ORIGINAL RESEARCH article

Front. Med., 17 December 2020

Sec. Intensive Care Medicine and Anesthesiology

Volume 7 - 2020 | https://doi.org/10.3389/fmed.2020.593808

The Prevalence, Risk Factors, and Outcomes of Sepsis in Critically Ill Patients in China: A Multicenter Prospective Cohort Study

  • MW

    Meiping Wang 1,2†

  • LJ

    Li Jiang 3†

  • BZ

    Bo Zhu 2†

  • WL

    Wen Li 2

  • BD

    Bin Du 4

  • YK

    Yan Kang 5

  • LW

    Li Weng 4

  • TQ

    Tiehe Qin 6

  • XM

    Xiaochun Ma 7

  • DZ

    Duming Zhu 8

  • YW

    Yushan Wang 9

  • QZ

    Qingyuan Zhan 10

  • MD

    Meili Duan 11

  • WL

    Wenxiong Li 12

  • BS

    Bing Sun 13

  • XC

    Xiangyuan Cao 14

  • YA

    Yuhang Ai 15

  • TL

    Tong Li 16

  • XZ

    Xi Zhu 17

  • JJ

    Jianguo Jia 18

  • JZ

    Jianxin Zhou 19

  • YH

    Yan He 1*

  • XX

    Xiuming Xi 2*

  • CC

    China Critical Care Sepsis Trial (CCCST) workgroup

  • 1. Department of Epidemiology and Health Statistics, School of Public Health, Capital Medical University, Beijing, China

  • 2. Department of Critical Care Medicine, Fuxing Hospital, Capital Medical University, Beijing, China

  • 3. Department of Critical Care Medicine, Xuanwu Hospital, Capital Medical University, Beijing, China

  • 4. Medical Intensive Care Unit, Peking Union Medical College Hospital, Beijing, China

  • 5. Department of Critical Care Medicine, West China Hospital, Sichuan University, Chengdu, China

  • 6. Department of Critical Care Medicine, Guangdong Geriatric Institute, Guangdong General Hospital, Guangdong, China

  • 7. Department of Critical Care Medicine, The First Affiliated Hospital of China Medical University, Shenyang, China

  • 8. Surgical Intensive Care Unit, Department of Anaesthesiology, ZhongShan Hospital, FuDan University, Shanghai, China

  • 9. Intensive Care Unit, The First Hospital of Jilin University, Changchun, China

  • 10. Department of Critical Care Medicine, China-Japan Friendship Hospital, Beijing, China

  • 11. Department of Critical Care Medicine, Beijing Friendship Hospital, Capital Medical University, Beijing, China

  • 12. Surgical Intensive Care Unit, Beijing Chaoyang Hospital, Capital Medical University, Beijing, China

  • 13. Department of Respiratory and Critical Care Medicine, Beijing Institute of Respiratory Medicine, Beijing Chaoyang Hospital, Capital Medical University, Beijing, China

  • 14. Department of Critical Care Medicine, General Hospital of Ningxia Medical University, Ningxia, China

  • 15. Department of Critical Care Medicine, Xiangya Hospital, Central South University, Changsha, China

  • 16. Department of Critical Care Medicine, Beijing Tongren Hospital, Capital Medical University, Beijing, China

  • 17. Department of Critical Care Medicine, Peking University Third Hospital, Beijing, China

  • 18. Surgical Intensive Care Unit, Xuanwu Hospital, Capital Medical University, Beijing, China

  • 19. Department of Critical Care Medicine, Beijing Tiantan Hospital, Capital Medical University, Beijing, China

Abstract

Background: Sepsis is a main cause of morbidity and mortality in critically ill patients. The epidemiology of sepsis in high-income countries is well-known, but information on sepsis in middle- or low-income countries is still deficient, especially in China. The purpose of this study was to explore the prevalence, characteristics, risk factors, treatment, and outcomes of sepsis in critically ill patients in tertiary hospitals in China.

Methods: A multicenter prospective observational cohort study was performed with consecutively collected data from adults who stayed in any intensive care unit (ICU) for at least 24 h; data were collected from 1 January 2014 to 31 August 2015, and patients were followed until death or discharge from the hospital.

Results: A total of 4,910 patients were enrolled in the study. Of these, 2,086 (42.5%) presented with sepsis or septic shock on admission to the ICU or within the first 48 h after admission to the ICU. ICU mortality was higher in patients with sepsis (13.1%) and septic shock (39.0%) and varied according to geographical region. Acinetobacter, Pseudomonas, and Staphylococcus infections were associated with increased ICU mortality. In addition, age, Acute Physiology, and Chronic Health Evaluation II (APACHE II) scores, pre-existing cardiovascular diseases, malignant tumors, renal replacement therapy (RRT), and septic shock were independent risk factors for mortality in patients with sepsis. The prompt administration of antibiotics (OR 0.65, 95% CI 0.46–0.92) and 30 mL/kg of initial fluid resuscitation during the first 3 h (OR 0.43, 95% CI 0.30–0.63) improved the outcome in patients with septic shock.

Conclusions: Sepsis was common and was associated with a high mortality rate in critically ill patients in tertiary hospitals in China. The prompt administration of antibiotics and 30 mL/kg fluid resuscitation decreased the risk of mortality.

Introduction

Sepsis is a major challenge for public health; it is the main cause of morbidity and mortality in intensive care units (ICUs) and is associated with poor outcomes (–). In the United States, the incidence of sepsis is 535 cases per 100,000 person-years and is increasing (). A meta-analysis of data from high-income countries predicted that 31.5 million sepsis and 19.4 million severe sepsis cases will occur annually worldwide (). Recently, global data from the Intensive Care Over Nations (ICON) audit showed that 29.5% of patients had sepsis during their ICU stay, and the occurrence rates varied regionally from 13.6 to 39.3% ().

