Developing Modified Early Warning System Scores From the 2010 National Hospital Ambulatory Medical Care Survey

Background: Changes in patient vital signs may begin occurring as early as 8 – 12 hours prior to a cardiac arrest event. Clinicians have developed a variety of early warning systems (EWS) to alert nurses about physiological changes in patients. There is limited understanding about use of EWS in emergency departments (EDs). It is unknown if certain parameters could help predict outcomes and guide care on a large scale. The 2010 National Hospital Ambulatory Medical Care Survey (NHAMCS) is a large database containing data about patient visits to emergency departments (EDs). It was unknown if this data could be used to predict hospital admissions from EDs.

Aims: The purpose of this study was to determine if a Modified Early Warning System Score (MEWS) could be created for each patient in the NHAMCS dataset using vital signs recorded at admission and if the MEWS would predict inpatient admissions.

Methods: A literature search produced the body of knowledge to create and test a MEWS on a sample of 34, 936 adults from the 2010 NHAMCS. Multiple logistic regression analysis was performed, controlling for demographic variables.

Results: For every one-unit increase in MEWS, patients were 33% more likely to be admitted to the hospital. Females had lower risk of admission (19% less likely), whereas older adults were more likely to experience admissions. There was a 90% chance of inpatient admission with a MEWS of 13.

Conclusion: MEWS can be an early predictor of the need for hospitalization, potentially lowering risk for patients by early identification of the need for additional monitoring and care. Recommendations for practice include the adoption a MEWS in triage to establish a baseline score to follow the patient throughout the hospital stay. Educational implications include providing education to ED nurses on MEWS and how it can be utilized in the ED to detect declining patient status. Policy implications include considering MEWS as a nurse-driven protocol to enhance patient safety across the patient’s stay. Further research is needed about the prevalence of MEWS use in EDs in the United States and the relationship between MEWS and nursing triage scores.