In-Hospital Mortality in Cardiac Surgery Patients After Readmission to the Intensive Care Unit: A Single-Center Experience with 10,992 Patients Radoslaw Litwinowicz, MD, PhD, Krzysztof Bartus, MD, PhD, Rafal Drwila, MD, PhD, Boguslaw Kapelak, MD, PhD, Janusz Konstanty-Kalandyk, MD, PhD, Robert Sobczynski, MD, PhD, Karol Wierzbicki, MD, PhD, Magdalena Bartuś, MD, PhD, Anna Chrapusta, MD, PhD, Tomasz Timek, MD, PhD, Stanislaw Bartus, MD, PhD, Krzysztof Oles, MD, PhD, and Jerzy Sadowski MD, PhD Objectives: Determine if readmission to the intensive care unit (ICU) after cardiac surgery procedures is associated with increased mortality. Design: This was a retrospective non-randomized study to evaluate the cause of readmission and mortality rate in patients readmitted to the ICU after cardiac surgery and to compare the clinical variables of patients readmitted to the ICU who died and those who survived. Setting: The study was performed in a single university hospital. Participants: This was an analysis of 10,992 consecutive adult patients. Readmission rate to the ICU, mortality rate, the reason for readmission to the ICU, type of surgery, length of stay, cause of mortality, and day of the week of ICU readmission were analyzed. Interventions: All patients underwent cardiac surgery at a single center and were discharged after primary stay from the ICU. Measurements and Main Results: A total of 197 (1,8%) of 10,992 patients were readmitted to the ICU. In-hospital
mortality rate for patients readmitted and not readmitted to the ICU was 23.9% and 4.7%, respectively. The main causes of ICU readmission were cardiac (40%) and respiratory (37%) complications. The mortality rate in readmitted patients who underwent coronary artery bypass graft (CABG) or valve surgery was 26% and 19%, respectively. Conclusions: Patient readmission to the ICU following cardiac surgery was associated with a 5-fold increase in hospital mortality rate compared to non-readmitted patients. The highest mortality rate was observed among readmitted patients who underwent CABG. Older age, previous myocardial infarction, and initial long length of stay in the post-operative ward were independent risk factors for death after readmission to the ICU. & 2015 Elsevier Inc. All rights reserved.
P
surgery and to evaluate the influence of the type of cardiac surgery procedure on ICU readmission and subsequent mortality. Furthermore, the authors sought to determine the cause of readmission and assess the effect of the following on patient survival after readmission: Type of hospital admission, length of hospital stay, initial ICU and postoperative department stay, and day of the week (working days v non-working days) of admission or readmission to the ICU or to the postoperative department. To their knowledge, the current patient cohort represented the largest study population of postoperative cardiac surgery patients who were readmitted to the ICU.
ROPER CARE in the intensive care unit (ICU) after cardiac surgery is an integral part of effective treatment of cardiac patients. However, prolonged stay in the ICU is associated with increased mortality, morbidity, and worse longterm survival,1–3 and it increases the cost of treatment.4,5 Early discharge from the ICU, on the other hand, increases the risk of subsequent patient readmission to the ICU,6,7 which is associated with increased adverse outcomes compared with other types of ICU admissions.8,9 On average, patient readmission to the ICU after cardiac surgery procedures ranges from 2.3% to 5.9%.10–13 Unfortunately, there still is very limited literature available on this topic. Previous studies mainly have focused on etiology and risk factors for readmission, and most studies focused on selected groups of patients such as those after coronary artery bypass graft (CABG) or valve surgery. Currently, there are no studies that identify the predictors of mortality for cardiac surgery patients readmitted to the ICU. The aim of this study was to identify the risk factors for patient mortality after ICU readmission following cardiac
From the Jagiellonian University and John Paul II Hospital, Krakow, Poland. Drs. Radoslaw Litwinowicz and Krzysztof Bartus contributed equally to the preparation of this manuscript. Address reprint requests to Krzysztof Bartus, MD, PhD, Department of Cardiovascular Surgery and Transplantology, Jagiellonian University, and John Paul II Hospital, Ul. Pradnicka 80 31-202 Krakow, Poland. E-mail: [email protected] © 2015 Elsevier Inc. All rights reserved. 1053-0770/2601-0001$36.00/0 http://dx.doi.org/10.1053/j.jvca.2015.01.029 570
KEY WORDS: cardiac surgery, ICU mortality, mortality after cardiac surgery
METHODS
The authors conducted a retrospective analysis of 11,537 consecutive adult patients who underwent cardiac surgery procedures between January 1, 2009, and December 31, 2013, in a single, university-based cardiac surgery unit. Five hundred forty-five (4.7 %) patients who died in the operating room or during their initial stay in the ICU were excluded from the study. Patients who underwent heart transplantation (HTX) also were excluded. The remaining 10,992 patients who were discharged alive from the initial cardiac ICU admission were analyzed retrospectively. ICU Discharge Criteria The discharge of patients from the ICU to the postoperative ward was determined by the patient’s health status (as assessed by the Therapeutic Intervention Scoring System (score between 0 and 19 points; TISS-28) of cardiac surgical postoperative intensive care and by clinical judgment of the physician discharging the patient from the ICU. No fast-track or early extubation anesthetic techniques were used.
Journal of Cardiothoracic and Vascular Anesthesia, Vol 29, No 3 (June), 2015: pp 570–575
571
IN-HOSPITAL MORTALITY WITH ICU READMISSION
ICU Readmission Criteria and Definition “ICU readmission” was defined as a second ICU admission of a patient for a problem that was related directly to his/her primary admission and required close monitoring of his/her physical condition and vital functions. “Cause of readmission” was defined as all complications that were observed during the first 48 hours of ICU stay after readmission. The decision to transfer patients from the postoperative ward to the ICU was up to the discretion and clinical judgment of the ward physician and the physician readmitting the patient to the ICU. Study Databases Data for the study were obtained from medical records, hospital data, and the local KROK database (National Register of Cardiac Surgery). The following data were recorded: Age, gender, angina status, hypertension, diabetes, history of chronic lung disease (COPD), renal function, atrial fibrillation (AF), hyperlipidemia, history of stroke, extracardiac arteriopathy, urgency of the procedure (“urgent” was defined as a procedure performed o24 hours from the time of hospital admission), reoperation, active endocarditis, EuroSCORE, type of surgery, principal cause of readmission to the ICU, length of stay, and admission or readmission day of the week (weekends v weekdays). Patients readmitted to the ICU who died constituted group I, whereas readmitted patients who survived made up group II. In-hospital mortality rate of readmitted patients was compared with non-readmitted patients. Statistical Analysis Values are given as mean ⫾ standard deviation. The probability of an event given certain risk factors was calculated using logistic regression analysis, including odds ratio (OR) and its confidence interval (95% CI). A p value of less than 0.05 was considered statistically significant. Statistical analysis was performed using Statistica 10 software (StatSoft Inc., Tulsa, OK).