Although several studies have shown that mortality due to sepsis has declined in the past two decades due to advanced supportive care and the introduction of guidelines, the exact mortality rate is still controversial (–). In the United States, mortality due to sepsis decreased from 27.8 to 17.9% between 1979 and 2000 (). Similarly, in Australia and New Zealand, mortality decreased by almost half (from 35.0 to 18.4%) between 2000 and 2012 (). However, a multicenter study showed that the in-hospital mortality rate in patients with septic shock was 50.9% in Germany and 58.6% in Italy (, ).

To date, there have been few large epidemiological investigations of sepsis in middle- and low-income countries. The ICON audit indicated that low income was associated with increased mortality (). A multicenter point-prevalence study in Turkey showed that the prevalence of sepsis was 30.8%, with a 75.9% mortality rate in patients with septic shock (). China is a middle-income country that accounts for one-fifth of the world's population. Information on the epidemiology of sepsis has thus far been limited to particular populations (–) or obtained with a cross-sectional study (), which may not accurately reflect the epidemiology of sepsis in critically ill patients.

The aim of this prospective multicenter observational cohort study, which was conducted by the China Critical Care Sepsis Trial (CCCST) group, was to explore the prevalence, characteristics, risk factors, treatment, and outcomes of sepsis in critically ill patients in tertiary hospitals in China.

Methods

Study Design

The CCCST was a prospective multicenter observational cohort study designed to assess the prevalence, characteristics, risk factors, and short- and long-term outcomes in critically ill patients in 18 ICUs in 16 tertiary hospitals in 7 geographical regions from 1 January 2014 to 31 August 2015. Eligible patients who were admitted consecutively to ICUs were aged 18 years or older and stayed in the ICU for at least 24 h. If the patients were admitted to the ICU repeatedly during the same hospitalization event, only the first admission was considered.

Data Collection

The following variables were extracted from the CCCST dataset: baseline demographic data (age, sex, height, and weight), source and type of admission, main diagnosis, and comorbid conditions. The severity of illness was represented by the Acute Physiology and Chronic Health Evaluation II (APACHE II) score () and the Sequential Organ Failure Assessment (SOFA) score (), which were calculated based on clinical and laboratory values. The APACHE II score was calculated within 24 h of admission to the ICU. The SOFA score was recorded consecutively for 7 days after admission to the ICU, and each component of the SOFA score was evaluated at the onset of sepsis. The use of mechanical ventilation (MV), the use of vasopressors (including dopamine, epinephrine, norepinephrine, and dobutamine), the serum creatinine (SCr) level, and urine output were also continuously recorded for 7 days or until discharge. Other clinical variables, such as blood pressure, arterial partial oxygen pressure (PaO2), fraction of inspired oxygen (FiO2), nutritional therapy, and renal replacement therapy (RRT), were recorded.

The occurrence, severity, and diagnosis of sepsis were assessed consecutively for 28 days or until discharge. The sites and types of infection, biological samples, and culture results were also recorded. The interval between the first use of targeted antibiotics and the onset of sepsis or septic shock, other antibiotics administered before sepsis and retained pre-sepsis blood cultures were also recorded. The primary outcome was ICU mortality and in-hospital mortality; the lengths of ICU and hospital stays were secondary outcomes.

Definitions

According to the “Surviving Sepsis Campaign (SSC): International Guidelines for the Management of Sepsis and Septic Shock: 2016” (), sepsis was defined as life-threatening organ failure (an acute change in the SOFA score ≥2 points) caused by infection on admission to the ICU or within the first 48 h after admission to the ICU. Septic shock was defined as sepsis associated with hypotension that required the administration of vasopressors to maintain a mean arterial pressure >65 mmHg and a serum lactate level >2 mmol/L, despite adequate fluid resuscitation. Community-acquired sepsis was defined as sepsis that was present on admission or that developed within 48 h after hospital admission. Hospital-acquired sepsis was defined as sepsis that developed >48 h after hospital admission. For patients with multiple episodes of sepsis, only the first episode was recorded. Acute kidney injury (AKI) and severity were categorized according to the Kidney Disease: Improving Global Outcomes (KDIGO) guidelines (). Acute respiratory distress syndrome (ARDS) was defined as a PaO2/FIO2 ratio <300 mmHg, according to the Berlin definition (). According to the International Sepsis Forum Consensus Conference on the Definitions of Infection in the Intensive Care Unit, catheter-related sepsis was defined as at least one positive peripheral blood culture with (1) the same microorganism (the same species with the same sensitivities) isolated from the catheter segment or the periphery; (2) the same microorganism isolated from the peripheral blood; or (3) the same organism identified in paired central and peripheral blood cultures, wherein the central blood culture was positive ≥2 h earlier than the peripheral blood culture (). An unscheduled operation without sufficient preparation within 24 h of the onset of injury was defined as emergency surgery. However, elective surgery was performed after adequate preoperative preparation.

Statistical Analysis

Continuous variables are presented as the means ± standard deviations (SDs) or medians [interquartile ranges (IQRs)], and categorical variables are presented as percentages. Differences between the groups were compared with the t-test, one-way analysis of variance or Wilcoxon rank-sum test for continuous variables and the chi-squared test for categorical variables. Multivariable stepwise logistic regression analysis was used to explore the risk factors for ICU mortality in patients with sepsis or septic shock. Variables with a p < 0.2 in the univariate analysis were entered into the multivariable logistic regression analysis. In the multivariable analysis, the centers were included as a random effect. Odds ratios (ORs) with 95% confidence intervals (CIs) were calculated by logistic regression analysis. A two-sided p < 0.05 was considered statistically significant. All analyses were performed with IBM SPSS statistical software version 25.0 for Windows (IBM, Armonk, NY, USA) and R version 3.6.1 (http://www.r-project.org).

