Validation of EHMRG for Acute Heart Failure
What is the validity of the Emergency Heart Failure Mortality Risk Grade for 7-day (EHMRG7) and 30-day (EHMRG30-ST) mortality in patients with acute heart failure (AHF)?
The multicenter, prospective validation study of patients with AHF was conducted at nine hospitals in Ontario, Canada. The study authors excluded patients on dialysis or palliative care or had do not resuscitate (DNR) orders upon arrival. The authors surveyed physicians for their estimates of 7-day mortality risk, obtained for each patient prior to knowledge of the model predictions, and compared these with EHMRG7 for discrimination and net reclassification improvement. The physician responsible for emergency department (ED) disposition was required to estimate the probability that the patient would die within 7 days and enter their proposed management plan for the patient. They were required to enter their physician-estimated risk (PER) both as a percentage (from 0-100%) and as a category of risk: very low, low, intermediate, high, or very high risk. The investigators also prospectively examined discrimination of the EHMRG30-ST model, which incorporates all components of EHMRG7 as well as the presence of ST-depression on the 12-lead electrocardiogram. The primary outcome was death within 7 days after presentation to the emergency department. Mortality within 30 days after emergency presentation was a secondary outcome.
The study authors recruited 1,983 patients seeking ED care for AHF. There were 39 deaths at 7 days and 138 deaths (121 in-hospital and 17 out-of-hospital) at 30 days. Intubation or noninvasive positive pressure ventilation occurred in 83 (5.3%) hospitalized patients. Mortality rates at 7 days in the five risk groups; very low, low, intermediate, high, and very high risk, were: 0%, 0%, 0.6%, 1.9%, and 3.9% respectively. At 30 days, the corresponding mortality rates were: 0%, 1.9%, 3.9%, 5.9%, and 14.3%. Compared to physician-estimated risk of 7-day mortality (PER7, c-statistic, 0.71; 95% confidence interval [CI], 0.64-0.78), there was improved discrimination with EHMRG7 (c-statistic, 0.81; 95% CI, 0.75-0.87; p = 0.022 vs. PER7) and with EHMRG7 combined with physicians’ estimates (c-statistic, 0.82; 95% CI, 0.76-0.88, p = 0.003 vs. PER7). Model discrimination increased nonsignificantly, by 0.014 (95% CI, -0.009 to 0.037) when physicians’ estimates combined with EHMRG7 were compared to EHMRG7 alone (p = 0.242). The c-statistic for EHMRG30-ST alone was 0.77 (95% CI, 0.73-0.81) and 30-day model discrimination increased nonsignificantly by addition of physician-estimated risk to 0.78 (95% CI, 0.73-0.82, p = 0.187). Net reclassification improvement with EHMRG7 was 0.763 (95% CI, 0.465-1.062) when assessed continuously and 0.820 (0.560-1.080) using risk categories compared to PER7.
The authors concluded that when compared to physicians’ estimates, their multivariable model was better able to predict 7-day mortality.
This is an important study because it shows that EHMRG at 7 and 30 days is far superior to physician estimation of risk. As the authors point out, it would be important to validate these risk scores in a large multicenter prospective study of AHF, particularly in patients with accompanying renal dysfunction.
Keywords: Ambulatory Care, Depression, Electrocardiography, Emergency Service, Hospital, Geriatrics, Heart Failure, Hospital Mortality, Intubation, Palliative Care, Positive-Pressure Respiration, Renal Dialysis
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