Table 1. Demographic, Perioperative, and Postoperative Patient Characteristics of Readmitted Patients n
Characteristic
Age [years] Female Male EuroSCORE CAD MI PCI Hypertension Diabetes type 2 COPD CKD AF Hyperlipidemia Extracardiac arteriopathy Previous cardiac surgery Active endocarditis Previous stroke Urgent ICU length of stay (day) Postoperative department admission Day Weekends Weekday Stay on postoperative department (day) ICU readmission day Weekends Weekday
68,18 ⫾ SD 10,89 35% 65% 6 ⫾ SD 3,12 54% 41% 19% 82% 31% 16% 23% 29% 53% 11% 9% 6% 9% 21% 5 ⫾ SD 7
— 69 128 — 106 80 38 161 61 31 46 58 104 21 18 12 18 21 —
86% 14%
170 27
6 ⫾ SD 7
—
76% 24%
150 47
Abbreviations: AF, atrial fibrillation; CAD, coronary artery disease; CKD, chronic kidney disease; COPD, chronic obstructive pulmonary disease; EuroSCORE, European System for Cardiac Operative Risk Evaluation; ICU, intensive care unit; MI, myocardial infarction; PCI, percutaneous coronary intervention.
Determinants of Mortality After Readmission
Causes of Readmission to the ICU, Types of Surgery, Mortality
Of the 197 patients (male 65%, female 35%) readmitted to the ICU, 47 (23.9%) patients died; these data are summarized in Figure 1. Only 7 patients out of 10,992 investigated patients were readmitted to the ICU directly from home or a nursing/ rehabilitation facility. Sixteen patients (8.1%) were discharged from the cardiac ICU to another hospital ICU for various reasons. These cases were not included in the authors’ survival analysis. Older age, myocardial infarction, and longer initial stay in the postoperative department were independent risk factors for patient death after readmission to the ICU (Table 4).
Thirty-six patients were readmitted to the ICU more than once. In these cases, the causes for first readmission were analyzed. Multiple complications were observed in 19 patients, and in these cases, all causes of readmission were analyzed. The most common causes of readmission to the ICU were cardiac (n ¼ 78/197, 40%) and respiratory (n ¼ 72/197, 37%) complications. The highest mortality rate was observed in patients readmitted with renal complications (46%). Mortality due to cardiovascular and respiratory complications was noted to be 31% and 22%, respectively. A complete summary of reasons for readmission and type of cardiac surgery is given in Table 3.
According to published data, there is a large variability of readmission rates to the ICU after cardiac surgery which range from 2.2% to nearly 8.75%.6,9,10,12–16 The rate of ICU readmission in the authors’ study was 1.8% and is the lowest in published literature. The higher readmission rates reported in the literature may be due to several underlying reasons. Firstly, these data come from different countries and cardiac surgery centers where different therapeutic methods and surgical protocols are used. Secondly, previous studies included only
RESULTS
Among 10,992 patients who underwent cardiac surgery during the study period and were discharged alive from the cardiac ICU, 197 (1.8%) required readmission to the ICU. The main demographic and perioperative patient characteristics are shown in Table 1. The highest readmission rate was 3.4% and was observed in patients after cardiac tumor surgery. A complete summary of readmission rates and type of cardiac surgery is given in Table 2.
DISCUSSION
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Table 2. Type of Surgery and Readmission to the ICU Readmitted patients Type of operation
CABG Standard CABG OPCAB Combine CABG þ Valve surgery CABG þ AVR CABG þ MVR CABG þ AVR þ MVR CABG þ ASD Valve surgery AVR MVR Mitral valvuloplasty TVR AVR þ MVR AVR þ TVR AVR þ MVR þ ASD MVR þ TVR MVR þ TVR þ VSD MVR þ TVR þ ASD AVR þ MVR þ TVR Aorta surgery Ascending aorta or aortic arch or aortic dissection Ascending aorta or aortic arch or aortic dissection þ MVR Yacoub operation Coarctation of the aorta Cardiac tumors Other TOTAL
N
111 90 4 17 11 3 2 1 63 31 10 5 4 5 1 1 2 1 2 1 13 10 1 1 1 3 7 197
(6,056) (5,403) (384) (653) (480) (142) (24) (ND) (2,740) (1.801) (401) (307) (33) (160) (13) (ND) (65) (ND) (ND) (19) (454) (406) (ND) (19) (ND) (89) (1653) (10 992)
Deaths after ICU readmissions %
N
%
1.8% 1.7% 1% 2.6% 2.3% 2.1% 8.3% — 2.3% 1.7% 2.5% 1.6% 12.1% 3.1% 7.7% — 3.1% — — 5.3 2.8% 2.5% — 5.3% — 3.4% 0.5% 1.8%
29 20 2 7 4 1 2 — 12 5 1 3 1 — — 1 1 — — — 2 2 — — — 2 2 47
26% 22% 50% 41% 36% 33% 100% — 19% 16% 10% 60% 25% — — 100% 50% — — — 15% 20% — — — 67% 29% 23.86%
Abbreviations: ASD, atrial septal defect; AVR, aortic valve replacement; CABG, coronary artery bypass graft; ICU, intensive care unit; MVR, mitral valve replacement; ND, no data; OPCAB, off-pump coronary artery bypass; TVR, tricuspid valve replacement; VSD, ventricular septal defect.