Results

Characteristics of the Participants

A total of 14,604 critically ill patients were consecutively admitted to the ICUs. A total of 4,910 patients were included in the CCCST. Of those, 2,086 (42.5%) had sepsis, including 1,134 (54.4%) with septic shock (Figure 1). Among all the participants, 3,009 (61.3%) patients had at least one episode of acute organ dysfunction. Patients with sepsis were more likely to be male (65.3 vs. 62.5%), have higher APACHE II (19.0 vs. 13.0) and SOFA (8.0 vs. 6.0) scores, have more comorbid conditions (no comorbidities, 25.1 vs. 38.5%) and organ dysfunction (no organ dysfunction, 22.2 vs. 50.9%), require more MV (77.4 vs. 64.2%) and RRT (18.3 vs. 11.6%), have a longer length of ICU stay (days, 8.0 vs. 4.0) and have higher ICU (27.2 vs. 9.5%) and in-hospital (33.0 vs. 13.1%) mortality rates than those who did not develop sepsis (Table 1). When sepsis was redefined based on the Sepsis-1 definition (see Supplementary Table 1), 200 (4.1%) non-sepsis patients met the definition. The characteristics and outcomes are shown in Supplementary Table 2.

Figure 1

Table 1

All patients (n = 4,910)Non-sepsis (n = 2,824)Sepsis (n = 2086)P-value
Age, mean ± SD61.6 ± 17.960.9 ± 18.062.5 ± 17.80.047
Sex, male (%)3,128 (63.7)1,766 (62.5)1,362 (65.3)<0.001
Severity on admission
   APACHE II, median (IQR)16.0 (10.0–22.0)13.0 (8.0–19.0)19.0 (14.0–25.0)<0.001
 SOFA, median (IQR)
      -Initial8.0 (5.0–11.0)6.0 (4.0–9.0)8.0 (5.0–11.0)<0.001
      -Mean6.0 (4.0–10.0)5.0 (3.0–8.0)7.0 (4.0–10.0)<0.001
      -Max9.0 (6.0–12.0)7.0 (4.0–10.0)9.0 (6.0–13.0)<0.001
Admission diagnosis, n (%)<0.001
   Sepsis1,407 (28.7)0 (0.0)1,407 (67.4)
   Pneumonia859 (17.5)687 (24.3)172 (8.2)
   Trauma295 (6.0)237 (8.4)58 (2.8)
   Postoperative monitoring947 (19.3)811 (28.7)136 (6.5)
   Gastrointestinal374 (7.6)283 (10.0)91 (4.4)
   Heart failure411 (8.4)322 (11.4)89 (4.3)
   Neurological320 (6.5)266 (9.4)54 (2.6)
   Others297 (6.0)218 (7.7)79 (3.8)
Comorbidities, n(%)
   Respiratory disease589 (12.0)257 (9.1)332 (15.9)<0.001
   Cardiovascular disease919 (18.7)529 (18.7)390 (18.7)0.974
   Hypertension1,741 (35.5)974 (34.5)767 (36.8)0.099
   Diabetes mellitus874 (17.8)463 (16.4)411 (19.7)0.003
   Chronic renal failure543 (11.1)258 (9.1)285 (13.7)<0.001
   Cancer499 (10.2)292 (10.3)207 (9.9)0.633
   Cirrhosis119 (2.4)81 (2.9)38 (1.8)0.018
No. of comorbidities, n (%)<0.001
   None1,611 (32.9)1,087 (38.5)524 (25.1)
   11,932 (39.2)1,031(36.5)1,932 (39.2)
   2834 (17.0)442 (15.7)392 (18.8)
   ≥3533 (10.9)264 (9.3)269 (12.9)
Treatment
   MV, n (%)3,427 (69.8)1,841 (64.2)1,586 (77.4)<0.001
   RRT, n (%)707 (14.4)332 (11.6)375 (18.3)<0.001
   Vasopressor, (%)2,770 (56.4)1,165 (41.3)1,605 (76.9)<0.001
No. of organ failures, n (%)<0.001
   01,901 (38.7)1,438 (50.9)463 (22.2)
   11,357 (27.6)874 (30.9)483 (23.2)
   21,118 (22.8)465 (16.5)653 (31.3)
   ≥3534 (10.9)47 (1.7)487 (23.3)
Length of stay, days, median (IQR)
   ICU6.0 (3.0–12.0)4.0 (2.0–9.0)8.0 (4.0–16.0)<0.001
   Hospital17.0 (10.0–27.0)17.0 (10.0–25.0)18.0 (10.0–29.0)0.002
Mortality, n(%)
   ICU834 (17.0)267 (9.5)567 (27.2)<0.001
   Hospital1,058 (21.5)370 (13.1)688 (33.0)<0.001

Baseline characteristics of all the subjects.

SD, standard deviation; APACHE II, Acute Physiology and Chronic Health Evaluation; SOFA, Sequential Organ Failure Assessment; IQR, interquartile range; ICU, intensive care unit; MV, mechanical ventilation; RRT, renal replacement therapy.

Distribution of Sites and Isolated Organisms

The most common site of infection in patients with sepsis was the lungs (55.5%), followed by the abdomen (24.4%). Microorganism culture was performed in 1,843 (88.4%) patients, and 1,275 (61.1%) had one or more positive cultures (Table 2). Among the patients with positive isolates, 407 (31.9%) were infected by gram-positive organisms, and 949 (74.4%) were infected by gram-negative organisms. Acinetobacter (29.0%) was the most common gram-negative organism and was usually isolated from the lungs (37.3%), pleura (42.9%), bloodstream (29.7%), catheter-related locations (42.9%), and central nervous system (CNS) (50.0%). Staphylococcus (18.2%) was the most common gram-positive organism and was usually isolated from patients with wound/soft tissue infections (26.8%) (Table 2, Supplementary Table 3). Patients with hospital-acquired sepsis were more likely to have positive cultures of Acinetobacter (34.2 vs. 25.2%) and Pseudomonas (25.1 vs. 19.8). In the patients with septic shock, Pseudomonas (24.1 vs. 19.3%) and Candida (21.8 vs. 19.3%) isolates were likely to be present; Klebsiella isolates were less common than Pseudomonas and Candida (8.9 vs. 15.1%) isolates (Table 2). The microorganism species were significantly different according to region (see Supplementary Table 4).

