Three key differences between realist reviews and qualitative evidence synthesis methods (eg, thematic synthesis, meta-ethnography)
| Area of difference | Realist reviews | Qualitative evidence synthesis methods | Example realist review |
| Theory driven | Produces programme theory to explain causation within a programme or intervention using context–mechanism–outcome configurations (CMOCs)* Theory may be used to inform data analysis | Developing theory is not necessarily a focus Theory may be used to inform data analysis | In a realist review on pharmacy-conducted medication reviews (MRs), nine CMOCs were incorporated into a programme theory to explain why, for whom, how and under which circumstances pharmacist-conducted MR succeed or fail to make differences to people’s health and healthcare utilisation after leaving hospital9 |
| Data sources | Any data source that contains relevant data may be included | Only data from qualitative research studies included | In a realist review on access to primary care, the programme theory was developed from 162 secondary data sources ranging of varying types (eg, cross-sectional, qualitative and cohort studies, as well as discussion papers)11 |
| Causation | Focused on explaining causation using the concept of generative causation:
| Explanation of causation not necessarily the focus of the review If there is a focus on causation, the type of causation and ontology on which it is based may be implicit | In a realist review that aimed to provide information on how safety-netting may be effectively communicated to reduce the risks to patient safety, 22 CMOCs were developed and embedded in a programme theory to explain how this may come about2 |
*See table 2 for a definition of CMOC.