Study Characteristics
This study is a retrospective control study in the model establishment and prospective study in the model validation. The second affiliated hospital of Zhejiang university school of medicine is an academic teaching hospital. The general ICU has 40 monitoring beds including 22 single rooms (55%) and treats 2000 patients every year with a full range of diseases. We applied standard infection prevention and control (IPC) strategies for MDR included active surveillance, contact precautions, hand hygiene, chlorhexidine sponge baths, environmental disinfection, antibiotic management, monitoring and feeds back by an IPC professional once a month from 01/01/201717. Collection sites of active surveillance include sputum, urine, feces, pharynx swabs and rectal swabs and collected once a week while doctors increase the culture of different sites according to the patient's condition. According to our statistics, the positive rate of active surveillance is 2.9% with increasing trend in recent years. The CRE carriage rate is 7.3–9.7% and the CRGNB carriage rate is nearly 20%17.
The general ICU database uses the similar structure of Medical Information Mart for Intensive Care (MIMIC) database to collect basic patients’ information, medical advice, image examination, laboratory testing, nursing and doctor documents18. MIMIC is an openly available dataset associated with over 60,000 patients who stayed in critical care units of the Beth Israel Deaconess Medical Center18. Our database includes demographics, vital signs, laboratory tests, medications, and more. The database is comprised of nearly 10,000 ICU patients, and the data have been updated daily.
Bacterial detection
Model Establishment
1) Participants: all the patients in the general ICU database. Patients with positive culture of CR-GNB is defined as CR-GNB carriage. Exclude standard: i) patients with the length of ICU stay less than a week; ii) patients with a positive culture of CR-GNB within 48 hours of admission; iii) patients with no screening within 48 hours of ICU admission. See Fig. 1 for the flow chart.
2) predictable outcomes: part of the cultures we retain is routine screening, and the other part retained by doctors according to clinical needs. The result is defined as positive group when the culture is CRGNB. The negative results of cultures mean negative group. Laboratory physician carry out the drug susceptibility test with the broth microdilution method by a with analysis instruments (VITEK2 AST-GN16 French). Minimum inhibitory concentration (MIC) determination and interpretation were determined was equal to the Clinical and Laboratory Standards Institute (CLSI)19. Carbapenem resistance is defined as MIC of meropenem and imipenem larger than 4 mg/lite.
3)Variable selection: demographic data, vital signs, basic and primary diseases, important test indicators, operations histories, and antibiotic use records in the prior month. We select 65 variables into our study included single room at the time of admission, drainage tubes, primary diseases, complications such as diabetes, infection indicators, invasive procedures, and vital signs that may indicate infection, as detailed in Table 1. The interval of data sampling is limited to a week before the specimens’ collection. We delete independent variables with the missing more than 50% and the other missing values are processed by multiple interpolations.
Table 1
Basic characteristics of variables
| Positive CRGNB carriage | Negative CRGNB carriage | P | OR and 95%CI |
N | 1385 | 1535 | | |
AGE | 58.27 | 58.60 | 0.63 | |
Gender (Man) | 60.20% | 62.21% | 0.000 | 0.899 (0.849–0.952) |
Weight | 68.32 | 57.97 | 0.081 | |
Single | 703 (50.76%) | 875 (55.37%) | 0.001 | 0.778 (0.672-0.900) |
Hospital residence history (< a month) | 135 (9.75%) | 256 (16.68%) | 0.000 | |
PRIMARY DISEASE | | | | |
Infectious Diseases | 163 (11.76%) | 194 (12.64%) | / | |
Trauma | 369 (26.64%) | 305 (19.87%) | / | |
Cardio-cerebrovascular accident | 247 (17.83%) | 255 (16.61%) | / | |
Postoperative diseases | 151 (10.90%) | 227 (14.79%) | / | |
Internal medicine diseases | 98 (7.08%) | 187 (12.18%) | / | |
Other | 357 (25.78%) | 364 (23.71%) | / | |
COMPLICATIONS | | | | |
Malignant tumor | 102 (7.36%) | 150 (9.77%) | 0.034 | 0.75(0.574–0.979) |
Chronic kidney disease | 71 (5.12%) | 101 (6.58%) | 0.134 | |
Diabetes Mellitus | 108 (7.80%) | 114 (7.43%) | 0.550 | |
Hematological Disease | 62 (4.48%) | 65 (4.23%) | 0.630 | |
Cardiovascular disease | 52 (3.75%) | 66 (4.30%) | 0.549 | |
Liver cirrhosis | 7 (0.51%) | 21 (1.37%) | 0.02 | 0.375(0.159–0.887) |
Chronic lung disease | 7 (0.51%) | 12 (0.78%) | 0.385 | |
CLINICAL FEATURE | | | | |
CRRT | 144 (10.39%) | 214 (13.94%) | 0.04 | 0.716(0.572–0.897) |
Mechanical ventilation | 836 (60.36%) | 1238 (80.65%) | 0.000 | 0.365(0.309–0.431) |
Tracheostomy | 127 (9.16%) | 143 (9.31%) | 0.892 | |
Invasive catheterization | 343 (24.76%) | 674 (43.90%) | 0.000 | 0.04(0.028–0.056) |
History of cephalosporins (< a month) | 450 (32.49%) | 906 (59.02%) | 0.000 | 0.334(0.287–0.389) |