Table 2

nOrigin of infection, n(%)Severity of sepsis, n(%)
Community-acquiredHospital-acquiredpSepsisSeptic shockP-value
Patients with sepsis2,0861,181 (56.6)905 (43.4)952 (45.6)1,134 (54.4)
Site of infection#
   Lung1,157 (55.5)599 (50.7)588 (61.7)0.001521 (54.7)636 (56.1)0.534
   Pleura121 (5.8)87 (7.4)34 (3.8)<0.00175 (7.9)46 (4.1)<0.001
   Abdomen510 (24.4)370 (31.3)140 (15.5)<0.001252 (26.5)258 (22.8)0.049
   Urinary tract88 (4.2)65 (5.5)23 (2.5)0.00149 (5.1)39 (3.4)0.053
   Bloodstream157 (7.5)73 (6.2)84 (9.3)0.00869 (7.2)88 (7.8)0.659
   Catheter-related sites42 (2.0)5 (0.4)37 (4.1)<0.00131 (3.3)11 (1.0)<0.001
   Wound/soft tissue107 (5.1)56 (4.7)51 (5.6)0.35979 (8.3)28 (2.5)<0.001
   CNS34 (1.6)28 (2.4)6 (0.7)0.00221 (2.2)13 (1.1)0.057
   Unknown314 (15.1)152 (12.9)162 (17.9)0.001115 (12.1)199 (19.5)0.001
Results of culture0.007<0.001
   Undetermined243 (11.6)153 (13.0)90 (9.9)179 (18.8)64 (5.6)
   Negative568 (27.2)294 (24.9)274 (30.3)238 (25.0)330 (29.1)
   Positive1,275 (61.1)734 (62.2)541 (59.8)535 (56.2)740 (65.3)
Isolated organisms&1,275
   Gram-positive407 (31.9)243 (33.1)164 (30.3)0.391165 (30.8)242 (32.7)0.482
      Staphylococcus232 (18.2)138 (18.8)94 (17.4)0.51486 (16.1)146 (19.7)0.095
      Enterococcus132 (10.4)85 (11.6)47 (8.7)0.09452 (9.7)80 (10.8)0.528
   Gram-negative949 (74.4)552 (75.2)397 (73.4)0.461412 (77.0)537 (72.6)0.073
      Acinetobacter370 (29.0)185 (25.2)185 (34.2)<0.001156 (29.2)214 (28.9)0.926
      Escherichia256 (20.1)153 (20.8)103 (19.0)0.426105 (19.6)151 (20.4)0.732
      Klebsiella147 (11.5)83 (11.3)64 (11.8)0.77381 (15.1)66 (8.9)0.001
      Pseudomonas281 (22.0)145 (19.8)136 (25.1)0.022103 (19.3)178 (24.1)0.041
   Fungi§326 (25.6)189 (25.7)137 (25.3)0.863125 (23.3)201 (27.2)0.125
      Candida249 (19.5)146 (19.9)103 (19.0)0.70488 (16.4)161 (21.8)0.018
      Aspergillus25 (2.7)18 (2.5)17 (3.1)0.45613 (2.4)22 (3.0)0.558

Distribution of the most common sites of infection and isolated organism.

#

percentage is not equal to 100 because patients may have one or more sites of infection;

&

patients may have had more than one organism isolated; CNS, central nervous system;

§

Candida, yeasts, Aspergillus, and Pneumocystis carinii were included.

Organ Dysfunction and Elements of Sepsis

Among all patients with sepsis, approximately three-fourths (74.4%) had been given antibiotics before the onset of sepsis, and 63.2% retained bacteria in their blood culture. Patients with hospital-acquired sepsis were more likely to have higher sub-SOFA scores in any organ (except the kidneys and CNS) and more likely to have AKI (45.1 vs. 39.1%) but less likely to have ARDS (37.3 vs. 49.4%) than those with community-acquired sepsis. The patients with hospital-acquired sepsis commonly received more antibiotics pre-ICU (79.8 vs. 70.4%), antibiotics within 1 h after the recognition of sepsis (76.5 vs. 53.6%) and enteral nutritional therapy (61.8 vs. 52.3%) (Table 3).

Table 3

All (n = 2,086)Community-acquired (n = 1,181)Hospital-acquired (n = 905)P-value
SOFA sub-scores, median (IQR)
   SOFA-respiratory3 (2–3)3 (2–3)3 (2–4)<0.001
   SOFA-cardiovascular2 (0–4)2 (1–4)2 (2–4)0.012
   SOFA-coagulation0 (0–2)0 (0–2)0 (0–1)<0.001
   SOFA-hepatic0 (0–2)0 (0–0)1 (0–2)0.048
   SOFA-renal0 (0–2)0 (0–2)0 (0–2)0.949
   SOFA-CNS1 (0–3)1 (0–3)1 (0–2)0.805
Organ dysfunction, n(%)
   ARDS924 (44.3)583 (49.4)341 (37.7)<0.001
   AKI870 (41.7)462 (39.1)408 (45.1)0.006
Blood culture pre-antibiotics, n (%)1,318 (63.2)718 (60.8)600 (66.3)0.004
Administration of antibiotics pre-ICU, n (%)1,553 (74.4)831 (70.4)722 (79.8)<0.001
Administration of antibiotics within 1 h of sepsis or septic shock onset, n (%)1,328 (63.7)636 (53.6)692 (76.5)<0.001
Nutritional therapy, n (%)0.006
   None225 (10.8)147 (12.4)78 (8.6)
   Pre-ICU257 (12.3)131 (11.1)126 (13.9)
   Post-ICU1,604 (76.9)903 (76.5)701 (77.5)
Nutrition prescription during ICU, n (%)<0.001
   Enteral907 (56.5)474 (52.3)433 (61.8)
   Parenteral488 (30.4)313 (34.7)175 (25.0)
   Enteral + Parenteral209 (13.1)116 (12.8)93 (13.3)

Organ dysfunction scores, use of antibiotics, and use of nutritional therapy in patients with sepsis.

