Introduction
The urinary catheter (UC) was first used in 1927 to control postoperative bleeding after prostatectomy. After the drainage design of the UC was changed from an open flask to a (sterile) closed system for collecting urine, the risk of urinary tract infection (UTI) was significantly reduced from 97% to 8% to 15% (Feneley et al., 2015). Today, UCs using closed drainage system designs are widely used with patients. Approximately 15%-25% of hospitalized patients receive short-term, indwelling UCs (Andrade & Fernandes, 2016; Chenoweth, 2014; Clarke et al., 2020; U.S. Centers for Disease Control and Prevention, 2020). Furthermore, UCs are currently used at a frequency between 35% and 79% of patient-days in acute care hospitals (Y.-Y. Chen et al., 2012; Dudeck et al., 2013).
At least eight professional societies around the world have developed guidelines for the prevention of catheter-associated UTIs (CAUTIs; Conway & Larson, 2012). In all of these guidelines, performing catheter insertion using an aseptic technique and maintaining a closed, sterile drainage system are strongly recommended. However, the quality of the evidence supporting the net clinical benefit of these guidelines is low (Category IB; Gould et al., 2019). In some studies, breaks in the closed urinary drainage system have not been shown to result in immediate harm (Bradley et al., 2018). Furthermore, the standard recommendation not to replace the drainage bag at routine, fixed intervals is poorly supported in terms of the tradeoff between clinical benefits and harm (Category II; Gould et al., 2019). Nevertheless, the weak recommendations cited in the early literature did not explore the frequency of replacing the urine drainage bag. In addition, other related guidelines do not address the need to replace the urine drainage system in the event the sterile closed system is compromised, with related recommendations mainly dependent on the opinions and practical experience of clinical experts (Conway & Larson, 2012). Therefore, it has been pointed out that some guidelines require further research, including randomized controlled trials for the replacement frequency of catheters and urine drainage systems (Pratt et al., 2007).
In the absence of symptoms of infection, most hospitals in Taiwan replace the urinary drainage system every 14 days, although this practice is not supported by research evidence. As catheter materials have continuously improved in recent years, the efficacy of replacing urinary drainage systems after longer periods (i.e., > 14 days) should be evaluated. Therefore, the hypothesis in this study was that the incidence of CAUTIs would not significantly differ between 14-day and >= 15-day urinary drainage system replacement schedules. The purpose of this study was to test the hypothesis to provide a clinical reference for an evidence-based catheter replacement schedule.
Methods
Patients and Allocation
This prospective, nonrandomized controlled study was conducted at adult wards in the infectious disease division of a 3,000-bed major teaching hospital in Taiwan. All of the patients admitted to these wards were potentially eligible, and data collection took place from July 2013 to August 2014. The most common reasons for ward admission were respiratory infections and sepsis. Patients who required an indwelling UC were eligible for the study, whereas those who did not have an indwelling UC or who stayed for fewer than 2 days in the ward were excluded. The procedures were approved (Taipei Veterans General Hospital, approval number: 2013-02-022 BC) by the institutional review board, and a written description of the study protocol was provided to the patients. The principal investigator informed the patients and their family members regarding the study purpose, and written informed consent was obtained from all the participants.
The sample size of this study was calculated based on a previous study (Keerasuntonpong et al., 2003), with an assumed two-sided alpha of .05, 80% statistical power, and 10% effect size. A pilot study was first conducted in the wards. The estimated total sample size required was estimated at a minimum of 284 participants. The enrolled participants were divided according to their preferences into the control group, which regularly replaced the urinary drainage system every 2 weeks, and the intervention group, which did not replace the urinary drainage system until UC removal (i.e., >= 15 days), to assess the impact of replacement time on the incidence of CAUTIs.
Of the 562 eligible patients, 347 were enrolled as participants (see Figure 1) and, on the basis of individual preferences, assigned either to the control group (166 patients) or to the intervention group (175 patients).
Intervention
The physicians and nurses of the wards were informed of the research study and coordination, and a label was posted on each medical record to remind staff of the research purpose and the timing for collecting samples. The medical staff did not know which group the patients were assigned to until the 14th day. In addition to providing nursing guidance, a cautionary reminder was also placed on the outside of each drainage bag, including the need to keep urine flow unobstructed and to keep the drainage bag below the level of the bladder. The investigator provided standard indwelling catheter care information to the patients and their primary caregivers, collected data on all of the indwelling UC patients, and assessed the cleanliness of the urinary bag and looked for signs of infection. The host data and UC-associated risk factors were recorded (see Table 1).
