Failure of vital sign normalization is more strongly associated than single measures with mortality and outcomes.

BACKGROUND: Modified Early Warning Systems (MEWS) scores offer proxies for morbidity and mortality that are easily acquired, but there are limited data on what changing MEWS scores within the ED indicate. We examined the correlation of changing MEWS scores during resuscitation in the ED and in-hospital morbidity and mortality.
METHODS: We conducted a retrospective analysis on medical ED patients with simplified MEWS scores (without urine output or mental status) admitted to a single academic tertiary care center over one year. Triage-to-Last delta MEWS score and Triage-to-Max delta MEWS scores were calculated and correlated to in-hospital mortality, ICU admission, length of stay (LOS) and diagnosis of sepsis.
RESULTS: Our analysis included 8322 ED patients with an ICU admission rate of 17% and a mortality rate of 2%. Every point of worsened MEWS after triage was more strongly associated with all-cause mortality (OR 2.41, 95% CI 1.96-2.97) than triage MEWS alone (OR 1.33, 95% CI 1.23-1.44; p < 0.001). Likewise, each point of worsened MEWS was associated with increased odds of ICU admission (Triage-to-Last: OR 2.12, 95% CI 1.92-2.33 and Triage-to-Max: OR 1.52, 95% CI 1.45-1.60, respectively). Among patients with suspected infection, similar associations are found.
CONCLUSIONS: Dynamic vital signs in the emergency department, as categorized by delta MEWS, and failure to normalize abnormalities, were associated with increased mortality, ICU admission, LOS, and the diagnosis of sepsis. Our results suggest that MEWS scores that do not normalize, from triage onward, are more strongly associated with outcome than any single score.