Background: Realist review has been used to explain how and why complex health programmes are effective or not. However, this approach has not been extended to explaining the resource use, cost and cost-effectiveness of programmes or changes to services within the context of evidence synthesis. Some intervention mechanisms, their contexts and outcomes may be inherently resource-related, while others may have a behavioural focus and be harder to define in terms of resources— and therefore be harder to cost. The development and testing of more explanatory systematic review methods has been strongly advocated by the Campbell& Cochrane Economic Methods Group. We have been funded by the NIHR Service Delivery and Organisation programme (UK) to conduct a systematic review that summarises the evidence of the effectiveness and cost-effectiveness of 'step-down’, 'hospital at home’ and other forms of intermediate care that aim to provide an alternative to acute inpatient care.

Objectives: To present the methods (protocol) and early findings of this realist review, with a particular focus on the adaptation of methods for assessing and explaining the cost-effectiveness of intermediate care.

Methods: We will present the protocol for this review, describe any amendments to the planned methods, and reflect on the emerging challenges and insights from half-way through the 10-month project. Our intention is, as a first stage, to identify key intervention mechanisms and their related contexts which explain effectiveness, and then assess their resource requirements and opportunity costs as the second and third stages of analysis.

Results: The review protocol is in development and will be finalised by June 2011, preliminary findings will be available by October 2011.

Conclusions: On the basis of this review we will comment on how realist review methods may complement established Cochrane methods for systematic reviews of effectiveness.