The risk factors associated with the urinary drainage system included (a) the frequency of juncture disconnections between the urinary drainage system and the catheter and (b) internal cleanliness. Cleanliness was assessed by observing the urine visually in a urinary drainage bag under a bright light and inspecting for the presence of impurities, sediment, turbidity, and blood clots.
Care Procedures of Indwelling Urinary Catheters
The department of infection control had established control strategies for preventing and monitoring CAUTIs (Y.-Y. Chen et al., 2013). Inserting/removing UCs was done at the discretion of the physician. UCs were not replaced regularly in the absence of urinary leakage, turbidity, retention, urethral discharge, or persistent fever. Antibiotics were given to symptomatic patients only.
Sample Collection and Culture of Microorganisms
Urine specimen collection was implemented on the day of catheterization after completion of the catheterization procedure, every 7 days thereafter, on the day of removal, and on days when UTI infection or symptoms were suspected. Urine routine tests, including the urine strip (normal value: color is yellow, and clarity is clear) and urine sediment (normal value: 0-5 white blood cells (WBCs) per high-power field (HPF), urothelium cell < 1/HPF), were performed to confirm urine cleanliness. If the urine analysis was equal to or greater than 10 WBCs/HPF, then a urine culture was obtained within 24 hours of a positive urinalysis but before antibiotics were administered. Urine microbial culture was also carried out if a participant exhibited signs or symptoms of infection such as fever. After disinfecting the port with 10% iodine tincture for at least 30 seconds and then scrubbing it with 75% alcohol, the urine specimens were obtained using a sterile needle with syringe from the sampling port of the indwelling UC. All specimens were sent to the laboratory within 1 hour of collection. UC tips were not cultured and were not acceptable for diagnosing UTI.
Definition of Urinary Tract Infection
The surveillance protocols and the CAUTI definitions were performed according to the criteria published by the U.S. Centers for Disease Control and Prevention, which include symptomatic UTI (SUTI) and asymptomatic bacteriuria (ASB; Horan et al., 2008). CAUTI is a UTI that occurs in a patient with an indwelling UC in place within 48 hours before the onset of UTI. Data, including the dates and sites of infection, pathogens, and patient demographic information, were collected by trained infection control practitioners who had been blinded to patient group assignments. Reports of cases of CAUTI were also verified by an infectious disease specialist.
Statistical Analysis
The primary analysis was conducted on an intention-to-treat (ITT) basis. In addition, a per-protocol analysis was performed on patients with UCs indwelled for >= 15 days because of a medical indication. For categorical variables, a chi-square or Fisher's exact test was used to evaluate between-group differences. For continuous variables, the Student's t test was used for normally distributed data, and the Mann-Whitney U test was used for data that failed the normality assumption. Kaplan-Meier analysis was also used. Furthermore, relative risk (RR), incidence density ratio (IDR), and 95% confidence intervals (CIs) were calculated. The collected data were analyzed using IBM SPSS statistical software. All tests were two-tailed, and p < .05 was considered statistically significant.
Results
Patient Characteristics
Three hundred forty-one patients with indwelling UCs were enrolled as participants in this study (Figure 1). Of these, 94 (56.6%) in the control group and 91 (52.0%) in the intervention group were excluded from the per-protocol analysis. On the basis of the analyses of the host and indwelling catheter factors, no significant differences (p > .05) were found using goodness-of-fit analysis between those participants who remained in the study and those who had been excluded for protocol violations. Seventy-two participants (43.3%, 72/166) in the control group and 84 (48%, 84/175) in the intervention group were included in the per-protocol analysis during the 1-year study period (Figure 1).
The demographic and clinical characteristics of the patients in the two groups are shown in Table 1. The results of ITT analysis showed no significant differences (p > .05) in the other variables between the two groups with the exception of underlying illnesses (kidney disease, p = .01) and the frequency of separation of the junctions between the catheter and the urinary drainage system (22.9% in the control group and 5.1% in the intervention group, p < .01).