isolated CABG patients12,16 or CABG or valve replacement or combined CABG þ valve replacement procedures.10,11 The authors’ analysis was performed on all types of cardiac surgical procedures including patients on whom they operated due to an aortic aneurysm or acute aortic dissection, cardiac tumors, or other rarer diseases of the heart or great vessels. In the authors’ study, the readmission rate of patients after isolated CABG was 1.8% and after valve surgery was 2.3% and was similar10 or close to the findings of other studies.11,12,16 In recent years, the clinical profile of cardiac surgery patients has changed considerably. Currently, the number of minimally invasive procedures is rising, and, every year, new innovative solutions and procedures are developed. These treatments eliminate some complications and contribute to a faster recovery. As such, in modern cardiac surgery departments, in addition to cardiac surgery with cardiopulmonary bypass, minimally invasive procedures have become an integral part of the surgical workload. In the authors’ center, many innovative operations are performed17,18 that are not elsewhere classified, hence the large number of “other” operations in which the readmission rate was considerably lower (0.5%). It is noteworthy that the results of this study were based on a very large group of patients (10,992), with 197 readmissions allowing for a robust analysis, whereas previous studies included smaller patient cohorts.1,6,7,9,16
The most common causes of readmission in the authors’ study were cardiac complications present in 40% of patients, respiratory complications present in 37%, and tamponade presents in 15% of patients. In other studies, respiratory complications were the most common cause of readmission observed in 29.6% to 59% of patients,10–12 and cardiac complications were the second most common cause of readmission observed in 20% to 50% of patients. However, Benetis et al reported similar results to those observed in the authors’ study.16 Moreover, a recent large multicenter study conducted in 36 different ICUs found that cardiac complications were the primary etiology of patient readmission.19 The in-hospital mortality rate for patients readmitted to the ICU for any reason was 23.9% and was 5 times greater than that of non-readmitted patients (4.8%). Numerous studies performed in European cardiac surgery units were in accordance with these findings.13,16,20 These reports demonstrated mortality rates ranging from 17% to 36.4%, which were 2.8 to 11 times greater than in patients who were not readmitted to the ICU.10,13,16,20 Similarly, an Australian multicenter study19 showed that inhospital mortality in patients readmitted to the ICU was 20.7% and was 5 times greater than in non-readmitted patients (4.4%). The highest mortality rate in the authors’ study was noted in patients who underwent cardiac tumor removal (67%). However, due to a small number of readmitted patients, these results had lower clinical significance. The mortality in patients
573
IN-HOSPITAL MORTALITY WITH ICU READMISSION
Table 3. Type of Cardiac Surgery and Principal Causes and Mortality of Readmission of Patients to the Cardiac ICU All procedures (n ¼ 197)
Cardiovascular Arrhythmia Bradycardia SCA Asystole No data Bradycardia PEA Ventricular fibrillation Cardiogenic pulmonary edema Acute right ventricular failure Shock Myocardial infarction Low-cardiac-output syndrome No clear etiology Respiratory ARDS Noncardiogenic pulmonary edema Pneumothorax Exacerbation of COPD Pneumonia Pleural hematoma Pulmonary embolism No clear etiology Sternal drainage with bony instability Tamponade Renal AKI-1 AKI-2 AKI-3 Exacerbation of CKD Neurologic Stroke Loss of consciousness Other Hypoglycemia Gastrointestinal bleeding Mesenteric arterial embolism Psychosis Sepsis Exacerbation of liver cirrhosis Paravalvular leakage Acute mitral regurgitation
M
CABG (n ¼ 94)
E
%
78 4 1 39 10 9 1 7 12 3
40% 2% 1% 20% 5% 5% 1% 4% 6% 2%
24 31% 36 1 1 100% 1 13 33% 17 4 40% 5 5 56% 3 1 1 4 33% 7 1
38% 1% 1% 18% 5% 3% 1% 1% 7% 1%
1
1%
1
1%
4 1 5
2% 1% 3%
2 1 1
2% 1% 1%
20 72 1 6
10% 8 40% 13 14% 4 37% 16 22% 34 35% 8 1% 0% 3% 3 3%
2 13 17 1 1 31 8
1% 7% 9% 1% 1% 16% 4%
2% 4% 6% 1% 0% 11 35% 18 19% 1 13% 6 6%
29 13 1 7 4 1 7 6 1 14 1 3 1
15% 7% 1% 4% 2% 1% 4% 3% 1% 7% 1% 2% 1%
5 17% 9 6 46% 8 1 100% 2 29% 6 2 50% 2 1 100% 3 43% 2 3 50% 1 1 2 14% 9 1 2 1
4 2 1
2% 1% 1%
1
2 1
1% 1%
2
1 4
%
40%
8% 24%
25%
E
%
2 4 6 1
3 2
M
%
1 non-CABG (n ¼ 59) E
10 28% 21 1 1 100% 5 29% 14 1 20% 3 2 67% 6
2
29%
2 3 1
%
M
%
E
2 procedures
Z3 procedures
(n ¼ 21)
(n ¼ 9)
%
M
E
%
36% 6 2%
29% 8 38% 5 2 10%
24% 4 5% 1 10% 2
29% 4 3 100% 1 11% 33% 2 10% 2 100% 33% 1
3% 5% 2%
33%
M
63% 4 44% 2
(n ¼ 13) %
E
%
M
%
50% 5 38% 1
20%
0%
33%
2 10% 1
3 23% 1
2 15% 0% 1 8% 1 100% 1 8%
1 11%
1 8% 1
2%
3 33% 2
31% 5 8% 2 24% 22 37% 6 2
3%
5 5
8% 8%
40% 2 10% 2 100% 27% 8 38% 2 22% 1
25% 17%
2
4 19% 40% 2 10%
6 1
33% 10 17% 4 17% 1 2%
40% 1 5% 1 5%
9% 8%
2 3
22% 12 20% 2 38% 4 7% 2
17% 3 14% 1 50%
6% 2%
2 1
33% 50%
2% 1% 1% 9% 1% 2% 1% 1
67%
50% 5 38% 1 1 8%
20%
1 5%
1 1
3% 2%
%
Aorta Surgery
2 22% 1
50% 2 15% 1 8% 2 15% 1
33% 2 22%
1 2 1 3 3
2% 3% 2% 5% 5%
1 50% 1 100% 1 33% 1 33%
2 22% 2 100% 2 22% 2 100%
3
6%
1
2 22%
1
2%
33%
33%
50%
3 23% 1 8% 1 100% 1 8% 1 100%
1 8% 1
2%
1
2%
2 22% 1 100%
1 100%
Abbreviations: AKI, acute kidney injury; ARDS, acute respiratory distress syndrome; CABG, coronary artery bypass graft; CKD, chronic kidney disease COPD, chronic obstructive pulmonary disease; E, events; ICU, intensive care unit; M, mortality; PEA, pulseless electrical activity; SCA, sudden cardiac arrest.
readmitted to the ICU after CABG (26%) was 7.4 times greater than in non-readmitted patients who underwent CABG (3.5%). The mortality rate in patients readmitted to the ICU after valve surgery was 19%.
