Organizing is what you do before you do something, so that when you do it, it is not all mixed up. —AA Milne
*Mr. Ketterman's Case
I've read several articles now about exercise in patients with congestive heart failure. Some of them have very few subjects and they seem to have different results. How can I organize these results to help me make a decision about his care? (See Appendix for Mr. Ketterman's health history.)
Chapters 12, 13, and 14 have been concerned with the collection of data and its analysis from individual studies and their syntheses. These are forms of primary analysis. When trying to answer a clinical question with a limited amount of time and resources, it is common to focus on finding a few, or even only one, primary resource and therefore end up with an incomplete answer.
Most clinicians would feel more confident in applying research evidence if they could find complete and valid answers, and find them more efficiently. This is where what Haynes calls a synthesis of the relevant primary data is useful (Fig. 15-1).1,2 A synthesis, or secondary analysis, takes the form of a systematic review, where all the data on a topic is aggregated, with or without further statistical analysis, to gain a broader picture of the issue. This solves the clinician's problem of limited time and resources. It also addresses an issue frequently found in much of health care, where it is difficult to find large cohorts of subjects, and the resultant studies have a small number of participants (ns). Such studies individually do not provide sufficient information to guide practice. A synthesis has the advantage of collectively analyzing the results from these studies with a small number of subjects and identifying possible significant results that cannot be seen looking at one study at a time.
Sources of Information About Evidence. (Redrawn with permission from DiCenso A, Bayley L, Haynes RB. Accessing pre-appraised evidence: Fine-tuning the 5S model into a 6S model. Evid Based Nurs. 2009;12:99–101.)
This chapter will consider the systematic review, with and without a meta-analysis, as a way to quickly find answers to clinical questions. It will show you how to be a discerning reader of reviews and introduce you to methods commonly used to present the results. In addition, we will also discuss synopses of syntheses, Haynes's next level up the pyramid.
SYSTEMATIC REVIEWS AND META-ANALYSES
There is a long history of reviews in every discipline; these reviews are often based on the author's resources or preferences in selection of the articles to be reviewed. Often the review is designed from its inception to support a particular point of view. However, such reviews are ...