A systematic literature review of the National Early Warning Score (NEWS)-2 using Prediction Model Risk of Bias Assessment Tool (PROBAST)

Background

Identifying patients who are at risk of deteriorating to prevent avoidable complications is a challenge for health management. To support clinical decision-making, the UK introduced the National Early Warning Score 2 (NEWS-2). However, effectiveness in hospitals is not well understood.

Objective

To perform a systematic review of external validation studies of NEWS-2.

Methods

We performed a systematic review of NEWS-2 and a critical appraisal using PROBAST. Following PRISMA guidelines we searched Medline, Embase, Global Health and Social Policy and Practice for UK NEWS-2 external validation studies from January 2017 to November 2023. PROBAST was used to assess Risk-of-Bias (ROB), segmenting results by population level and model characteristics.

Results

31 validation studies were included in the final sample, including 19 from the UK, nine from Spain, one from Denmark and two from Sweden. 29 out of the 31 studies included were considered to have a high ROB with one having high risk of applicability. The main sources of bias were analytical weaknesses (n=29), outcome measures (n=8), weak inclusion/exclusion of participants (n=5) and weak predictors (n=2).

Conclusions

Most external validation studies of NEWS-2 have a high ROB. Future research is needed to address methodological weaknesses, particularly in predictors measurement, the inclusion of outcomes in the predictor measures, missing data, and inadequate calibration. These findings could help inform future Royal College of Physician’s (RCP) policy reviews of NEWS-2.

Registration

Not registered, the protocol was not prepared.

Guarantor of the work

Cidalia Eusebio

Social media abstract:

The high risk of bias in studies evaluating NEWS-2 means we should use caution not to rely on NEWS –2 alone for clinical decision making. #PatientSafety @eusebiocidalia @alisonleary1 @davidstuckler

Impact

• NEWS-2 was introduced in UK hospitals in 2017, but its effectiveness is unclear.

• We performed a critical appraisal of NEWS-2 in hospital and pre-hospital settings.

• Despite having a high ROB in the literature, NEWS-2 is utilised in the NHS.

• Clinicians should be cautious about relying solely on NEWS-2 for making decisions.

• Oxygen scores based on increase oxygen requirements should be reevaluated.

• This review supports reinstating the NEWS-2 policy review by the RCP, which was cancelled in 2023.

Reporting Method

We adhered to the relevant EQUATOR guidelines.

Patient or Public Contribution

There was no patient or public contribution.