Apart from 100% mortality after acute mitral regurgitation (1 case), the highest mortality rate for readmission etiology was observed with renal insufficiency (46%) and neurologic injury (43%). In this aspect, the current work represented the
574
LITWINOWICZ ET AL
Fig 1.
In-hospital mortality in patients requiring and not requiring ICU readmission.
first study to analyze the relation between the cause of readmission and in-hospital mortality. Etiology and risk factors for readmission to the ICU are well-described in the cardiac surgery literature; however, the
Table 4. Multivariate Logistic Regression Analysis of Risk Factors of Death After Readmission to the ICU
Variable
Age EuroSCORE Female Coronary artery disease MI PCI Hypertension Diabetes type 2 COPD Chronic kidney disease Atrial fibrillation Hyperlipidemia Extracardiac arteriopathy Previous cardiac surgery Active endocarditis Stroke Surgery on thoracic aorta Surgery required within o24 h ICU length of stay (days) Day of admission to postoperative department (weekend) Stay on postoperative department before readmission Day of readmission to ICU (weekend)
Odds Ratio (OR)
95% Confidence Interval for OR
p Value
0,91 0,98 1,04 0,78 3,10 0,85 1,68 0,754 0,97 0,80 0,80 2,34 0,42 11,23 1,41 1,27 1,68 1,68 1,0 0,87
0,87-0,96 0,85-1,13 0,43- 2,55 0,30-2,01 1,12-8,58 0,29-2,49 0,58-4,87 0,29-1,95 0,29-3,21 0,31-2,06 0,77-5,50 0,99-5,55 0,12-1,47 0,93-135,99 0,24-8,37 0,34-4,72 0,27-10,31 0,27-10,32 0,95-1,05 0,27-2,81
0,001 0,079 0,92 0,60 0,03 0,77 0,33 0,56 0,97 0,65 0,66 0,052 0,17 0,055 0,70 0,72 0,57 0,21 0,91 0,81
0,91
0,83-0,99
0,028
0,59
0,29-1,54
0,28
Abbreviations: COPD, chronic obstructive pulmonary disease; ICU, intensive care unit; MI, myocardial infarction; PCI, percutaneous coronary intervention.
determinants of patient mortality after readmission have not been described. The authors’ multivariate logistic regression showed that older age, previous myocardial infarction, and longer initial stay in the postoperative department were independent risk factors for mortality after ICU readmission. Clinical variables including sex, hypertension, diabetes, COPD, CKD, stroke, hyperlipidemia, extracardiac arteriopathy, previous cardiac surgery, previous PCI, or EuroSCORE did not significantly increase mortality after readmission. However, it should be noted that readmitted patients were characterized by a high incidence of elevated EuroSCORE values (eg, mean EuroSCORE values 6 ⫾ 3.1). Moreover, prior studies have shown that these variables are associated strongly with higher probability for ICU readmission,1,3,6,7,9,16,20 which is associated with higher mortality, morbidity, and surgical risk. For that reason, the authors suggest that the previously listed variables increase the risk of readmission but do not increase the mortality of readmitted patients. Type of hospital admission, type of surgery, and length of stay also are well-known risk factors of mortality and morbidity of patients readmitted to the ICU.21,22 In cardiac surgery patients, the length of initial stay in the ICU is one of the strongest risk factors for readmission to the ICU.10–12 However, the influence of the urgency of the operative procedure (elective v urgent) on readmission rates differed among studies. Benetis et al16 suggested that urgent surgery is a risk factor for ICU readmission in patients with cardiac complications, while Bardell and colleagues12 refuted these findings. In the authors’ analysis, they found no evidence that length of stay or surgery status had any impact on mortality in patients who were readmitted to the ICU. Some studies also suggested that admissions to the ICU on a weekend or after “working hours” (weekdays v weekend) was associated with increased hospital mortality.23 However, the “weekend effect” as a risk factor for ICU readmission never has been evaluated in detail. The authors’ study, based on nearly 11,000 thousand patients, revealed that the day of admission to the postoperative department or the day of readmission to the ICU had no impact on mortality rates.
575
IN-HOSPITAL MORTALITY WITH ICU READMISSION
The effect of length of stay in the postoperative ward on ICU readmission has not been reported in previously published studies although it may influence readmission mortality. The authors’ data revealed that mean length of stay in the postoperative cardiac surgery department was longer in patients readmitted to the ICU who subsequently died than in readmitted patients who survived the stay. CONCLUSIONS
This large, single-center study found that 1.8% of patients undergoing various types of cardiac surgery procedures were
readmitted to the ICU. Patient readmission to the ICU increased the in-hospital mortality rate 5 times compared to non-readmitted patients. The main causes of patient readmission to the ICU were cardiac and respiratory complications. The highest mortality rate of patients readmitted to the ICU was observed among patients who underwent CABG surgery. Older age, previous myocardial infarction, and long length of stay in the postoperative ward were identified as independent risk factors for patient death after readmission to the ICU.
