Table 1 Glossary of terms

Context (C)

Context refers to the conditions in which the intervention operates. Context can refer to the individual taking part in the programme, or wider cultural, economic, and societal settings for programmes [28].

Mechanism (M)

Explains how an intervention works through defining underlying processes, which operate in contexts to produce certain outcomes. A mechanism includes the resources offered through an intervention (for example, help in an emergency) but also the individual’s reaction and response to these resources (for example, engagement and motivations from the individual) [29].

Outcome (O)

Outcome refers to the observed products following engagement with an intervention (intended or unintended) [26].

CMO configuration

A context-mechanism-outcome configuration (CMO) is a heuristic used to theorise how an intervention works, for whom and in what circumstances. CMOs may focus on a particular aspect of an intervention, or the intervention generally [30].

Initial programme theory (IPT)

IPT refers to potential ideas to how and why an intervention may work. IPTs will include potential contexts, mechanisms, and outcomes of interest to test in further empirical research.

Middle range theory (MRT)

MRT is a developed theory that can be used to explain the cause of outcomes for interventions. ‘Middle range’ means that the theory can be tested with observable data and is not theorising an abstract social force [26].

Programme theory

This explains how the intervention may work. In this review, individual CMO configurations represent individual programme theories, explaining specific components of the intervention. We also present an overarching programme theory, which summarises how telecare may work to support independent living in older adults.