Abstract 332: Differences in Vital Signs Between Elderly and Non-Elderly Patients Prior to Ward Cardiac Arrest

Abstract

BACKGROUND: Vital signs and composite risk scores, such as the Modified Early Warning Score (MEWS), are used to identify high-risk patients, trigger rapid response teams, and assist with triage decisions. Although age-related vital sign changes are known to occur, little is known about the differences in vital signs between elderly and non-elderly patients prior to ward cardiac arrest (CA). We compared the accuracy of vital signs and the MEWS for detecting CA between elderly and non-elderly patients. METHODS: All patients hospitalized on the wards from five hospitals were included in the study. Patient characteristics and vital signs prior to CA were compared between elderly (age ≥65 years) and non-elderly (age <65 years) patients. The area under the receiver operating characteristic curve (AUC) was also calculated for vital signs and the MEWS for elderly and non-elderly ward patients for CA. RESULTS: A total of 269,956 admissions with documented age occurred during the study period, which included 422 index ward CAs. Within four hours of CA, elderly patients had significantly lower mean heart rate (88 vs. 99 beats per minute; P<0.001), diastolic blood pressure (60 vs. 66 mm Hg; P=0.007), and shock index (0.82 vs. 0.93; P<0.001), and higher pulse pressure index (0.45 vs. 0.41; P<0.001) and temperature (97.6 vs. 97.3 °F; P=0.047). The AUCs for all vital signs and the MEWS were higher for non-elderly patients than elderly patients (MEWS AUC 0.85 (95% CI 0.82-0.88) vs. 0.71 (95% CI 0.68-0.75); P<0.001). While the incidence of CA increased with age, accuracy of the MEWS decreased (Figure). CONCLUSIONS: Vital signs are much more accurate for detecting CA on the wards in non-elderly patients compared to elderly patients, which has important implications for how they are used for identifying critically ill patients. Further investigation into improving the accuracy of risk stratification for elderly patients is necessary in order to decrease their risk for this devastating event.