Incidence of Infections
Information regarding the types of UTIs and the UTI incidence for the two groups are shown in Table 2. In the ITT analysis, 25 control group participants (15.1%; 9.6 episodes/1,000 catheter-days) and 26 intervention group participants (14.9%; RR = 1.01, 95% CI [0.61, 1.68]; 9.6 episodes/1,000 catheter-days; IDR = 1.01, 95% CI [0.58, -1.74]) were found to have contracted CAUTI. In the per-protocol analysis, 16 control group participants (22.2%; 9.3 episodes/1,000 catheter-days) and 15 intervention group participants (17.9%; RR = 1.24, 95% CI [0.66, 2.34]; 7.7 episodes/1,000 catheter-days; IDR = 1.20, 95% CI [0.60, 2.43]) were found to have contracted CAUTI. Further stratification analysis of CAUTI contraction was performed in the ITT analysis, with SUTI found in 13 control group participants (7.8%, 5.0 episodes/1,000 catheter-days) and 14 intervention group participants (8.0%; 5.2 episodes/1,000 catheter-days; RR = 0.98, 95% CI [0.47, 2.02]; IDR = 0.97, 95% CI [0.46, 2.06]). However, in the per-protocol analysis, SUTI was found in nine control group participants (12.5%, 5.2 episodes/1,000 catheter-days) and five intervention group participants (6.0%; 2.6 episodes/1,000 catheter-days; RR = 2.10, 95% CI [0.74, 5.98]; IDR = 2.03, 95% CI [0.68, 6.04]). No major mechanical complications (e.g., cystitis, prostatitis, orchitis, pyelonephritis) were found in this study.
In the Kaplan-Meier estimator analysis, half of the urinary drainage system became unclean by the fourth day in the control group and by the 10th day in the intervention group, with no statistically significant intergroup difference indicated (p > .05). On the 14th day, uncleanliness of the urinary drainage system was found in 59% of both groups, whereas on the 19th day, the control group remained stable at 60% and the intervention group had increased slightly to 70% and remained stable afterward (Figure 2).
During the study period, the three most common CAUTI pathogens were yeast (10.6%), Escherichia coli (9.7%), and Enterococcus spp. (4.1%). A between-group comparison of the microbial distribution in the urinary drainage system showed no significant difference (p > .05).
Discussion
UCs with closed urinary drainage systems are regularly used in hospitalized patients who require catheterization. However, the frequency of replacing and operating these devices may be associated with an increased risk of contracting CAUTI. The results of the ITT and per-protocol analyses in this study support the study hypothesis that the rates of CAUTI, SUTI, and ASB would not be significantly different between patients who have their urinary drainage systems regularly replaced every 14 days and those who replace this system after a longer period (> 14 days).
In terms of the reporting on urinary drainage systems, several reports pointed out that more than 20% of patients with indwelling UCs became infected when the closed urinary drainage system was not handled properly (Chenoweth, 2014; Pratt et al., 2007; Warren, 1997). Furthermore, some researchers have noted problems between closed urinary drainage systems and CAUTIs. To investigate the influences on CAUTIs, they conducted studies on the addition of disinfectants and antibacterial agents to drainage bags or changed the design of the connection between the UC and the urinary drainage system. However, the interventions used in those previous studies were not effective in reducing infections, and thus, most guidelines do not recommend their related approaches (Conway & Larson, 2012). Therefore, adding antimicrobials or antiseptics into the drainage bag is not recommended as a method to reduce infection.
The issue of urinary drainage system replacement frequency has rarely been investigated. The daily and weekly bag-changing regimens were compared among 12 elderly catheterized patients over a 6-month period in one early study. The results found no significant difference in the average number of bacterial species isolated from each specimen between those patients on a daily bag-changing regimen (3.7 bacterial species) and those on a weekly regimen (3.9 bacterial species; p > .1; Gould et al., 2019; Pratt et al., 2007). Another study employed a randomized controlled method to compare the incidence of CAUTI, with 79 patients randomized into the "3-day replacement bag" group and 74 patients randomized into the "no replacement bag" group. They found that the incidence of SUTI (p = .7) and asymptomatic UTI (p = .9) was 13.9% and 36.7%, respectively, in the 3-day replacement group (mean indwelling = 10.1 days) and 10.8% and 36.5%, respectively, in the no-change group (mean indwelling = 9.5 days; Keerasuntonpong et al., 2003). However, these previous studies were affected by several important methodology-related limitations, including small population size, short replacement cycle, short indwelling catheter duration, and unclear definition of CAUTI.
