Patient Safety Tip of the Week

July 15, 2014

Barriers to Success of

Early Warning Systems



We’ve done lots of columns on early warning scores (like MEWS, PEWS, and MEOWS) as tools to help in early recognition of patients with clinical deterioration. While the logic behind such scoring systems seems well-founded there has been a paucity of high-level evidence that such systems lead to substantial improvement in patient outcomes. Because of that and other factors, hospitals in the US have been very reluctant to adopt early warning scores into routine practice even as hospitals in the UK have been mandated to adopt such systems.


We’ve always been puzzled that something that seems so rational has failed to live up to its theoretical potential. But an excellent study just published in the nursing literature (Watson 2014) provides great insight into the barriers that impact implementation of an early warning system.


Watson and colleagues used a mixed methodology to evaluate factors related to their use of PEWS (the Pediatric Early Warning Score) at a children’s hospital. The methods included a retrospective review of VS (vital signs) and PEWS documentation, behavioral observations of RN activities related to patient assessment, and feedback from RN’s about workflow and their perception of PEWS.


Their chart review found a mean delay in charting of vital signs of 20 minutes for non-RN personnel (primarily patient care technicians) vs. 36.5 minutes for RN’s. They also found that there was poor consistency between charted vital signs (for heart rate and respiratory rate) and the numbers used in the PEWS. The behavioral observation demonstrated much multitasking by RN’s, most RN’s recorded patient assessments on paper and then used the paper when inputting assessments into the computer, and often used VS from monitors rather than from physical assessments. Bedside EMR charting occurred only 14% of the time.


The nurse feedback revealed that there were significant barriers to their concurrent charting: lack of computer availability or functionality, excess log-on times, and preferences for not charting in front of patients/family. RN’s also explained the discrepancy between charted VS and those used for PEWS in that they usually wanted to use their own assessments in the PEWS rather than the assessments done by the patient care techs. They also expressed their lack of confidence that the PEWS could detect deterioration above and beyond their own assessment skills.


Watson and colleagues suggest changes to the physical environment and improved technology interfaces to support real-time data entry as ways to improve usefulness of the PEWS. Beside computer access or use of smartphones or tablets for documentation would help. They also note that many EMR’s automatically populate VS into the early warning score tool. They also suggest examination of RN and non-RN tasks, perhaps returning VS assessment to RN’s so that data collection and documentation would be integrated. They felt it important to acknowledge the ambivalence RN’s had about the value of the PEWS and suggested adding RN concerns or family concerns to the criteria for the score.


Note that the latter (i.e. nurses felt the tool could not detect deterioration any better than they could) has been noted before. In fact, in our March 2012 What’s New in the Patient Safety World column “Value of an Expanded Early Warning System Scorewe noted that the expanded MEWS in a Netherlands study (Smith 2012) also used what we consider a most valuable measure: the nurse’s bedside gestalt of the patient’s condition!


This is an outstanding practical study which provides tremendous insight into why early warning scores have so far failed to demonstrate clearcut improvement in patient outcomes. It’s also a great example of how hospital-wide or system-wide implementation of a quality improvement intervention is likely to fail if we do not understand its impact on workflows and culture. Doing a pilot project first with the types of assessments done by Watson and colleagues would likely uncover many of the barriers they eventually found.



Some of our other columns on MEWS or recognition of clinical deterioration:







Watson A, Skipper C, Steury R, et al. Inpatient Nursing Care and Early Warning Scores: A Workflow Mismatch. J Nurs Care Qual 2014; 29(3): 215-222



Smith T, Den Hartog D, Moerman T, et al. Accuracy of an expanded early warning score for patients in general and trauma surgery wards. British Journal of Surgery 2012; 99: 192-197





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