SOFA, Sequential Organ Failure Assessment; res, respiratory; CNS, central nervous system; IQR, interquartile range; ARDS, acute respiratory distress syndrome; AKI, acute kidney injury; ICU, intensive care unit.

Among the patients with septic shock, the non-survivors were older, received more MV and RRT, had a longer length of hospital stay, and were more likely to have ARDS and AKI than the survivors (see Supplementary Table 5). During the first 3 h after admission to the ICU or the onset of septic shock, the survivors seemed more likely to fulfill the resuscitation goal of 30 ml/kg fluid bolus than non-survivors (43.6 vs. 32.4%), although there were no significant differences in intravenous fluid administration between the groups (24.2 vs. 21.1 ml/kg). The survivors were also commonly given antibiotics within 1 h (55.9 vs. 49.3%) of onset (Table 4).

Table 4

Survivors (n = 692)Non-survivors (n = 442)P-value
Intravenous fluid administration, ml/kg
   - 3 h, median (IQR)24.2 (11.1–30.6)21.1 (14.1–30.5)0.741
   - 6 h, median (IQR)33.8 (16.4–46.5)35.9 (21.7–50.7)0.004
   - 24 h, median (IQR)56.7 (38.2–81.5)63.4 (44.1–95.5)<0.001
30 ml/kg initial resuscitation, n(%)
   During first 3 h302 (43.6)143 (32.4)<0.001
   During first 6 h213 (30.8)126 (28.5)0.238
Vasopressor administration, n(%)
   During first 3 h360 (52.0)254 (57.5)0.073
   During first 6 h394 (56.9)281 (63.6)0.026
   During first 24 h457 (66.0)315 (71.3)0.066
   Antibiotics within 1 h, n (%)387 (55.9)218 (49.3)0.030
   Blood culture pre-antibiotics,501 (72.4)321 (72.6)0.753
n (%)

Early management of patients with septic shock.

IQR, interquartile range.

Outcomes

The ICU mortality rates were 27.2% in patients with sepsis and 9.5% in those without sepsis; the in-hospital mortality rates were 33.0 vs. 13.1%, respectively (Table 1). The ICU and in-hospital mortality varied by region (see Supplementary Table 6). In those patients without sepsis, the ICU mortality ranged from 0.8% (Central China) to 13.9% (North China), while in patients with septic shock, the ICU mortality ranged from 20.0% (East China) to 50.0% (Southwest China). There was also a gradual increase in ICU and in-hospital mortality with increasing severity of sepsis (Table 5). Although the patients with septic shock had a decreased length of hospital stay, they did have a significantly increased in-hospital mortality (Table 5). In addition, there was a direct relationship between the number of dysfunctional organs and ICU mortality (Figure 2, Supplementary Figure 1).

Table 5

CategorynSeverity illness scoresLength of stay, daysMortality, n(%)
APACHE IISOFAICUHospitalICUHospital
Onset of sepsis
   On admission to the ICU1,40720.0 (15.0–26.0)8.0 (5.0–−12.0)9.0 (4.0–−17.0)18.0 (10.0–28.0)32.2 (29.8–34.6)39.0 (36.5–41.6)
   Within 48 h67918.0 (13.0–24.0)8.0 (5.0–11.0)7.0 (4.0–13.0)8.0 (10.0–29.0)16.8 (13.8–19.6)20.5 (17.4–23.5)
Severity of sepsis
   Sepsis without shock95217.0 (12.0–22.0)6.0 (4.0–9.0)9.0 (4.0–15.0)19.0 (11.0–29.0)13.1 (11.0–15.3)19.3 (16.8–21.8)
   Septic shock1,13422.0 (16.0–28.0)9.0 (6.0–13.0)9.0 (4.0–17.0)17.0 (9.0–28.0)39.0 (36.1–41.8)44.4 (41.6–47.3)
Original of sepsis
   Community–acquired sepsis1,18519.0 (14.0–25.0)8.0 (5.0–12.0)7.0 (4.0 −15.0)16.0 (9.0–27.0)26.2 (23.7–28.7)32.0 (29.3–34.7)
   Hospital–acquired sepsis90519.0 (14.0–25.0)8.0 (5.0–11.0)9.0 (4.0 −17.0)21.0 (12.0–30.0)28.5 (25.6–31.5)34.3 (31.2–37.4)

Severity on admission to the ICU, length of stay and mortality in patients with sepsis.

APACHE II, Acute Physiology and Chronic Health Evaluation; SOFA, Sequential Organ Failure Assessment; IQR, interquartile range.

Figure 2

Factors Associated With Mortality in All Patients With Sepsis

According to the univariate analysis, lung infection was associated with high ICU mortality, and wound/soft tissue infection was associated with low mortality. However, patients with unknown sites of infection did not have elevated mortality rates. Gram-positive (especially Staphylococcus) and gram-negative (Acinetobacter and Pseudomonas) organisms were associated with elevated mortality in patients with positive cultures, whereas Escherichia did not increase ICU mortality (Table 6).

