In this study, 35.5% of the RRT-activated patients were transferred to the ICU. Patients admitted for medical reasons with an underlying chronic hepatobiliary disease or a higher SOFA score or NEWS score were more likely to be admitted to the ICU when RRT was activated. Patients admitted to the ICU had longer hospital LOS and higher 28-day in-hospital mortality rates. SOFA score, NEWS score, and platelet and lactate levels were associated with ICU transfer. ICU admission was not associated with in-hospital mortality.
RRT has been implemented in several hospitals to facilitate early recognition and treatment of deteriorating patients in wards [3, 8]. Most RRT activation leads to one or more interventions in patient, including additional diagnostic testing, obtaining a venous or central access line, applying oxygen, intubation, vasopressor use, or supporting cardiopulmonary resuscitation [3, 9, 10]. Interventions were often performed in patients admitted to the ICU in this study because they were more likely to have activated RRT due to septic shock, respiratory distress, and cardiogenic shock. Therefore, more interventions are thought to be required.
According to a recent review, RRT interventions have improved patient safety [2, 11]. RRT performance was generally measured in terms of heart attack, unexpected ICU hospitalization, and mortality [12]. Patients with RRT activation tended to have more ICU admissions and experienced a relatively high mortality rate [13]. The in-hospital mortality rate of RRT-activated patients was 23.5% in this study. The mortality rate has been variously confirmed, ranging from 10.6–42.2% [2, 5, 14, 15]. Several studies have shown that RRT intervention reduces mortality in hospitals [2, 3, 11, 16]. However, some studies have shown that RRT intervention did not affect mortality[9]. In the Medical Early Response Intervention and Therapy study [17], the medical emergency team system did not substantially affect cardiac arrest incidence, unplanned ICU admissions, or unexpected death. Maharaj et al. showed that RRS implementation was associated with an overall hospital mortality reduction in adult patients (relative risk [RR] 0.87, 95% CI 0.81–0.95, p < 0.001) and was also associated with a reduction in cardiopulmonary arrests in adults (RR 0.65, 95% CI 0.61–0.70, p < 0.001) [2]. Chan et. al. showed that RRT activation in adults was associated with a 33.8% reduction in cardiopulmonary arrest rates outside the ICU (RR 0.66, 95% CI, 0.54–0.80) but was not associated with lower hospital mortality rates (RR, 0.96; 95% CI, 0.84–1.09) [16]. Therefore, while these results remain controversial, a rapid response team can improve meaningful outcomes. Thus, understanding the group of patients admitted to the ICU and the prognosis can help increase RRT effectiveness.
In this study, high SOFA score, NEWS score, lactate level, and low platelet count were factors related to ICU admission. High SOFA score [18–20] and NEWS score [21, 22] are well-known factors related to patient severity. Higher scores indicate severe disease in patients; thus, it may have been associated with the patient's ICU admission. Lactate is known to be related to the severity of systemic hypoperfusion, and its high level is known to be associated with disease severity[23].
Acute deterioration after more than 7 days of hospitalization, septic shock was an independent risk factor for in-hospital mortality and ICU transfer [1, 24]. Age, screening for medical reasons, SOFA score, solid tumor, hematologic malignancy, T-bilirubin, lactate, and CRP were associated with in-hospital mortality in this study. Among these factors, SOFA score and lactate level are also related to the ICU admission factor. Therefore, more careful treatment when patients with these conditions are activated on RRT may help patients' prognosis.
This study had several limitations. First, this was a retrospective study performed at a single medical center. Second, the possibility of selection bias cannot be ruled out because many patients with missing variables were excluded. However, most of the missing variables were oxygen saturation or level of consciousness. This means that nurses did not use these variables for decision-making since the patients appeared to be mentally alert or did not require oxygen. Therefore, these patients may have had less severe disease and low in-hospital mortality risk. Third, since the RRT was not activated for 24 hours, the patient groups at the time when the RRT was not activated were not included in the study.