(HealthDay News) – Frequency of nighttime vital sign monitoring for low-risk medical inpatients may be reduced based on the evening Modified Early Warning Score (MEWS), according to a research letter published online July 1 in JAMA Internal Medicine.

Jordan C. Yoder, from the University of Chicago, and colleagues studied 54,096 consecutive adult inpatients at a 550-bed academic institution from Nov. 4, 2008, to Aug. 31, 2011. Electronic medical records were used to extract vital signs and a MEWS was calculated for each data set obtained on the general floors. Patients were stratified by MEWS most closely preceding 11PM. each evening. Across all MEWS categories, the authors compared the number of nighttime (11PM to 6AM) disruptions for vital sign monitoring and the occurrence of adverse events (intensive care unit transfers or cardiac arrests in the next 24 hours).

The researchers found that 1,699 adverse events occurred in the patient sample (43.0% male; median age, 56 years). The median evening MEWS was 2 and the adverse event rate significantly increased with higher evening MEWS, from a rate of 5.0 per 1,000 patient-days (when the MEWS was ≤1) to 157.3 per 1,000 patient-days (when the MEWS was ≥7). Regardless of MEWS category, the frequency of vital sign disruptions was unchanged, with a median of two vital sign checks per patient per night and at least one disruption from vital sign collection on 99.3% of the nights. Patients with a MEWS of ≤1 accounted for 45.0% of nighttime vital sign disruptions.

“The evening MEWS identified a low-risk subset of patients who had significantly fewer adverse events but had overnight vital signs taken at a similar rate as high-risk patients,” the authors write.

One author disclosed financial ties to Philips Healthcare, Laerdal Medical, and Quant HC.

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