REFERENCES 1. Bashour CA, Yared JP, Ryan TA, et al: Long-term survival and functional capacity in cardiac surgery patients after prolonged intensive care. Crit Care Med 28:3847-3853, 2000 2. Cunnion KM, Weber DJ, Broadhead WE, et al: Risk factors for nosocomial pneumonia: Comparing adult critical-care populations. Am J Respir Crit Care Med 153:158-162, 1996 3. Légaré JF, Hirsch GM, Buth KJ, et al: Preoperative prediction of prolonged mechanical ventilation following coronary artery bypass grafting. Eur J Cardiothorac Surg 20:930-936, 2001 4. Chalfin DB, Cohen IL, Lambrinos J: The economics and costeffectiveness of critical care medicine. Intensive Care Med 21: 952-961, 1995 5. Oye RK, Bellamy PE: Patterns of resource consumption in medical intensive care. Chest 99:685-689, 1991 6. Kogan A, Cohen J, Raanani E, et al: Readmission to the intensive care unit after “fast-track” cardiac surgery: Risk factors and outcomes. Ann Thorac Surg 76:503-507, 2003 7. Cohn WE, Sellke FW, Sirois C, et al: Surgical ICU recidivism after cardiac operations. Chest 116:688-692, 1999 8. Elliott M, Worrall-Carter L, Page K: Intensive care readmission: A contemporary review of the literature. Intensive Crit Care Nurs 30: 121-137, 2014 9. Joskowiak D, Wilbring M, Szlapka M, et al: Readmission to the intensive care unit after cardiac surgery: A single-center experience with 7105 patients. J Cardiovasc Surg (Torino) 53: 671-676, 2012 10. Vohra HA, Goldsmith IR, Rosin MD, et al: The predictors and outcome of recidivism in cardiac ICUs. Eur J Cardiothorac Surg 27: 508-511, 2005 11. Litmathe J, Kurt M, Feindt P, et al: Predictors and outcome of ICU readmission after cardiac surgery. Thorac Cardiovasc Surg 57: 391-394, 2009 12. Bardell T, Legare JF, Buth KJ, et al: ICU readmission after cardiac surgery. Eur J Cardiothorac Surg 23:354-359, 2003
13. Giakoumidakis K, Eltheni R, Patelarou A, et al: Incidence and predictors of readmission to the cardiac surgery intensive care unit: A retrospective cohort study in Greece. Ann Thorac Med 9:8-13, 2014 14. Toraman F, Senay S, Gullu U, et al: Readmission to the intensive care unit after fast-track cardiac surgery: An analysis of risk factors and outcome according to the type of operation. Heart Surg Forum 13: E212-E217. 15. Celkan MA, Ustunsoy H, Daglar B, et al: Readmission and mortality in patients undergoing off-pump coronary artery bypass surgery with fast-track recovery protocol. Heart Vessels 20:251-255. 16. Benetis R, Sirvinskas E, Kumpaitiene B, et al: A case-control study of readmission to the intensive care unit after cardiac surgery. Med Sci Monit 19:148-152, 2013 17. Bartuś K, Sadowski J, Kapelak B, et al: Denervation of nerve terminals in renal arteries: one-year follow-up of interventional treatment of arterial hypertension. Kardiol Pol 72:425-431, 2014 18. Bartus K, Han FT, Bednarek J, et al: Percutaneous left atrial appendage suture ligation using the LARIAT device in patients with atrial fibrillation: Initial clinical experience. J Am Coll Cardiol 62:108-118, 2013 19. Renton J, Pilcher DV, Santamaria JD, et al: Factors associated with increased risk of readmission to intensive care in Australia. Intensive Care Med 37:1800-1808, 2011 20. Jarząbek R, Buajski P, Greberski K, et al: Readmission to an intensive care unit after cardiac surgery: Reasons and outcomes. Kardiol Pol 72:740-747, 2014 21. Kramer AA, Zimmerman JE: Predicting outcomes for cardiac surgery patients after intensive care unit admission. Semin Cardiothorac Vasc Anesth 12:175-183, 2008 22. Kaben A, Corrêa F, Reinhart K, et al: Readmission to a surgical intensive care unit: Incidence, outcome and risk factors. Crit Care 12: R123, 2008 23. Bhonagiri D, Pilcher DV, Bailey MJ: Increased mortality associated with after-hours and weekend admission to the intensive care unit: A retrospective analysis. Med J Aust 194:287-292, 2011
mortality rate for patients readmitted and not readmitted to the ICU was 23.9% and 4.7%, respectively. The main causes of ICU readmission were cardiac (40%) and respiratory (37%) complications. The mortality rate in readmitted patients who underwent coronary artery bypass graft (CABG) or valve surgery was 26% and 19%, respectively. Conclusions: Patient readmission to the ICU following cardiac surgery was associated with a 5-fold increase in hospital mortality rate compared to non-readmitted patients. The highest mortality rate was observed among readmitted patients who underwent CABG. Older age, previous myocardial infarction, and initial long length of stay in the post-operative ward were independent risk factors for death after readmission to the ICU. & 2015 Elsevier Inc. All rights reserved.
P
surgery and to evaluate the influence of the type of cardiac surgery procedure on ICU readmission and subsequent mortality. Furthermore, the authors sought to determine the cause of readmission and assess the effect of the following on patient survival after readmission: Type of hospital admission, length of hospital stay, initial ICU and postoperative department stay, and day of the week (working days v non-working days) of admission or readmission to the ICU or to the postoperative department. To their knowledge, the current patient cohort represented the largest study population of postoperative cardiac surgery patients who were readmitted to the ICU.
ROPER CARE in the intensive care unit (ICU) after cardiac surgery is an integral part of effective treatment of cardiac patients. However, prolonged stay in the ICU is associated with increased mortality, morbidity, and worse longterm survival,1–3 and it increases the cost of treatment.4,5 Early discharge from the ICU, on the other hand, increases the risk of subsequent patient readmission to the ICU,6,7 which is associated with increased adverse outcomes compared with other types of ICU admissions.8,9 On average, patient readmission to the ICU after cardiac surgery procedures ranges from 2.3% to 5.9%.10–13 Unfortunately, there still is very limited literature available on this topic. Previous studies mainly have focused on etiology and risk factors for readmission, and most studies focused on selected groups of patients such as those after coronary artery bypass graft (CABG) or valve surgery. Currently, there are no studies that identify the predictors of mortality for cardiac surgery patients readmitted to the ICU. The aim of this study was to identify the risk factors for patient mortality after ICU readmission following cardiac
From the Jagiellonian University and John Paul II Hospital, Krakow, Poland. Drs. Radoslaw Litwinowicz and Krzysztof Bartus contributed equally to the preparation of this manuscript. Address reprint requests to Krzysztof Bartus, MD, PhD, Department of Cardiovascular Surgery and Transplantology, Jagiellonian University, and John Paul II Hospital, Ul. Pradnicka 80 31-202 Krakow, Poland. E-mail: [email protected] © 2015 Elsevier Inc. All rights reserved. 1053-0770/2601-0001$36.00/0 http://dx.doi.org/10.1053/j.jvca.2015.01.029 570
KEY WORDS: cardiac surgery, ICU mortality, mortality after cardiac surgery
METHODS
The authors conducted a retrospective analysis of 11,537 consecutive adult patients who underwent cardiac surgery procedures between January 1, 2009, and December 31, 2013, in a single, university-based cardiac surgery unit. Five hundred forty-five (4.7 %) patients who died in the operating room or during their initial stay in the ICU were excluded from the study. Patients who underwent heart transplantation (HTX) also were excluded. The remaining 10,992 patients who were discharged alive from the initial cardiac ICU admission were analyzed retrospectively. ICU Discharge Criteria The discharge of patients from the ICU to the postoperative ward was determined by the patient’s health status (as assessed by the Therapeutic Intervention Scoring System (score between 0 and 19 points; TISS-28) of cardiac surgical postoperative intensive care and by clinical judgment of the physician discharging the patient from the ICU. No fast-track or early extubation anesthetic techniques were used.
