11.5.2  Selecting outcomes for ‘Summary of findings’ tables

Cochrane reviews begin by developing a review question and by listing all main outcomes that are important to patients and other decision makers (see Chapter 5, Section 5.4) to ensure production of optimally useful information.  Consultation and feedback on the review protocol can enhance this process.

 

Important outcomes are likely to include widely familiar events such as mortality and major morbidity (such as strokes and myocardial infarction).  However, they may also represent frequent minor and rare major side effects, symptoms and quality of life, burdens associated with treatment, and resource issues (costs).  Burdens include the demands of adhering to an intervention that patients or caregivers (e.g. family) may dislike, such as having to undergo more frequent tests, or restrictions on lifestyle that certain interventions require.

 

Frequently, when formulating questions that include all patient-important outcomes for decision making, review authors will confront the fact that reports of randomized trials have not included all these outcomes.  This is particularly true for adverse outcomes.  For instance, randomized trials might contribute data on intended effects, and on frequent, relatively minor side effects, but not address the relative risk of rare adverse outcomes such as suicide attempts. Chapter 14 discusses strategies for adequately addressing adverse effects. To obtain data for all important outcomes it may be necessary to examine the results of observational studies. 

 

If a review includes only randomized trials, addressing all important outcomes may not be possible within the constraints of the review.  Review authors should acknowledge these limitations, and make them transparent to readers.

 

Review authors who take on the challenge of compiling and summarizing the best evidence for all relevant outcomes may face a number of challenges.  These include the fact that the analysis of harm may be carried out in studies whose participants differ from those included in the studies used in the analysis of benefit.  Thus, review authors will need to consider how much, if at all, the participants in observational studies differ from those in the randomized trials. This can influence the quality of evidence because of concerns about directness (see Chapter 12, Section 12.2). When review authors do not include information on these important outcomes in the review they should say so.  Further discussion of these issues appears also in Chapter 13.