Cochrane Library is necessary.

Why do we need systematic reviews in neurology?

There are two primary reasons. First of all, there is so much information available that it is impossible to keep up with all of the developments in neurological care. For example, MEDLINE includes more than 500,000 articles about clinical trials in several neurological disease groups.

Secondly, the risk of bias should be eliminated. The most basic tool used for clinical research is the randomized controlled trial, which was developed specifically to reduce the risk of bias.

Knowledge-based health services require clinical, managerial and policy decisions that are based on sound information about research findings and scientific developments. High-quality, up-to-date systematic reviews of randomized controlled trials of healthcare interventions are of critical importance.

What makes systematic reviews work?

Traditionally, reviews have been written by experts in the field of medicine. Those experts may have strong opinions, which may factor into their conclusions. Systematic reviews reduce the risk of bias by:

• Using an explicit, detailed search strategy to find as many reports of relevant trials as possible
• Carrying out the review according to a written protocol
• Using explicit, pre-specified inclusion/exclusion criteria
• Using standard methods to assess trial quality
• Employing two people to independently extract the data
• Analyzing by synthesis of the actual numerical results whenever possible (also known as meta-analysis)
• Presenting the review in a detailed, clear and transparent fashion so readers can see how conclusions are reached

Systematic reviews often provide the best estimate of what the results of all relevant trials mean. This does not mean they can answer all of our questions. However, they do give us the best summary of current evidence that can be used when making individual treatment decisions or when developing new clinical trials.