Journal of Cardiothoracic and Vascular Anesthesia, Vol 29, No 3 (June), 2015: pp 570–575
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IN-HOSPITAL MORTALITY WITH ICU READMISSION
ICU Readmission Criteria and Definition “ICU readmission” was defined as a second ICU admission of a patient for a problem that was related directly to his/her primary admission and required close monitoring of his/her physical condition and vital functions. “Cause of readmission” was defined as all complications that were observed during the first 48 hours of ICU stay after readmission. The decision to transfer patients from the postoperative ward to the ICU was up to the discretion and clinical judgment of the ward physician and the physician readmitting the patient to the ICU. Study Databases Data for the study were obtained from medical records, hospital data, and the local KROK database (National Register of Cardiac Surgery). The following data were recorded: Age, gender, angina status, hypertension, diabetes, history of chronic lung disease (COPD), renal function, atrial fibrillation (AF), hyperlipidemia, history of stroke, extracardiac arteriopathy, urgency of the procedure (“urgent” was defined as a procedure performed o24 hours from the time of hospital admission), reoperation, active endocarditis, EuroSCORE, type of surgery, principal cause of readmission to the ICU, length of stay, and admission or readmission day of the week (weekends v weekdays). Patients readmitted to the ICU who died constituted group I, whereas readmitted patients who survived made up group II. In-hospital mortality rate of readmitted patients was compared with non-readmitted patients. Statistical Analysis Values are given as mean ⫾ standard deviation. The probability of an event given certain risk factors was calculated using logistic regression analysis, including odds ratio (OR) and its confidence interval (95% CI). A p value of less than 0.05 was considered statistically significant. Statistical analysis was performed using Statistica 10 software (StatSoft Inc., Tulsa, OK).
Table 1. Demographic, Perioperative, and Postoperative Patient Characteristics of Readmitted Patients n
Characteristic
Age [years] Female Male EuroSCORE CAD MI PCI Hypertension Diabetes type 2 COPD CKD AF Hyperlipidemia Extracardiac arteriopathy Previous cardiac surgery Active endocarditis Previous stroke Urgent ICU length of stay (day) Postoperative department admission Day Weekends Weekday Stay on postoperative department (day) ICU readmission day Weekends Weekday
68,18 ⫾ SD 10,89 35% 65% 6 ⫾ SD 3,12 54% 41% 19% 82% 31% 16% 23% 29% 53% 11% 9% 6% 9% 21% 5 ⫾ SD 7
— 69 128 — 106 80 38 161 61 31 46 58 104 21 18 12 18 21 —
86% 14%
170 27
6 ⫾ SD 7
—
76% 24%
150 47
Abbreviations: AF, atrial fibrillation; CAD, coronary artery disease; CKD, chronic kidney disease; COPD, chronic obstructive pulmonary disease; EuroSCORE, European System for Cardiac Operative Risk Evaluation; ICU, intensive care unit; MI, myocardial infarction; PCI, percutaneous coronary intervention.
Determinants of Mortality After Readmission
Causes of Readmission to the ICU, Types of Surgery, Mortality
Of the 197 patients (male 65%, female 35%) readmitted to the ICU, 47 (23.9%) patients died; these data are summarized in Figure 1. Only 7 patients out of 10,992 investigated patients were readmitted to the ICU directly from home or a nursing/ rehabilitation facility. Sixteen patients (8.1%) were discharged from the cardiac ICU to another hospital ICU for various reasons. These cases were not included in the authors’ survival analysis. Older age, myocardial infarction, and longer initial stay in the postoperative department were independent risk factors for patient death after readmission to the ICU (Table 4).
Thirty-six patients were readmitted to the ICU more than once. In these cases, the causes for first readmission were analyzed. Multiple complications were observed in 19 patients, and in these cases, all causes of readmission were analyzed. The most common causes of readmission to the ICU were cardiac (n ¼ 78/197, 40%) and respiratory (n ¼ 72/197, 37%) complications. The highest mortality rate was observed in patients readmitted with renal complications (46%). Mortality due to cardiovascular and respiratory complications was noted to be 31% and 22%, respectively. A complete summary of reasons for readmission and type of cardiac surgery is given in Table 3.
According to published data, there is a large variability of readmission rates to the ICU after cardiac surgery which range from 2.2% to nearly 8.75%.6,9,10,12–16 The rate of ICU readmission in the authors’ study was 1.8% and is the lowest in published literature. The higher readmission rates reported in the literature may be due to several underlying reasons. Firstly, these data come from different countries and cardiac surgery centers where different therapeutic methods and surgical protocols are used. Secondly, previous studies included only
RESULTS
Among 10,992 patients who underwent cardiac surgery during the study period and were discharged alive from the cardiac ICU, 197 (1.8%) required readmission to the ICU. The main demographic and perioperative patient characteristics are shown in Table 1. The highest readmission rate was 3.4% and was observed in patients after cardiac tumor surgery. A complete summary of readmission rates and type of cardiac surgery is given in Table 2.
DISCUSSION
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Table 2. Type of Surgery and Readmission to the ICU Readmitted patients Type of operation
CABG Standard CABG OPCAB Combine CABG þ Valve surgery CABG þ AVR CABG þ MVR CABG þ AVR þ MVR CABG þ ASD Valve surgery AVR MVR Mitral valvuloplasty TVR AVR þ MVR AVR þ TVR AVR þ MVR þ ASD MVR þ TVR MVR þ TVR þ VSD MVR þ TVR þ ASD AVR þ MVR þ TVR Aorta surgery Ascending aorta or aortic arch or aortic dissection Ascending aorta or aortic arch or aortic dissection þ MVR Yacoub operation Coarctation of the aorta Cardiac tumors Other TOTAL
N
111 90 4 17 11 3 2 1 63 31 10 5 4 5 1 1 2 1 2 1 13 10 1 1 1 3 7 197
(6,056) (5,403) (384) (653) (480) (142) (24) (ND) (2,740) (1.801) (401) (307) (33) (160) (13) (ND) (65) (ND) (ND) (19) (454) (406) (ND) (19) (ND) (89) (1653) (10 992)
Deaths after ICU readmissions %
N
%
1.8% 1.7% 1% 2.6% 2.3% 2.1% 8.3% — 2.3% 1.7% 2.5% 1.6% 12.1% 3.1% 7.7% — 3.1% — — 5.3 2.8% 2.5% — 5.3% — 3.4% 0.5% 1.8%
29 20 2 7 4 1 2 — 12 5 1 3 1 — — 1 1 — — — 2 2 — — — 2 2 47
26% 22% 50% 41% 36% 33% 100% — 19% 16% 10% 60% 25% — — 100% 50% — — — 15% 20% — — — 67% 29% 23.86%
Abbreviations: ASD, atrial septal defect; AVR, aortic valve replacement; CABG, coronary artery bypass graft; ICU, intensive care unit; MVR, mitral valve replacement; ND, no data; OPCAB, off-pump coronary artery bypass; TVR, tricuspid valve replacement; VSD, ventricular septal defect.
