Table 2 Inclusion and exclusion criteria used in selecting studies for review

Empirical studies that:

a) use case study methodology, including as part of a wider study (e.g. RCT)

b) involve any health-related intervention that may be referred to as complex at the intervention or system level in any setting (e.g. hospitals, community)

c) involve any population/participants in any part of the world

d) focus on health care and related topics (e.g. information systems, management, public health interventions)

Other papers focused on case study and complex interventions that draw on empirical examples but are not original research papers.

Empirical studies that:

a) involve animals or were not on humans

b) are not published in English

c) cover specific topics (e.g. tourism, farming) and study types (e.g. cost-effectiveness models, protocols or simulations) that were not relevant to our review

d) do not evaluate an intervention

e) do not explicitly refer to use of case study design and/or methods or present ‘illustrative case studies’ (summarising a topic via a series of cases)

f) whole-country case studies (unless specific case studies of national-level institutions, e.g. departments of health, in which global health interventions were taking place)

g) protocols-only publications

Other papers presenting clinical case reports of single individuals.