Central vascular access is quite vital for ICU patients and about 90% of bloodstream infection is related to CVC(7). The overall incidence and incidence rate of CRBSI of this study was 1.08% and 1.27 per 1000 CVC-days, which is similar to the CRBSI rate of 1.1 per 1000 CVC-days in the United States as determined by the CDC NSHN and lower than the rate of 3.7 in Europe reported by the European Centre for Disease Prevention and Control, compared with developed countries(8). Chopdekar K., et al reported the average CRBSI incidence at 9.26 per 1000 CVC-days in ICUs in a tertiary care teaching hospital in Mumbai(9). However, the rate of Hematology ICU was approximately 3-fold higher than the overall rate. All patients in Hematology ICU had a bone marrow transplantation, who were in presence of inhibition of body immunity. They were extremely susceptible that any bacteria in the environment. The incidence of CRBSI varies in different areas, which might be related to the patient's condition, catheter selection, catheter placement sites and catheter maintenance, or the definition of diagnostic criteria for CRBSI might varies.
ICU patients are usually in complex and critical condition. Due to the needs of monitoring and treatment, a variety of invasive operations such as central venous catheters are usually required. All these factors will increase the possibility of blood stream infection in patients. Once bloodstream infection occurs, especially CRBSI, the patient's condition rapidly becomes worse, causing sepsis easily and even leading to death, which brings great challenges to medical staffs. Studies have shown that the mortality rate of ICU patients with CRBSI is higher than that of patients without CRBSI(10).
This study found 82 cases of CRBSI occurred in 6 ICUs from July 2013 to June 2018 in total, among which the incidence of CRBSI is highest in Hematology ICU (6.63% and 3.52 per 1000 catheter days, respectively), which is higher than Rabensteiner’s study(2.6 per 1000 catheter days)(11). The lowest is in VIP ICU (0.37% and 0.14 per 1000 catheter days, respectively). Patients with malignant hematologic diseases are mainly treated in the hematology ICU. They are in immunosuppressed state, and broad-spectrum antibiotics are routinely used to prevent infection. Since all patients need chemotherapy treatment, almost all of them have central venous catheters during hospitalization, which increases the risk of infection, leading to the incidence of CRBSI higher than these of other ICUs. It should be noted that although the incidence of CRBSI in hematology ICU in this study was higher than these in other ICUs, however, it was far lower than that in the study of Jing Xueming(12) and Chen Xing(13), which may be related to catheter site selection.
Mostly elderly patients are admitted in VIP ICU. Although their general conditions are not good, the high ratio of the ICU medical staff, adequate equipment security, and in-depth understanding of patients’ situation can bring individualized diagnosis and treatment to these patients. Those advantages can ensure every patient's condition stable, thus the incidence of CRBSI in VIP ICU is the lowest.
In this study, the incidence of CRBSI in cardiac ICU was the second highest, while the incidence of CRBSI per 1000 catheter days was the second lowest. The reason might be that most patients were observed in cardiac ICU for 48 hours and often transferred between cardiothoracic ICU and general wards. The high beds turnover rate leads to very low average number of days of catheterization. Thus, there is a mismatch between the incidence of CRBSI and the infection rate per 1000 catheter days.
We found the median hospital day attributable to CRBSI was 20.0 days, which was much higher than the extra length of stay (7 days) of Higuera’s and Leistner ‘s study(14, 15). Rosenthal’s study in Argentina in six ICUs among three hospitals found that the hospital day attributable to CRBSI was 11.9 days(16). Dimick found severe surgical ICU patients, the attributable hospital days to CRBSI was 20 days, which was quite similar as this study(17).
Studies at home and abroad have shown that CRBSI can prolong the length of stay in ICU and the total length of stay. However, the results of different studies vary greatly due to the differences in medical charge patterns and statistical methods such as patient grouping in different regions. If patients are simply divided into infected and uninfected groups, and then the difference in average length of stay between the two groups is compared, it will produce biased estimates due to the influence of patients' basic diseases and physical states. By means of matching, confounding factors are controlled between the case group and the control group, which can relatively reduce the differences between the underlying diseases and other factors of the patients
Multiple studies have shown that the extension of hospital stay is one of the important factors affecting the increase of nosocomial infection(18, 19). In this study, patients with CRBSI extended the hospital stay by an average of 20 days compared with patients without CRBSI. Therefore, the hospital stay of patients is positively correlated with the occurrence of nosocomial infection, and the two may be mutually causal. Patients with CRBSI need targeted treatment, increased use of antimicrobial agents and corresponding supportive treatment, so as to prolong the course of disease, thus leading to reduced ICU bed turnover rate and increased bed utilization rate. The excessively high utilization rate of hospital beds, on the one hand, leads to the delay of treatment of patients in need of treatment because there is no idle bed, and increases the potential of doctor-patient disputes(20-23).
This study is the second to report the estimated additional costs of CRBSI of ICU in China. The additional average medical costs of each case of CRBSI in the ICU were $ 67,923. The medical taverage cost attributable to CRBSI is $18,781, for which antibiotic agents mostly account, almost twice as much as the cost in the control group.
Dimick‘s study in US found the additional cost of CRBSI in surgical ICU was $11,523 to $165,735(17). David et al. found the hospital costs attributable to CRBSI in ICU in Canada was $11, 971(24). Another study on the cost of CRBSI in Canada found the cost of CRBSI acquired ICU is $12,321(25).
Since October 1st 2008, the United States has stipulated that the medical costs caused by CRBSI are paid by the hospital, and patients do not have to pay. Currently China has not established similar regulations. In China, most of the special antibiotics for the antimicrobial resistant bacteria infection treatment, such as carbapenem-resistant Enterobacteriaceae bacteria, are quite expensive and not covered by the basic medical reimbursement.
First of all, the occurrence of CRBSI will increase the cost of microorganism culture and drug sensitivity test of patients. In addition, the cost of antibiotics such as lineczolid, tigecycline and polymyxin used in the early empirical treatment and targeted treatment of pathogenic bacteria is quite expensive, which greatly increases the cost of treatment for patients. The overuse of antibiotics not only consumes excessive health resources, but also increases the risk of nosocomial infection and the emergence and spread of drug-resistant bacteria. Therefore, reducing the incidence of CRBSI can not only reduce the disease burden of patients, but also reduce the occurrence of nosocomial infection and the spread of drug-resistant bacteria, which is of great significance for improving the quality of medical care and ensuring the safety of patients.
Once the patient of ICU got a CRBSI, lots of high-level antibiotic agents would be used, which were substantially expensive and less covered by medical insurance service. This study innovatively considered the cost of antibiotics which was closely related to the incidence of CRBSI. As a proactive anticipative strategy, microscopic examination of CVC blood samples might be used to anticipate CRBSI in an earlier stage(26).
Our study has some limitations. 1) All information of patients with CVC was recorded lack of intubation position. The rates of different central lines were unavailable. 2) We can not analyze the drug used for different organism, cause several antibiotic agents could be used for treatment of certain organism, and the date of prescription was not recorded. 3) Other infections were not excluded, which need to be considered in the future research.