isolated CABG patients12,16 or CABG or valve replacement or combined CABG þ valve replacement procedures.10,11 The authors’ analysis was performed on all types of cardiac surgical procedures including patients on whom they operated due to an aortic aneurysm or acute aortic dissection, cardiac tumors, or other rarer diseases of the heart or great vessels. In the authors’ study, the readmission rate of patients after isolated CABG was 1.8% and after valve surgery was 2.3% and was similar10 or close to the findings of other studies.11,12,16 In recent years, the clinical profile of cardiac surgery patients has changed considerably. Currently, the number of minimally invasive procedures is rising, and, every year, new innovative solutions and procedures are developed. These treatments eliminate some complications and contribute to a faster recovery. As such, in modern cardiac surgery departments, in addition to cardiac surgery with cardiopulmonary bypass, minimally invasive procedures have become an integral part of the surgical workload. In the authors’ center, many innovative operations are performed17,18 that are not elsewhere classified, hence the large number of “other” operations in which the readmission rate was considerably lower (0.5%). It is noteworthy that the results of this study were based on a very large group of patients (10,992), with 197 readmissions allowing for a robust analysis, whereas previous studies included smaller patient cohorts.1,6,7,9,16
The most common causes of readmission in the authors’ study were cardiac complications present in 40% of patients, respiratory complications present in 37%, and tamponade presents in 15% of patients. In other studies, respiratory complications were the most common cause of readmission observed in 29.6% to 59% of patients,10–12 and cardiac complications were the second most common cause of readmission observed in 20% to 50% of patients. However, Benetis et al reported similar results to those observed in the authors’ study.16 Moreover, a recent large multicenter study conducted in 36 different ICUs found that cardiac complications were the primary etiology of patient readmission.19 The in-hospital mortality rate for patients readmitted to the ICU for any reason was 23.9% and was 5 times greater than that of non-readmitted patients (4.8%). Numerous studies performed in European cardiac surgery units were in accordance with these findings.13,16,20 These reports demonstrated mortality rates ranging from 17% to 36.4%, which were 2.8 to 11 times greater than in patients who were not readmitted to the ICU.10,13,16,20 Similarly, an Australian multicenter study19 showed that inhospital mortality in patients readmitted to the ICU was 20.7% and was 5 times greater than in non-readmitted patients (4.4%). The highest mortality rate in the authors’ study was noted in patients who underwent cardiac tumor removal (67%). However, due to a small number of readmitted patients, these results had lower clinical significance. The mortality in patients
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IN-HOSPITAL MORTALITY WITH ICU READMISSION
Table 3. Type of Cardiac Surgery and Principal Causes and Mortality of Readmission of Patients to the Cardiac ICU All procedures (n ¼ 197)
Cardiovascular Arrhythmia Bradycardia SCA Asystole No data Bradycardia PEA Ventricular fibrillation Cardiogenic pulmonary edema Acute right ventricular failure Shock Myocardial infarction Low-cardiac-output syndrome No clear etiology Respiratory ARDS Noncardiogenic pulmonary edema Pneumothorax Exacerbation of COPD Pneumonia Pleural hematoma Pulmonary embolism No clear etiology Sternal drainage with bony instability Tamponade Renal AKI-1 AKI-2 AKI-3 Exacerbation of CKD Neurologic Stroke Loss of consciousness Other Hypoglycemia Gastrointestinal bleeding Mesenteric arterial embolism Psychosis Sepsis Exacerbation of liver cirrhosis Paravalvular leakage Acute mitral regurgitation
M
CABG (n ¼ 94)
E
%
78 4 1 39 10 9 1 7 12 3
40% 2% 1% 20% 5% 5% 1% 4% 6% 2%
24 31% 36 1 1 100% 1 13 33% 17 4 40% 5 5 56% 3 1 1 4 33% 7 1
38% 1% 1% 18% 5% 3% 1% 1% 7% 1%
1
1%
1
1%
4 1 5
2% 1% 3%
2 1 1
2% 1% 1%
20 72 1 6
10% 8 40% 13 14% 4 37% 16 22% 34 35% 8 1% 0% 3% 3 3%
2 13 17 1 1 31 8
1% 7% 9% 1% 1% 16% 4%
2% 4% 6% 1% 0% 11 35% 18 19% 1 13% 6 6%
29 13 1 7 4 1 7 6 1 14 1 3 1
15% 7% 1% 4% 2% 1% 4% 3% 1% 7% 1% 2% 1%
5 17% 9 6 46% 8 1 100% 2 29% 6 2 50% 2 1 100% 3 43% 2 3 50% 1 1 2 14% 9 1 2 1
4 2 1
2% 1% 1%
1
2 1
1% 1%
2
1 4
%
40%
8% 24%
25%
E
%
2 4 6 1
3 2
M
%
1 non-CABG (n ¼ 59) E
10 28% 21 1 1 100% 5 29% 14 1 20% 3 2 67% 6
2
29%
2 3 1
%
M
%
E
2 procedures
Z3 procedures
(n ¼ 21)
(n ¼ 9)
%
M
E
%
36% 6 2%
29% 8 38% 5 2 10%
24% 4 5% 1 10% 2
29% 4 3 100% 1 11% 33% 2 10% 2 100% 33% 1
3% 5% 2%
33%
M
63% 4 44% 2
(n ¼ 13) %
E
%
M
%
50% 5 38% 1
20%
0%
33%
2 10% 1
3 23% 1
2 15% 0% 1 8% 1 100% 1 8%
1 11%
1 8% 1
2%
3 33% 2
31% 5 8% 2 24% 22 37% 6 2
3%
5 5
8% 8%
40% 2 10% 2 100% 27% 8 38% 2 22% 1
25% 17%
2
4 19% 40% 2 10%
6 1
33% 10 17% 4 17% 1 2%
40% 1 5% 1 5%
9% 8%
2 3
22% 12 20% 2 38% 4 7% 2
17% 3 14% 1 50%
6% 2%
2 1
33% 50%
2% 1% 1% 9% 1% 2% 1% 1
67%
50% 5 38% 1 1 8%
20%
1 5%
1 1
3% 2%
%
Aorta Surgery
2 22% 1
50% 2 15% 1 8% 2 15% 1
33% 2 22%
1 2 1 3 3
2% 3% 2% 5% 5%
1 50% 1 100% 1 33% 1 33%
2 22% 2 100% 2 22% 2 100%
3
6%
1
2 22%
1
2%
33%
33%
50%
3 23% 1 8% 1 100% 1 8% 1 100%
1 8% 1
2%
1
2%
2 22% 1 100%
1 100%
Abbreviations: AKI, acute kidney injury; ARDS, acute respiratory distress syndrome; CABG, coronary artery bypass graft; CKD, chronic kidney disease COPD, chronic obstructive pulmonary disease; E, events; ICU, intensive care unit; M, mortality; PEA, pulseless electrical activity; SCA, sudden cardiac arrest.
