Guide for Developing a Cochrane Protocol - Cochrane Public Health ...

measures will be selected when there are several possible measures (e.g. multiple definitions,
assessors or scales).
You should include all important outcomes in the protocol, even if you believe there will be
insufficient data present in the existing research to include in the synthesis. As well as potential
benefits, you must consider any potential adverse consequences of the intervention and ensure
that these are addressed in your review. Public health questions often have a large number of
outcomes of interest – we encourage authors to think carefully about what the main outcomes of
interest are likely to be for end-users. Once you have a complete list of the outcomes of interest,
you should identify a short list of main outcomes. The Cochrane Handbook suggests no more
than seven main outcomes should be chosen, however this should be examined on an individual
review basis. These outcomes will be used to summarise the key findings of your completed
review, for example in the abstract and Summary of Findings tables (if you include this in your
review). For some review questions, it may be appropriate to summarise findings for groups of
similar outcomes.
From among the main outcomes, select a small number of primary outcomes (usually 3 or less).
A primary outcome is of core interest to your review – i.e. the outcome that best answers your
effectiveness question. You should include at least one undesirable outcome (adverse effect),
known or hypothesised, with a rationale for why you think these may arise and why they are
important to include in the review.
All other main outcomes become secondary outcomes, along with any other additional outcomes
the review intends to address. These may include unintended outcomes that occur as a result of
the intervention. These are considered helpful in explaining intervention effects or the integrity
of the intervention. If you have a large number of secondary outcomes you should consider the
most appropriate ways of categorising these. If you are planning to include a Summary of
Findings table in your review (not compulsory but strongly recommended in The Cochrane
Handbook), you should state the outcomes you will be prioritising for this here.
For public health reviews, it may often be appropriate to include measures of changes in social
and environmental determinants of population health, as opposed to or in addition to direct
health outcomes. For example, changes in children’s purchasing habits (as a result of new
canteen policies in a school), and reduction in violent behaviour (as a result of adoption of
responsible drinking policies at a sports club).
You must clarify in advance whether any outcomes will be used as criteria for including studies
(rather than as a list of the outcomes of interest within included studies). Outcome measure
often do not necessarily form part of the criteria for including studies in a review, however some
reviews do legitimately restrict eligibility to specific outcomes. Furthermore, if relevant to your
topic, you may wish to specify requirements for the timing of outcome measurement, such as a
minimum period after the intervention before which an effect would not be detectable (e.g. the
effect of an intervention in pregnant women on the rate of babies born with low birth weight
could not be observable for several months after the intervention).
Resources
Cochrane Handbook – Chapters 4, 5, 13 and 21
Last updated: 24 November 2011 - 8 -