Table 1.

Observational prospective studies analysing factors associated with ICU admission or rejection.

Paper	Type of research	Study population	Aims	Outcomes	Limitations	Category
5	Prospective, observational cohort study of lung cancer inpatients with organ failure	140 Lung cancer patients with organ failure	To investigate factors associated with ITU admission in this population	Factors independently associated with ICU referral were performance status, nonprogressive malignancy and no explicit refusal of ICU admission by the patient and/or family. Factors independently associated with ICU admission were the initial ward being other than the lung cancer unit and an available medical ICU bed.		Referral and admission criteria objective
6	A single-centre, prospective, observational study was conducted among consecutive patients in whom an evaluation for ICU admission was requested during times of ICU overcrowding	95 Patients were evaluated for possible ICU admission during the study period	To investigate characteristics of patients accepted and declined for ITU admission in periods of overcrowding	Triage decisions were not related to the number of available beds in ICU, age or gender. A linear correlation was observed between severity of illness, expressed by APACHE-II scores and the likelihood of being admitted to ICU	American	Admission criteria objective
7	A single-centre, prospective, observational study of 165 consecutive triage evaluations	165 Consecutive triage evaluations	To assess factor in admission to ITU	Age, gender and number of ICU beds available at the time of evaluation were not associated with triage decisions		Admission criteria objective
8	Observational simulation study of physician decisions in patients’ admissions	100 Physicians given simulated patient cases	To assess decision making in admitting patients to ITU	Low agreement in decision-making, varies greatly for bed space availability and patient choices		Admission criteria objective
9	A single-centre, prospective, observational study of 572 consultations for ITU admission and decisions	572 ITU admission consultations were recorded	To assess the main factors in the decision to admit to ITU	Patients were less likely to be admitted if their functional baseline was poor and if a DNR was in place. Patients’ age, insurance, ethnicity, severity of illness, presence of malignancy or whether patient’s primary physician was on staff were not independently associated with admission	American, single centre	Admission criteria objective
10	An observational, prospective study over a six-month period of all adult patients triaged for admission to a medical ICU	398 Patients requested for ITU admission were assessed	To assess the factors associated with decisions to admit to ITU	Refusal of ICU admission was correlated with the severity of acute illness, lack of ICU beds and reasons for admission request	Morrocan, single centre	Admission criteria objective
11	Observational, prospective single-centre study of 100 referral to ITU decisions	100 Patients referred for ITU admission were assessed	To assess factors associated with decisions to admit to ITU and outcomes in those admitted versus not	Patients most likely to receive triage decisions were medical inpatients who had expressed wishes about end-of-life care, who were functionally limited with comorbid conditions or referred by junior doctor. Age, gender, race, diagnostic category, bed status and reason for referral did not impact on admission or triage decisions	Single centre	Admission criteria objective
12	Observational, prospective, multinational, multicentre study	8616 Patients referred for ITU admission were assessed	To assess factors associated with decisions to admit to ITU and outcomes in those admitted versus not	Variables positively associated with probability of being admitted to ICU included ventilators in ward; bed availability; Karnofsky score; absence of comorbidity; presence of haematological malignancy; emergency surgery and elective surgery (versus medical treatment); trauma, vascular involvement and liver involvement and acute physiological score II		Admission criteria objective
13	Cohort prospective study in a tertiary hospital	359 Patients referred for ITU admission were assessed	To assess factors associated with decisions to admit to ITU and outcomes in those admitted vs. not	Age, score system and organ dysfunctions were greater in priority groups 3 and 4, and these were related with refusal from the ICU		Admission criteria objective
14	Observational, prospective, single-centre study	250 Patients classified as triage priority 3 when referred for ITU admission were assessed	To identify factors associated with the triage decision for patients classified as Society of Critical Care Medicine (SCCM) Triage Priority 3	For triage 3 priority patients, medical patients were more likely to be rejected than surgical or neurosurgical patients. Those with a poorer physician-predicted chance of long-term survival were more likely to be rejected than those with a better predicted prognosis	Single centre	Admission criteria objective
15	Prospective, observational, single-centre study of factors influencing decisions in ITU admission	Data were collected on 179 patients referred for ITU admission	To assess factors associated with decisions to admit to ITU	The only factor that influenced MICU admission was the presence of DNR order. There was no difference between the age, APACHE II scores or functional status between admitted or refused		Admission criteria objective
16	Prospective, observational study in the medical ICU in a tertiary nonuniversity hospital	Cohort of 180 patients aged 80 years or over who were triaged for admission to ITU	To assess factors relating to admission to ITU in patients aged over 80 referred	Factors independently associated with refusal were nonsurgical status, age older than 85 years and full unit		Admission criteria objective age
17	Prospective, observational study of admission decisions for patients referred for ITU admission	356 Patients referred for ITU admission in University Hospital of the West Indies	To assess factors relating to admission to ITU in patients referred	The APACHE II score was the strongest predictor of ICU admission, with admission more likely as the score decreased. Of 311 requests considered suitable for admission, 26 (8%) were refused admission due to resource limitations	West Indies, single centre	Admission criteria objective
18	Observational, prospective, multiple-centre study	To identify factors associated with granting or refusing ICU admission	574 Patients from four university hospitals and seven primary-care hospitals in France	The reasons for refusal were too-well-to-benefit, too-sick-to-benefit, unit too busy and refusal by the family. Two patient-related factors were associated with ICU refusal: dependency and metastatic cancer. Other risk factors were organizational, namely, full unit, phone admission and daytime admission	French	Admission criteria objective and reasons given
19	National questionnaire survey using eight clinical vignettes involving hypothetical patients	To assess what factors influence doctors’ decisions about admission to ICU	232 Swiss doctors specialising in intensive care	Most rated as important or very important the prognosis of the underlying disease and of the acute illness and the patients’ wishes. Few considered important the socioeconomic circumstances of the patients’ religious beliefs and emotional state. In the vignettes factors associated with admission were patients’ wishes, ‘upbeat’ personality, younger age and a greater number of beds		Admission criteria objective and subjective
20	Prospective, observational study to assess factors influencing admission decisions, single-centre study	To assess the appropriateness of ICU triage decisions	334 patient admission decisions were assessed	Reasons for refusal were being too-sick-to-benefit and too-well-to-benefit. Factors independently associated with refusal were patient location, ICU physician seniority, bed availability, patient age, underlying diseases and disability	Single centre	Admission criteria objective and reasons given
21	Prospective, descriptive evaluation in a multi-disciplinary ICU, university referral hospital	To evaluate factors associated with decisions to refuse ICU admission	624 patient admission decisions were assessed	Refusal was associated with older age, diagnostic group and severity of illness	Single centre	Refusal criteria objective
22	Prospective, descriptive, single-centre study	To assess physician decision-making in triage for intensive care	382 patient admission decisions were assessed	Intensive care admission correlated with APACHE II score, age, a full unit, surgical status and diagnoses	Single centre	admission criteria objective

DNR: do not resuscitate; ICU: intensive care unit; MICU: medical intensive care unit; ITU: intensive therapy unit.