readmitted to the ICU after CABG (26%) was 7.4 times greater than in non-readmitted patients who underwent CABG (3.5%). The mortality rate in patients readmitted to the ICU after valve surgery was 19%.
Apart from 100% mortality after acute mitral regurgitation (1 case), the highest mortality rate for readmission etiology was observed with renal insufficiency (46%) and neurologic injury (43%). In this aspect, the current work represented the
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LITWINOWICZ ET AL
Fig 1.
In-hospital mortality in patients requiring and not requiring ICU readmission.
first study to analyze the relation between the cause of readmission and in-hospital mortality. Etiology and risk factors for readmission to the ICU are well-described in the cardiac surgery literature; however, the
Table 4. Multivariate Logistic Regression Analysis of Risk Factors of Death After Readmission to the ICU
Variable
Age EuroSCORE Female Coronary artery disease MI PCI Hypertension Diabetes type 2 COPD Chronic kidney disease Atrial fibrillation Hyperlipidemia Extracardiac arteriopathy Previous cardiac surgery Active endocarditis Stroke Surgery on thoracic aorta Surgery required within o24 h ICU length of stay (days) Day of admission to postoperative department (weekend) Stay on postoperative department before readmission Day of readmission to ICU (weekend)
Odds Ratio (OR)
95% Confidence Interval for OR
p Value
0,91 0,98 1,04 0,78 3,10 0,85 1,68 0,754 0,97 0,80 0,80 2,34 0,42 11,23 1,41 1,27 1,68 1,68 1,0 0,87
0,87-0,96 0,85-1,13 0,43- 2,55 0,30-2,01 1,12-8,58 0,29-2,49 0,58-4,87 0,29-1,95 0,29-3,21 0,31-2,06 0,77-5,50 0,99-5,55 0,12-1,47 0,93-135,99 0,24-8,37 0,34-4,72 0,27-10,31 0,27-10,32 0,95-1,05 0,27-2,81
0,001 0,079 0,92 0,60 0,03 0,77 0,33 0,56 0,97 0,65 0,66 0,052 0,17 0,055 0,70 0,72 0,57 0,21 0,91 0,81
0,91
0,83-0,99
0,028
0,59
0,29-1,54
0,28
Abbreviations: COPD, chronic obstructive pulmonary disease; ICU, intensive care unit; MI, myocardial infarction; PCI, percutaneous coronary intervention.
determinants of patient mortality after readmission have not been described. The authors’ multivariate logistic regression showed that older age, previous myocardial infarction, and longer initial stay in the postoperative department were independent risk factors for mortality after ICU readmission. Clinical variables including sex, hypertension, diabetes, COPD, CKD, stroke, hyperlipidemia, extracardiac arteriopathy, previous cardiac surgery, previous PCI, or EuroSCORE did not significantly increase mortality after readmission. However, it should be noted that readmitted patients were characterized by a high incidence of elevated EuroSCORE values (eg, mean EuroSCORE values 6 ⫾ 3.1). Moreover, prior studies have shown that these variables are associated strongly with higher probability for ICU readmission,1,3,6,7,9,16,20 which is associated with higher mortality, morbidity, and surgical risk. For that reason, the authors suggest that the previously listed variables increase the risk of readmission but do not increase the mortality of readmitted patients. Type of hospital admission, type of surgery, and length of stay also are well-known risk factors of mortality and morbidity of patients readmitted to the ICU.21,22 In cardiac surgery patients, the length of initial stay in the ICU is one of the strongest risk factors for readmission to the ICU.10–12 However, the influence of the urgency of the operative procedure (elective v urgent) on readmission rates differed among studies. Benetis et al16 suggested that urgent surgery is a risk factor for ICU readmission in patients with cardiac complications, while Bardell and colleagues12 refuted these findings. In the authors’ analysis, they found no evidence that length of stay or surgery status had any impact on mortality in patients who were readmitted to the ICU. Some studies also suggested that admissions to the ICU on a weekend or after “working hours” (weekdays v weekend) was associated with increased hospital mortality.23 However, the “weekend effect” as a risk factor for ICU readmission never has been evaluated in detail. The authors’ study, based on nearly 11,000 thousand patients, revealed that the day of admission to the postoperative department or the day of readmission to the ICU had no impact on mortality rates.
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IN-HOSPITAL MORTALITY WITH ICU READMISSION
The effect of length of stay in the postoperative ward on ICU readmission has not been reported in previously published studies although it may influence readmission mortality. The authors’ data revealed that mean length of stay in the postoperative cardiac surgery department was longer in patients readmitted to the ICU who subsequently died than in readmitted patients who survived the stay. CONCLUSIONS
This large, single-center study found that 1.8% of patients undergoing various types of cardiac surgery procedures were
readmitted to the ICU. Patient readmission to the ICU increased the in-hospital mortality rate 5 times compared to non-readmitted patients. The main causes of patient readmission to the ICU were cardiac and respiratory complications. The highest mortality rate of patients readmitted to the ICU was observed among patients who underwent CABG surgery. Older age, previous myocardial infarction, and long length of stay in the postoperative ward were identified as independent risk factors for patient death after readmission to the ICU.
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