Patients are primarily admitted to medical intermediate care units because of incipient or manifest organ failure. The main objective of this study has been to identify the conditions that have produced this organ failure and to investigate the short-term and long-term prognosis for this patient group. With a catchment area that encompasses nearly 10 % of Norway's population, our findings are likely to be generally valid and of value to hospitals that already have or are planning to establish a medical intermediate care unit.
In our study, the most frequent causes of admission were pneumonia and COPD exacerbation, the latter most likely caused by an infection. These were followed by sepsis, and infections were thus the dominant cause of admission. A high proportion of patients were admitted with poisonings, although many poisonings were treated in a ward with opportunities for telemetry. However, patients with poisonings admitted to intermediate care will need observation because of respiratory depression or a low level of consciousness.
The large number of patients with hyponatraemia in our study most likely represented an insufficient capacity for frequent blood tests/follow up in the wards, more than a need for medical intermediate care. At Akershus University Hospital, all patients with an s-Na below 120 mmol/l are considered for correction in an intermediate care unit.
With an average SAPS-II score of 34, the degree of seriousness of the acute illness was considerable. In comparison, Norwegian intensive care units as a whole had an average SAPS-II score of 38 in 2014 (6). A SAPS-II score of 34, however, is identical to the one found for intensive care units in local hospitals (6).
The populations were similar also in terms of age – the average age in medical intermediate care units was 64.2 years, compared to 65.5 years in intensive care units in local hospitals (6). There was a high degree of comorbidity, with 311 patients having a Charlson score ≥ 3, and approximately one-half of the cohort had a score ≥ 2.
Despite the fact that the degree of seriousness of the cause of admission was the same as the one reported from intensive care units in local hospitals, the hospitalisation time was shorter – median time was 1.25 days and the average 1.7 days, compared to a median time of 1.7 days and an average of 2.7 days (6). Efficient management and the fact that transfers to the wards were undertaken during the night is one possible explanation.
The proportion of readmissions amounted to 5.4 %, however, which is above the target of 4 %. The rate of readmissions to the intensive care unit, on the other hand, declined from 7.8 % in 2012 to 5.3 % in 2014 (6, 7). The reason may be that the medical intermediate care unit treats some patients that otherwise would have needed a bed in the intensive care unit, and that the intensive care unit transfers patients to intermediate care when they need beds. Only 5.5 % of the patients needed to be transferred to intensive care, indicating that many who are otherwise treated in intensive care units could have been attended to at a lower level of care.
The prognoses during and after a stay in medical intermediate care depended on the cause of admission. Patients with infections, congestive heart failure and restrictive/neuromuscular pulmonary disorders had the poorest prognoses, both while in hospital and after one year. Although infections are regarded as potentially transient and curable conditions and therefore given particular emphasis in prognostications and decisions on treatment restrictions, an infection was an independent predictor of hospital mortality in our population (Table 4).
The mortality observed after a stay caused by an infection was higher than would be expected in light of Charlson's index. Of those patients who had an infection or suspected infection and Charlson's index 0, altogether 11 % had died within one year. This is above average for the Charlson's index 0 group as a whole (6.4 %). Another study (8) also found higher mortality after a serious infection, which may be due to an underlying disease or that factors that predispose for infections also predispose for higher mortality.
There was no hospital mortality for patients who had been admitted for poisonings, but the one-year mortality rate of 5 % is disquieting and underscores the risk of early death in this patient group.
There was a significant difference in mortality among patients admitted from the ward and the emergency unit respectively. This tallies with findings made by a previous study of 53 % versus 30 % for patients admitted to an intensive care unit from a ward and an emergency unit respectively (9). The stay in intensive care was also significantly shorter for those who were admitted from the emergency unit.
Decompensation in the ward is an independent predictor of death (10, 11). The poorer prognosis for patients admitted from the ward may be due to the effect of delayed intervention. An alternative explanation is that the populations are different, and that patients hospitalised in wards are transferred to medical intermediate care because of a new condition or complication in addition to the disease for which they were primarily admitted.
The causes of admission that had the poorest prognoses in general were pneumonia, sepsis and congestive heart failure, but these diagnoses also had the greatest difference in mortality between admissions from the emergency unit and the ward respectively. These diagnoses may also involve complications for patients on a ward.
Using our source data and study design, we are unable to quantify the contributions made by different patient groups, new complications and delayed interventions, if any, to the difference in mortality observed in admissions from the emergency ward and the ward respectively. However, the difference in standardised mortality ratio was significant and indicates that in case of doubt as to whether a patient needs to be placed in medical intermediate care or not, the initial location ought to be intermediate care, rather than attempting the loop via a ward.
During the stay in intermediate care, 26 % of the patients had recorded a do-not-resuscitate and/or a do-not-intubate order. This decision was partly made on the ward or during a previous stay in a hospital/nursing home, but it was also made temporarily or situationally when attempting cardiopulmonary resuscitation was deemed useless at a critical treatment stage. We have no figures for the number of situationally dependent restrictions that were lifted after survival of a critical stage.
Altogether 35 % of the patients for whom treatment restrictions had been decided were still alive after one year. Thus, treatment restrictions do not necessarily mean that treatment has been abandoned; it is a decision made to spare the patient a meaningless treatment escalation or to ensure death with dignity. We cannot exclude the possibility, however, that the large number of patients with treatment restrictions is a reflection of overtreatment, and that too many patients with a previously recorded do-not-resuscitate order were accepted for advanced treatment in medical intermediate care.
We have little knowledge about mortality in medical intermediate care units in Norway, since this is a relatively new innovation and only few units exist. The mortality in Norwegian intensive care units, however, is documented through annual reporting to the Norwegian Intensive Care Registry (6, 12). Some of the reporting units are combined intermediate and intensive care units. Of all patients admitted to intensive care units in 2014 because of an acute medical condition, 19 % died during their hospitalisation (6). In comparison, hospital mortality in our cohort was 13 %.
In Europe, intermediate care units are increasingly being established in departments of internal medicine (13). In an observational study of 167 intensive care units in 17 European countries, the presence on an intermediate care unit in the hospital was associated with significantly lower mortality among patients admitted to the intensive care unit (14), and 25 % of the patients had used the intermediate care unit in connection with their stay in intensive care. Only few studies are available from other countries with comparable intermediate care units in departments of internal medicine that report epidemiological and mortality data. In a Spanish prospective observational study from an intermediate care unit in a department of internal medicine, the mortality rate was 7.8 % in the intermediate care unit and 14.1 % in the hospital (15), which concurs with our figures.
The strength of our study lies in its prospective design. In addition to the use of SAPS-II, comorbidity was rated with Charlson's index, the use of which has been recommended, but so far not published from Norwegian intensive care units (6). The registration is uniform and performed by a small number of persons associated with the unit. One weakness is that we cannot know whether the admission criteria are applied consistently at all hours of the day, and specialists associated with the unit in the daytime might possibly have rejected admissions that were accepted during the night. Moreover, the population is large and heterogeneous, with considerable variations in terms of diseases and prognoses.
Intermediate care units in departments of internal medicine may meet a need for surveillance and treatment of patients who are too ill for the ward, but who do not need to stay in intensive care. A combination of permanently employed specialists in internal medicine and anaesthesiologists in the unit provides good treatment outcomes.