The data collected in this study indicate that there was no statistically significant difference (p > .05) in the rates of CAUTI between the two groups. It is worth noting that the incidence of CAUTI in the 14-day group (control; 22.2%) was found to be 4.3% higher than that in the >= 15-day group (intervention; 17.9%) in the per-protocol analysis. In particular, the incidence of SUTI in the control group (12.5%) was 6.5% higher than that in the intervention group (6%), suggesting that replacing the urinary drainage system every 2 weeks is associated with a 2.1 increase in SUTI contraction risk. The results of this study support the recommendation of the Joanna Briggs Institute, which notes that no protective effect is gained from routine (as opposed to clinically required) drainage bag changes (Grade B: moderate support that warrants consideration of application; The Joanna Briggs Institute, 2010). Moreover, the results of this study also agree with previous recommendations that the catheter and urinary drainage system should be replaced based on clinical indications only (e.g., infection, obstruction, or compromise of the closed system; Gould et al., 2019).
Regarding the issue of urinary bag cleanliness, it was observed in this study that the rate of detection of impurities, sediment, or turbidity in the urine bags was similar in both groups. On the 14th day, both groups reported "unclean" conditions in almost two thirds of the specimens, whereas on the 19th day, the specimens with unclean conditions had increased by 10% in the intervention group, after which the proportion in the two groups remained stable. In other words, regularly replacing only part of the urinary drainage system in a complete catheterization system does not improve the cleanliness, as impurities, sediment, and turbidity may originate from the urinary system such as the bladder. Thus, the best strategy to improve this situation is to simultaneously remove both the urinary drainage system and the UC.
In patients with indwelling UCs, microbes in a urinary drainage system are an important source of intraluminal colonization. For example, if medical staff do not properly operate the closed system or if the urine bag is higher than the bladder, then urine with microbes from a contaminated collection bag or catheter-drainage tube junction may be returned to the bladder, leading to bacteriuria or infection (Clarke et al., 2020; Fekete et al., 2020; Rahimi et al., 2019). In this study, the pathogens cultured in the two groups were similar. The most frequent pathogens associated with CAUTI (combining both SUTI and ASB) found in this study were yeast and intestinal bacteria (Escherichia coli and Enterococcus spp.). Our data were similar to those reported in other studies (H. Chen et al., 2020; European Centre for Disease Prevention and Control, 2019; Fekete et al., 2020; Rahimi et al., 2019).
The strength of this study was that it provides evidence to help resolve concerns regarding existing clinical measures. Beyond having no significant influence on the CAUTI rate, the changes resulting from the appropriate replacement of the urinary drainage system may also reduce the time cost of the nursing staff and material costs as well as reduce medical waste-related burdens and the impact on the environment.
This study was potentially affected by several limitations. First, the nonrandomized design of this study may have resulted in heterogeneity bias in the distribution of potential risk factors in the control and intervention groups. Our data showed a different distribution of kidney disease in the two groups. However, the stratified analysis found no statistically significant effect on cleanliness and SUTI. Furthermore, other hosts and catheterization-associated risk factors between the two groups were similarly distributed. Thus, the confounding effects of those factors were also minimized. Second, 341 patients with an indwelling UC were enrolled over a 12-month period. However, because some patients' catheters were removed earlier than planned or they were discharged before the study was completed, the sample size in the per-protocol analysis may not be sufficient. Fortunately, there were no statistically significant differences in the analysis of related covariate factors between the included and excluded participants. Third, to detect urine clarity and possible infections, a urine culture was performed when the urine routine test showed >= 10 WBCs/HPF. Thus, the frequency of the culture was increased, which may also lead to an overestimation of ASB. However, this issue did not affect the comparison between the two groups. Finally, the study was performed at a single medical center and focused on patients who were staying in the infectious disease ward. The generalizability of the findings may thus be limited to patients in similar settings.
Conclusions
It is vitally important to implement best practices and minimize the risk of infection in patients. The results of this study found no significant difference in the incidence of catheter-associated complications between 14-day replacement interval and >= 15-day replacement interval patients. Regular replacement of the urinary drainage system only in the entire catheterization system was shown not to improve cleanliness. Therefore, the use of a urinary drainage system in a short-term (<= 30 days) indwelling catheter may be extended to coincide with the removal of that catheter. Nevertheless, patients with prolonged use of a urinary drainage system must be carefully examined for signs or symptoms of infection. In future studies, a randomized trial design should be conducted to reverify this finding and provide clinical personnel with evidence-based policy recommendations on changing urine bags.
Acknowledgments
This study was supported by a research grant from the Taipei Veterans General Hospital (V102C-140), Taipei, Taiwan. The authors thank the Department of Infection Control in the Taipei Veterans General Hospital for supporting data analysis.
Author Contributions
Study conception and design: YYC
Data collection: CCL
Data analysis and interpretation: YYC, CSC, IHC
Drafting of the article: YYC
Critical revision of the article: YYC
References