History of carbapenems (< a month) | 388 (28.01%) | 524 (34.14%) | 0.000 | 0.751(0.641–0.879) |
History of glucocorticoids (< a month) | 310 (22.38%) | 400 (26.06%) | 0.021 | 0.818(0.690–0.970) |
Operation history (< six month) | 386 (27.87%) | 791 (51.53%) | 0.000 | 0.363(0.311–0.424) |
Drainage tube | 533 (38.48%) | 576 (37.52%) | 0.594 | |
Fever (temperature > 38.5℃) | 679 (49.02%) | 777 (50.61%) | 0.390 | |
High APACHE II scores (> 20 points) | 594 (42.89%) | 689 (44.89%) | 0.277 | |
APACHE II scores | 18.76 | 20.32 | 0.000 | 0.602(0.479–0.687) |
Charlson scores | 2.18 | 2.28 | 0.180 | |
Hypoleukaemia | 97 (7.00%) | 186 (12.11%) | 0.000 | 0.553(0.428–0.715) |
Thrombopenia | 176 (12.71%) | 257 (16.74%) | 0.003 | 0.734(0.596–0.903) |
Acute kidney injury | 301 (21.73%) | 424 (27.62%) | 0.001 | 0.750(0.632–0.889) |
Acute liver failure | 148 (10.69%) | 255 (16.61%) | 0.000 | 0.618(0.497–0.768) |
VITAL SIGNS | | | | |
Pulsemax | 109.11 | 115.79 | 0.000 | |
Respiratory ratemax | 24.58 | 27.03 | 0.000 | |
Temperaturemax | 38.33 | 38.47 | 0.000 | |
GCSmin | 8.38 | 10.64 | 0.000 | |
SBPmax | 166.16 | 170.75 | 0.000 | |
LABORATORY INDEXES | | | | |
WBCmax | 14.427 | 16.46 | 0.000 | |
WBCmin | 8.67 | 7.23 | 0.000 | |
NEUmax | 89.58 | 91.51 | 0.000 | |
HCTmax | 44.04 | 48.02 | 0.009 | |
CRPmax | 118.32 | 132.79 | 0.000 | |
PCTmax | 5.51 | 7.36 | 0.000 | |
PLTmin | 137.96 | 114.23 | 0.000 | |
HBmin | 78.06 | 73.66 | 0.000 | |
CRmax | 104.40 | 131.68 | 0.000 | |
CTnImax | 3.73 | 12.00 | 0.086 | |
CK-MBmax | 42.61 | 62.94 | 0.000 | |
ALTmax | 99.73 | 148.24 | 0.003 | |
ASTmax | 197.71 | 354.71 | 0.001 | |
TBILmax | 27.07 | 35.63 | 0.000 | |
DBILmax | 8.78 | 12.44 | 0.000 | |
IBILmax | 18.98 | 24.66 | 0.000 | |
TPmax | 61.96 | 65.71 | 0.000 | |
ALBmin | 28.59 | 26.58 | 0.000 | |
PTmax | 17.44 | 18.80 | 0.000 | |
APTTmax | 51.78 | 57.47 | 0.000 | |
FBGmax | 4.94 | 5.39 | 0.000 | |
D-Dimermax | 7043.89 | 8052.42 | 0.000 | |
GLUmax | 12.72 | 14.49 | 0.001 | |
LACmax | 3.41 | 4.39 | 0.000 | |
CRRT: Continuous Renal Replacement Therapy; GCS : Glasgow coma scale; SBP: Systolic pressure; WBC: White blood cell count; NEP: neutrophil percentage; HCT: Hematokrit; CRP: C-Reactive Protein; PCT: procalcitonin; PLT: Platelet count; HB: hemoglobin; CR: Creatinine; CTnI: troponin; CK-MB: Creatine kinase isoenzyme MB; ALT: Alanine transaminase; AST: Aspartate aminotransferase; TBIL: Total bilirubin; DBIL: Direct bilirubin; IBIL: Indirect bilirubin; TP: Total protein; ALB: Albumin ; PT: Prothrombin time; APTT: Activated partial thromboplastin time; FBG: Fibrinogen; GLU: Blood glucose; LAC: Lactic acid; |
The maximum and minimum values of the subscript of some parameters are the maximum or minimum values in the specified collection node, which are determined according to the clinical significance. |
4) Statistical methods: we use MySQL and Navicat to complete data collection with structured query language. Data analysis are accomplished through R and RStudio with related packets. Multivariate logistic regression and three machine learning algorithms, as decision tree, random forest, and XGBoost, are selected to establish the models. The main R packets include "glm", "rpart", "randomForest", "xgboost" and "rattle". In univariate analysis, numerical variables are tested by independent sample T-test, dichotomous variables are completed by the chi-square test, and a P value less than 0.05 is considered as statistical significance. All samples are grouped into 70% training set, 15% validation set, and 15% test set. Multivariate logistic regression uses the step-by-step decreasing method to adjust the parameters. Five hundred trees are constructed and the exhaustive method is used to adjust the parameters in the Random forest, and the importance of measurable variables is presented by the corresponding visual package. The specific and task parameters of the XGBoost linear rise are adjusted according to the performance of the model. The evaluation parameters include sensitivity, specificity, positive predictive value, negative predictive value, and area under the receiver operating characteristic (AUROC) curves.
Prospective Study
1) Study duration: 09/01/2019 to 12/31/2019.
2) Protocol: i) determination of the optimal prediction model through model evaluation; ii) application of the model for all patients once he admitted to ICU to make daily predictions. iii) termination of prediction with the following conditions: a) when prediction results suggest high risk (CR-GNB carriage will positive within a week), stop prediction and enter the weekly observation period; b) when patients leave the ICU ward, including transfer, discharge or death. iv) analysis of the CR-GNB carriage within a week compare with the predicted results and calculation of the relevant evaluation indexes and evaluation the model performance. v) all the predicted results are kept secret to clinicians, and this study does not interfere with clinical decision-making. For patients with CRGNB carriage, we move them into a single room and take standard measures of IPC. During the period of this study, there was no significant change in the incidence of nosocomial sensation.