Objectives Failure to recognise and respond to patient deterioration in an appropriate and timely manner has been highlighted as a global patient safety concern. Early Warning Scores (EWSs) using vital signs were introduced to address this concern, with the aim of getting the patient timely and appropriate treatment. The NEWS2 is in use across the NHS. While patient improvements have been shown, research has identified the NEWS2 is not always used as intended. Therefore, this review is using a realist approach to understand the mechanisms that influence the appropriate use (or not) of the NEWS2 in acute settings, taking into account; how, for whom and in which contexts. A programme theory (PT) is being developed to explain the role of the NEWS2 in the identification and management of deteriorating patients. On completion, recommendations will be made on how best to support the appropriate use of the NEWS2.

Method This review follows Pawson’s iterative six step process: One) Development of an initial PT. Two) Searching the literature. A systematic search was completed on: Cumulative Index to Nursing and Allied Health Literature (CINAHL), Medline, Embase (OvidSP), Web of Science (Science Citation Index and Social Science Citation), Cochrane Database of Systematic Reviews, Joanna Briggs Institute, Ethos, Proquest Dissertations and Theses Global, and Google Scholar for documents (1997 to 2022). Additional data was sourced via contacting authors, searching reference lists and citation-tracking. Inclusion criteria included all documents (including grey literature) that relate to the use of EWSs in the English only. Documents set in paediatric, maternity and primary care were excluded. Three) Selecting documents and quality appraisal. Four) Extracting and organising the data. Five) Synthesizing the data. Six) Disseminating the findings. A stakeholder group composed of clinicians who use the NEWS2 were recruited to provide feedback as the PT develops.

Results An initial PT (comprising of how the NEWS2 is intended (or unintended) to be used, i.e., from initial assessment of vital signs to review of the patient) was established via an exploratory scoping review and content expertise; and then discussed with stakeholders. The empirical testing of this PT will be against secondary research and grey literature. The documents retrieved from the searches have been screened against the inclusion/exclusion criteria; the initial analysis is currently in process to check the relevance and rigor of the data. Screened data will be used to help develop, refine or test the initial PT, pending its relevance and rigor. Any claims made on the plausibility of the programme theory will be based on both trustworthiness of data and coherence of arguments underpinning the PT. Preliminary findings will be available and presented at the time of conference.

Conclusions On conclusion, the review will identify how the NEWS2 may work well in one context, but not another, therefore, implementation may involve alterations in practice or policy based on the setting. The review will uncover the complex and inter-related elements of the PT; therefore, the stakeholder group will be consulted on how best to apply these insights to varied NHS settings and practice. Findings will be published in a peer-reviewed journal; and presented at relevant conferences. Accessible and user-friendly synopses of the findings will be shared with existing networks and on social media platforms.