Significantly Higher Mortality in Cardiogenic Shock Patients Transferred from an Outside Referring Facility Compared to Patients Presenting Initially to an Academic Medical Center

Abstract

Introduction Cardiogenic shock (CS) is a highly fatal condition characterized by cardiac dysfunction leading to inadequate tissue perfusion. Prior studies of STEMI-related CS patients have shown mortality rates approaching 50%. However, few studies have sought to clarify the rate of mortality among different patient populations hospitalized with this diagnosis, and none have investigated CS patients transferred for a higher level of care. We hypothesized that transferred patients would experience a higher mortality rate compared to inpatients initially admitted to an academic medical center. Methods The study population included patients hospitalized at an academic medical center with an ICD-9/10 discharge diagnosis of CS between 12/2015 and 8/2017. A chart review was performed to identify admission status: either initially to the academic medical center or transferred from a referring facility. Mortality was defined as death in the hospital or as a discharge to hospice. Baseline demographics, comorbid conditions, vital signs, echocardiographic data, hemodynamic and laboratory values were also obtained. Patient characteristics stratified by admission status were compared. Univariate and multivariate logistic regression analysis was performed to identify characteristics associated with mortality. All variables reported as significant had a two-sided p-value Results A total of 508 patients were included in this analysis. Patients were 62% male, 73% were Caucasian and mean age was 63 years. Presentation with STEMI was seen in 13%, ACS in 25% of patients and 31% of patients were transferred from another facility. Transferred patients had a higher rate of mortality than non-transfer patients (43.6% vs 33.5%, p=0.03). These patients were younger, had lower systolic blood pressure (SBP), higher heart rate, elevated troponin and were more likely to be in acute renal failure. Univariate predictors of mortality included admission post cardiac arrest, respiratory failure, acute renal failure or need for dialysis, lower SBP, elevated direct bilirubin, lactic acid and creatinine. Independent risk factors associated with mortality identified by multivariate regression analysis included admission post cardiac arrest, respiratory failure, need for dialysis and elevated lactic acid. Transfer status was not an independent predictor when adjusted for comorbidities. Conclusion Patients with CS transferred to an academic care center suffered a higher mortality rate than patients initially admitted to the academic center. Transferred patients are generally younger but represent a population with a higher severity of illness. While this explains the increased mortality observed in this group, it also indicates the need for early aggressive therapy for this population.