Drawing conclusions about the practical usefulness of an intervention entails making trade-offs, either implicitly or explicitly, between the estimated benefits, harms and the estimated costs. Making such trade-offs, and thus making specific recommendations for an action, goes beyond a systematic review and requires additional information and informed judgements that are typically the domain of clinical practice guideline developers. Authors of Cochrane reviews should not make recommendations.
If authors feel compelled to lay out actions that clinicians and patients could take, they should – after describing the quality of evidence and the balance of benefits and harms – highlight different actions that might be consistent with particular patterns of values and preferences. Other factors that might influence a decision should also be highlighted, including any known factors that would be expected to modify the effects of the intervention, the baseline risk or status of the patient, costs and who bears those costs, and the availability of resources. Authors should ensure they consider all patient-important outcomes, including those for which limited data may be available. This process implies a high level of explicitness about judgements about values or preferences attached to different outcomes. The highest level of explicitness would involve a formal economic analysis with sensitivity analysis involving different assumptions about values and preferences; this is beyond the scope of most Cochrane reviews (although they might well be used for such analyses) (Mugford 1989, Mugford 1991); this is discussed in Chapter 15.
A review on the use of anticoagulation in cancer patients to increase survival (Akl 2007) provides an example for laying out clinical implications for situations where there are important trade-offs between desirable and undesirable effects of the intervention: “The decision for a patient with cancer to start heparin therapy for survival benefit should balance the benefits and downsides and integrate the patient’s values and preferences (Haynes 2002). Patients with a high preference for survival prolongation (even though that prolongation may be short) and limited aversion to bleeding who do not consider heparin therapy a burden may opt to use heparin, while those with aversion to bleeding and the related burden of heparin therapy may not.”