Table 6

CategoryMortality, % (95% CI)Unadjusted ORs (95% CI)
ICUHospital
Site of infection#
   Lung34.7 (31.9–37.4)40.8 (38.0–43.6)2.44 (1.98–2.99)
   Pleura29.8 (21.5–38.0)36.4 (27.7–45.1)1.14 (0.77–1.71)
   Abdomen22.9 (19.3–26.6)29.6 (25.6–33.6)0.75 (0.59–1.19)
   Urinary tract28.4 (18.8–38.0)34.1 (24.0–44.2)1.07 (0.66–1.71)
   Bloodstream31.8 (24.5–39.2)36.3 (28.7–43.9)1.28 (0.90–1.81)
   Catheter–related19.0 (6.7–31.4)21.4 (8.5–34.4)0.63 (0.29–1.36)
   Wound/soft tissue11.2 (5.14–17.3)15.0 (8.1–21.8)0.32 (0.18–0.60)
   CNS23.5 (8.5–38.6)26.5 (10.9–42.1)0.82 (0.37–1.83)
   Unknown14.6 (10.7–18.6)18.2 (13.9–22.4)0.41 (0.30–0.57)
Isolated organisms&
   Gram–positive45.7 (40.8–50.7)51.6 (46.6–56.5)2.18 (1.70–2.78)
      Staphylococcus56.0 (49.6–62.5)61.6 (55.3–67.9)3.18 (2.38–4.27)
      Enterococcus40.2 (31.7–48.6)46.2 (37.6–54.8)1.37 (0.95–1.99)
   Gram–negative35.1 (32.1–38.1)41.5 (38.4–44.7)1.31 (1.00–1.73)
      Acinetobacter44.9 (39.8–50.0)51.4 (46.2–56.5)1.99 (1.56–2.65)
      Escherichia24.6 (19.3–29.9)29.3 (23.7–34.9)0.59 (0.43–0.80)
      Klebsiella29.9 (22.4–37.4)36.1 (28.2–43.9)0.83 (0.57–1.20)
      Pseudomonas49.5 (43.6–55.4)54.8 (49.0–60.7)2.39 (1.82–3.13)
   Fungi§30.7 (25.6–35.7)38.3 (33.0–43.7)0.84 (0.64–1.10)
      Candida33.3 (27.4–39.2)42.2 (36.0–48.3)0.99 (0.74–1.32)
      Aspergillus25.7 (10.5–41.0)28.6 (12.8–44.3)0.68 (0.21–1.46)

Associations of sites of infection and isolated organisms with ICU mortality in patients with positive cultures.

#

percentage is not equal to 100 because patients may have one or more sites of infection;

&

patients may have had more than one organism isolated; CNS, central nervous system;

§

Candida, yeasts, Aspergillus and Pneumocystis carinii were included.

After adjusting for potential confounders, having no comorbid conditions and the use of antibiotics within 1 h of sepsis onset were associated with relatively lower ICU mortality in patients with sepsis. However, advanced age; high APACHE II score; comorbid cardiovascular diseases and tumors; infection with Acinetobacter, Pseudomonas, and Staphylococcus; and the use of RRT were independent risk factors for ICU mortality in patients with sepsis. Patients with septic shock had a nearly 3-fold increased risk of mortality than those without shock (OR 2.92, 95% CI 2.04–4.17, Table 7). Similarly, the Kaplan-Meier survival curves showed a decreased probability of survival in patients with septic shock than in those without shock (see Supplementary Figure 2). Achieving the resuscitation goal of 30 ml/kg during the first 3 h (OR 0.43, 95% CI, 0.30–0.63) and administering antibiotics within 1 h (OR 0.65, 95% CI, 0.46–0.92) of the onset of septic shock decreased the odds ratio for mortality in patients with septic shock (Table 7).

Table 7

CharacteristicsOR (95% CI)P-value
All patients with sepsis (n=2,086)∮
Age, for per 1 year old1.04 (1.03–1.05)<0.001
APACHE II, for per one point increase1.16 (1.13–1.21)<0.001
Comorbid condition
   None0.40 (0.24–0.64)<0.001
   Cardiovascular disease2.15 (1.45–3.20)<0.001
   Tumor2.43 (1.39–4.23)0.002
Septic shock2.68 (1.84–3.92)<0.001
Isolated microorganisms
   Acinetobacter2.21 (1.51–3.25)<0.001
   Pseudomonas2.09 (1.36–3.23)0.001
   Staphylococcus2.31 (1.08–3.25)<0.001
Renal replacement therapy2.49 (1.72–3.61)<0.001
Uses of antibiotics within 1 h0.58 (0.42–0.81)0.001
Patients with septic shock (n=1,134)£
Age, for per 1 year old1.04 (1.03–1.06)<0.001
APACHE II, for per one point increase1.17 (1.13–1.20)<0.001
Isolated microorganisms
   Pseudomonas2.14 (1.32–3.47)0.002
   Staphylococcus2.36 (1.96–4.77)0.001
Renal replacement therapy3.14 (2.09–4.73)<0.001
Use of antibiotics within 1 h0.65 (0.46 −0.92)0.001
30 mL/kg initial resuscitation during first 3 h0.43 (0.30–0.63)<0.001

Multivariate logistic regression analysis of ICU mortality in patients with sepsis or septic shock.

APACHE II, Acute Physiology and Chronic Health Evaluation; RRT, renal replacement therapy; CI, confidence interval;

∮

adjusted for age; sex; APACHE II score; SOFA-initial score; comorbid conditions; use of MV, RRT and vasopressors; sites of infection; isolated organisms; use of antibiotics within 1 h; use of antibiotics pre-sepsis; and septic shock.

£

Adjusted for age; APACHE II score; SOFA-initial score; comorbid cardiovascular diseases, hypertension, diabetes mellitus and chronic renal failure; use of MV, RRT and vasopressors; administration of antibiotics within 1 h; and 30 mL/kg fluid resuscitation within the first 3 h of onset of septic shock or sepsis-induced hypoperfusion.

