This present study is the first to compare ICU patients’ outcomes regarding their admission pathway: in or out-of-hospital. Despite the inherent bias of a single-center, retrospective study, its strengths include the strict comparability of its patients and their standardized management strategy. It concerns patients admitted for medical issues only and excludes patients with very specific ICU prognosis: elective surgical patients, severe trauma, intentional overdose and refractory cardiac arrests.
We found no difference in terms of hospital mortality between these two groups of emergencies while obvious differences describe them. IHE are more vulnerable patients. Indeed, they are older, characterized by much less independence in activities of daily living and more comorbidities, mainly immunosuppression and ongoing malignancy. IHE are mostly admitted for respiratory failures or shock. OHE patients are younger, have less comorbidities and are mostly admitted for cardiac arrest or coma caused by a hemorrhagic stroke. OHE suffer from more severe organ failures at presentation, have more lactic acidosis and more mechanical ventilation. In brief, our study brings out a similar mortality rate in both groups, highlighting more severe patients in the OHE group compared to the more vulnerable patients in the IHE group. Relating to IHE patients, our study underlines the importance of early ICU admission. Indeed, our results suggest that we manage these patients promptly, before they reach the severity of our OHE cohort. 8 IHE patients (12%) admitted to the ICU had already showed warning signs leading to a prior call from the ward. Severity scores and hospital mortality in this sub-group are much higher than those in patients immediately managed in ICU after a first call (SAPS II in “prior-call group”: 65 [53–82] vs. “first-call” group: 42 [36–59], p = 0.084; hospital mortality in “prior-call” group: 89% (n = 7) vs. “first-call” group: 36% (n = 23), p < 0.01). This data indicates that a delayed response may worsen patient outcome, as shown in a large studies (13,14).
In our study, hospital mortality in the two groups was high: 42% in the IHE group, 39% in the OHE group. A recent review of the literature shows an in-hospital mortality rate of 29% for IHE transferred to ICU. Studies from this review originated from many different countries and rates ranged from 7 to 35% (15). Another large Australian study reveals a hospital mortality rate of 35% in the same group of patients (16). In our study, the high median severity scores (SOFA: 7 [4–11] and SAPS II: 43 [36–64]) highlight the validity of an ICU admission. These elements either do not appear or are much lower (17) in other studies. Furthermore, our IHE patients are mostly medical patients. Medical category of admission is proven to be a major predictive factor of mortality in critically ill patients (18,19). Cultural differences, critical care capacity and resources, and whether critical care is deemed justified or futile have great influence on consequent results (20). One must be careful when interpreting such rates. As mentioned earlier, previous studies suggest that hospital mortality rates of patients admitted after RRT review were higher than the overall mortality rates (1–4). However, these studies took place at least 15 years ago, and RRS have improved. Tirkkonen et al. (15) suggest that ICU mortality rates of IHE patients are higher than the overall ICU mortality rates in recent multicentre studies (21,22), but no specific study was yet designed to compare in-hospital and out-of-hospital emergency outcomes.
This study reveals five independent risk factors for hospital mortality: SOFA and SAPS II score, hemorrhagic stroke as admission diagnosis, arterial lactate on ICU arrival, and ongoing malignancy. Our study confirms abundant evidence that lactate concentration is a predictor of mortality (23). The addition of lactate to ICU prognostication has been also shown to improve preexisting scores (24). The first four risk factors for hospital mortality found in our study are not useful decision-aid tools for ICU triage. Indeed, the MET or ICU physician do not initially know these four elements, when the patient’s admission needs to be decided. However, ongoing malignancy is a well-known independent risk factor for hospital mortality in critically ill patients (25,26). In line with recent data, in this population, hospital mortality increases tenfold. Even though new strategies of ICU admissions in cancer patients have been developed according to major recent advances in oncology, METs should bear in mind that ongoing malignancy is a key hospital mortality predictor. Along with age, it appears to be very useful for risk stratification of deteriorating patients in wards and determination of appropriate escalation of care. Our observations cannot be extrapolated to haematological malignancies as only solid cancer patients are represented in our study. Our results encourage strategies of time-limited trials of intensive care for critically ill patients with cancer. Indeed, after a 2 to 4-day trial, with the hindsight of initial severity scores and their progression, it seems appropriate to establish a joint assessment for re-evaluation of goals of therapy and level of care (27).