Discussion

This large-scale multicenter prospective cohort study showed a high prevalence of sepsis in Chinese ICUs in tertiary hospitals. More than two-fifths of the patients developed sepsis on admission to the ICU or within 48 h after their ICU admission, more than half was septic shock. And the in-hospital mortality in those patients with septic shock was as high as 44.4%. Furthermore, Acinetobacter and Pseudomonas were the most common isolated microorganisms, and the prompt administration of antibiotics and sufficient fluid resuscitation improved survival.

The prevalence of sepsis in Chinese ICUs was similar to that in another cross-sectional study in China () and higher than that in other previous studies (, , , ). Several reasons may explain the differences. First, we excluded those who stayed in the ICU for <24 h. Second, different definitions of sepsis and organ dysfunction might be associated with difference prevalence. Moreover, the type of ICU may affect the prevalence.

In our cohort study, the overall ICU and in-hospital mortality rates were 17.0 and 21.5%, respectively. The patients with sepsis had an elevated mortality rate: more than one-quarter of the patients with sepsis (27.2%) died in the ICU, and one-third of the patients with sepsis (33.0%) died during hospitalization. In patients with septic shock, the mortality rates increased to 39.0% in the ICU and 44.4% in the hospital. These results were similar to those reported by the ICON audit (), the Sepsis Occurrence in Acutely Ill Patients (SOAP) study () and a study in Norway () but higher than those reported in other studies (, ). These discrepancies may be associated with multiple organ complications, geographical regions and the national income level. Several previous studies have reported that the mortality ranged from 7.0 to 15.0% in sepsis patients with one organ failure, while the mortality reached 45.0–88.6% in patients with four or more organ failures (, , ). Our study showed that the ICU mortality rate was 9.9% in sepsis patients with one organ failure, while it was 60.8% in those with four or more organ failures. Another finding in our study was that the mortality varied considerable among different geographical regions, which was similar to the result reported by Xie et al. (). Patients in Southwest China had a relatively high mortality rate, which may be related to the relatively underdeveloped economy. Previous studies have found that a low gross national income was associated with a higher mortality rate (), especially in low-income countries (, ). However, we did not find significantly different outcomes when sepsis was defined using the Sepsis-1 and Sepsis-3 definitions.

As in other studies, the most common site of infection was the lungs in patients with sepsis (, , , ). The frequency of abdominal infection was higher than that reported in previous studies (, , ). Nevertheless, several national studies reported similar rates of abdominal infection, ranging from 21.3 to 26.0% (24.4% in our study) (, , , ). Hospital-acquired sepsis was more likely to be associated with lung infections and less likely to be associated with abdominal infections than community-acquired sepsis. Recent studies showed that patients with hospital-acquired sepsis had an elevated mortality (–). However, we did not find that hospital-acquired sepsis was associated with significantly increased mortality, which may be related to our failure to include ICU-acquired sepsis.

In our study, organisms were isolated from 61.6% of the patients with sepsis; previous epidemiological studies reported both lower () and higher (, , 40) rates of positive isolates than that in our study. Over 70% of the patients were infected by gram-negative organisms, while one-third of the patients were infected by gram-positive organisms. Interestingly, Acinetobacter was isolated from 29.0% of the sepsis patients, which was higher than the proportions reported in previous studies (, , ), possibly because of different control strategies, the use of broad-spectrum antibiotics and the multidrug resistance of Acinetobacter species, especially the high level of resistance to carbapenems. The attention paid to sanitary precautions and the quality of care have improved substantially, but nosocomial infections still occur. In addition, there were significant regional differences in the organisms isolated from the cultures, and the reasons for the variations in the distributions of microorganisms in our study are unknown; these results are probably associated with cultivation techniques and methods.

The SSC 2016 and other studies have recommended the early optimization of antibiotic therapy, and early sufficient fluid resuscitation can improve the outcomes of patients with sepsis or septic shock (, 41, 42). Our results show that initial antibiotic administration within 1 h of the onset of sepsis decreased ICU mortality by 42% in patients with sepsis (OR 0.58, 95% CI: 0.42–0.81), and early effective fluid resuscitation decreased ICU mortality by more than half in septic shock patients (OR 0.43, 95% CI: 0.30–0.63). However, we were unable to assess the effects of the dose of antimicrobial pharmacokinetics on outcomes in those patients, which is another important factor affecting the outcomes (, 43, 44). In addition, RRT and pre-existing cardiovascular disease and malignant tumors were also associated with mortality.

This was the first cohort study to investigate the epidemiology of sepsis in critically ill patients in tertiary hospitals in China. The sample size included in the study was very large, which was an obvious strength. Nevertheless, there were still several limitations of this study. First, we excluded patients who stayed in the ICU for <24 h and those who stopped treatment within 48 h of admission to the ICU, which may have resulted in the underestimation of the prevalence and outcomes of sepsis. Second, we recorded only the first episode of sepsis for each patient because the number of patients who had two or more episodes during their ICU stay could not be estimated. Third, some of the data that were collected at the bedside (such as Glasgow coma scale score, urine output and hourly fluid balance) may not have been entered into the medical records. Fourth, the inclusion of two centers with small sample sizes (59 eligible participants) may have affected the results, although we adjusted for center in the statistical analysis. Fifth, the data of feeding strategy were not collected and we could not investigate the association between the feeding approach and outcomes (). In addition, due to traditional beliefs, some critically ill patients terminated therapy and returned home before improvement or death, which may have led to the underestimation of ICU or in-hospital mortality. However, the proportion of the patients who did so is unknown. Despite several limitations of our research, we report the prevalence, etiology, and prognosis of sepsis and the associated risk factors in critically ill adults in tertiary hospitals in China, providing a basis for further epidemiological and health burden studies of sepsis in China.

In conclusion, sepsis is common in critically ill patients in tertiary hospitals in China and is associated with increased mortality. Acinetobacter, Pseudomonas, and Staphylococcus infections were independent risk factors for ICU mortality. The initial administration of antibiotics within 1 h of sepsis onset and adequate fluid resuscitation decreased the risk of mortality. To reduce the burden of sepsis, national policies are urgently needed. Health-care-associated infection prevention programmes, early detection strategies, and appropriate antibiotic and fluid management strategies for the treatment of sepsis are critical.

Statements

Data availability statement

The datasets generated and/or analysed during the current study are available from the corresponding author on reasonable request.

Ethics statement

The study protocol was approved by the ethics committees of Fuxing Hospital, Capital Medical University (approval notice number 2013FXHEC-KY018), and all other centers. Written informed consent for participation was not required for this observational survey. The patient records and information were anonymized before analysis.

Author contributions

XX conceived of, designed, and supervised the study. MW, WenL, YK, LW, TQ, XM, DZ, YW, QZ, MD, WenxL, BS, XC, YA, TL, XZ, JJ, JZ, and the CCCST workgroup participated in the data collection. MW, LJ, BZ, and YH finalized the analysis, designed the study, and interpreted the findings. MW and LJ wrote the drafts of the manuscript. BZ, BD, and LW interpreted the findings and commented on and helped revise the drafts of the manuscript. All authors read and approved the final manuscript. All authors contributed to the article and approved the submitted version.

Funding

This work was supported by the National Science and Technology Supporting Plan of the Ministry of Science and Technology of the People's Republic of China (2012BAI11B05). The funding source had no role in the writing of the manuscript or the decision to submit it for publication.

Acknowledgments

We gratefully acknowledge the National Science and Technology Supporting Plan of the Ministry of Science and Technology of the People's Republic of China, a government fund used to improve health-care quality and data collection, for its financial support. We also acknowledge all the following members of the CCCST workgroup who contributed data and samples and have made this work possible: Qi Jiang, Zhen Zhao, Hui Song, Ling Ma, Chunyang Li, Linlin Cao, Peng Wang, Department of Critical Care Medicine, Fuxing Hospital, Capital Medical University, Beijing, China; Ying Wen, Department of Critical Care Medicine, Fuxing Hospital, Capital Medical University, Beitaipingzhuang Community Health Service Center, Haidian District, Beijing, China; Yibing Zhu, Department of Statistics, Fuwai Hospital, National Center for Cardiovascular Diseases, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China; Shouhong Wang, Department of Critical Care Medicine, Guangdong Geriatric Institute, Guangdong General Hospital, Guangdong, China; Xuelian Liao, Department of Critical Care Medicine, West China Hospital, Sichuan University, Sichuan, China; Liang Wang and Xin Li, Department of Critical Care Medicine, The First Affiliated Hospital of China Medical University, Shenyang, China; Xiaoxia Peng, Centre for Clinical Epidemiology and Evidence-based Medicine, Beijing Children's Hospital, Capital Medical University, National Centre for Children Health, Beijing, China; Yuan Xu, Department of Critical Care Medicine, Beijing Tsinghua Changgung Hospital, Beijing, China.

Conflict of interest

The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.

Supplementary material

The Supplementary Material for this article can be found online at: https://www.frontiersin.org/articles/10.3389/fmed.2020.593808/full#supplementary-material

    Abbreviations

  • ICU

    intensive care unit

  • APACHE II

    Acute Physiology and Chronic Health Evaluation II

  • RRT

    renal replacement therapy

  • OR

    odds ratio

  • ICON

    Intensive Care Over Nations

  • SOFA

    Sequential Organ Failure Assessment

  • MV

    mechanical ventilation

  • SCr

    serum creatinine

  • PaO2

    arterial partial oxygen pressure

  • FiO2

    fraction of inspired oxygen

  • SSC

    Surviving Sepsis Campaign

  • AKI

    acute kidney injury

  • ARDS

    acute respiratory distress syndrome

  • SD

    standard deviation

  • IQR

    interquartile range

  • CI

    confidence interval

  • SOAP

    Sepsis Occurrence in Acutely Ill Patients

  • ICD

    International Classification of Diseases

  • CRF

    case report form

  • GCS

    Glasgow coma scale.

References

Summary

Keywords

sepsis, septic shock, mortality, prevalance, risk factor

Citation

Wang M, Jiang L, Zhu B, Li W, Du B, Kang Y, Weng L, Qin T, Ma X, Zhu D, Wang Y, Zhan Q, Duan M, Li W, Sun B, Cao X, Ai Y, Li T, Zhu X, Jia J, Zhou J, He Y, Xi X and China Critical Care Sepsis Trial (CCCST) workgroup (2020) The Prevalence, Risk Factors, and Outcomes of Sepsis in Critically Ill Patients in China: A Multicenter Prospective Cohort Study. Front. Med. 7:593808. doi: 10.3389/fmed.2020.593808

Received

11 August 2020

Accepted

16 November 2020

Published

17 December 2020

Volume

7 - 2020

Edited by

Marcelo Arruda Nakazone, Faculty of Medicine of São José do Rio Preto, Brazil

Reviewed by

Massimo Girardis, University Hospital of Modena, Italy; Chun-Ta Huang, National Taiwan University Hospital, Taiwan

Updates

Copyright

*Correspondence: Yan He Xiuming Xi

This article was submitted to Intensive Care Medicine and Anesthesiology, a section of the journal Frontiers in Medicine

†These authors have contributed equally to this work

Disclaimer

All claims expressed in this article are solely those of the authors and do not necessarily represent those of their affiliated organizations, or those of the publisher, the editors and the reviewers. Any product that may be evaluated in this article or claim that may be made by its manufacturer is not guaranteed or endorsed by the publisher.

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