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Unnecessary urine testing is very common, especially in the emergency department.
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Unnecessary urine testing could lead to overtreatment and unnecessary costs.
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Reflex urine testing cancellation could prevent more than halve of microscopic analysis.
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Reflex urine testing cancellation could prevent almost a fourth of urine cultures.
Abstract
Background
Urinalysis and urine culture are two of the most commonly ordered tests. A positive urine test in asymptomatic patients often leads to overtreatment. Antimicrobials for asymptomatic bacteriuria is one of the most common unnecessary treatments. We aimed to explore the current ordering patterns of urinalysis and cultures.
Methods
This is a substudy of the multicentre RICAT-trial, a successful quality improvement project to reduce inappropriate use of intravenous and urinary catheters in seven hospitals in the Netherlands. Adult patients with a (central or peripheral) venous or urinary catheter admitted to internal medicine and non-surgical subspecialty wards were eligible for inclusion. Data were collected every other week during baseline (seven months) and intervention periods (seven months). The primary outcome was the proportion of urine cultures performed following a negative urinalysis, i.e. dipstick and/or microscopic analysis, within 24 h.
Results
Between September 2016 and April 2018, we included 3748 patients, of which 3111 (83%) were admitted from the emergency department. Urinalysis and/or urine cultures were obtained in 2610 (70%) of 3748 patients. 626 (23.7%) of 2636 urine cultures and 1351 (55.8%) of 2419 microscopic analysis were unnecessary performed after a negative urinalysis. Cancelling urine testing orders after a negative dipstick would have saved almost € 19.500 during the study period in these seven hospitals.
Conclusion
Unnecessary urine testing is frequent in non-surgical patients in the Netherlands. We need to take action to reduce unnecessary urinalysis and cultures, and thereby probably reduce overtreatment of asymptomatic bacteriuria.
Low-value care is defined as a test or treatment that is unlikely to benefit the patient given the cost, available alternatives, and preferences of patients, [
]. Reducing overuse is a key to improve quality of care and stop the expanding growth of healthcare costs. To confirm or exclude a urinary tract infection (UTI) urine cultures are only required when urinalysis is abnormal, i.e. dipstick or microscopic analysis, except in neutropenic patient. In addition, urine cultures are not recommended for the diagnosis of uncomplicated UTIs [
]. However, asymptomatic bacteriuria is a common condition, especially in women, elderly, patients with chronic indwelling catheters, and patients with diabetes [
]. As a result, the sensitivity of urinalysis and cultures for urinary tract infections is low in asymptomatic patients, and should therefore not be ordered in these patients. Despite clear evidence and guideline recommendations against treatment of asymptomatic bacteriuria, it has been shown that antibiotics for this condition is probably one of the most common unnecessary treatments. The results of a recent retrospective cohort study in 46 hospitals in the United States showed that 83% (2259/2733) patients with asymptomatic bacteriuria were treated with antibiotics [
]. Positive urinalysis and urine cultures with a bacterial colony count more than 100,000 CFU per high-power field were the main risk factors for overtreatment of asymptomatic bacteriuria in this study [
]. This is also reported in a qualitative study that determined the reasons for using antibiotics to treat ASB in the internal medicine in Switzerland [
]. So, unnecessary ordering of urinalysis and urine cultures, including routine screening, promotes inappropriate antimicrobial use.
Because urine cultures are only required after an abnormal urinalysis and unnecessary ordering of cultures promotes inappropriate antimicrobial use, we aimed to explore the current ordering patterns of urinalysis and urine cultures in medical patients in the Netherlands. Our hypothesis was that more than 15% urine cultures collected would be unnecessary, with the highest numbers in the emergency department [
We performed a substudy of our multicentre, interrupted time series and before and after study, entitled RICAT-study (Reduce Inappropriate use of intravenous and urinary CATheters), to reduce inappropriate use of intravenous and urinary catheters in the internal medicine and non-surgical subspecialty wards in seven hospitals (three university and four general hospitals) in the Netherlands [
De-implementation strategy to reduce inappropriate use of intravenous and urinary catheters (RICAT): a multicentre, prospective, interrupted time-series and before and after study.
]. We prospectively included adult patients who had a (central and/or peripheral) venous and/or urinary catheter. Data were collected from 1st September 2016 to 1st April 2018. Further details are described in the original study publication [
De-implementation strategy to reduce inappropriate use of intravenous and urinary catheters (RICAT): a multicentre, prospective, interrupted time-series and before and after study.
Ethical approval was obtained from Medical Ethics Research Committee of the Academic Medical Centre (Amsterdam, the Netherlands), with a waiver for individual informed consent. Local feasibility was approved by the local institutional review boards of all participated hospitals. The results are reported in accordance with the Strengthening the Reporting of Observational Studies in Epidemiology (STROBE) statement [
Adult patients admitted to internal medicine, gastroenterology, geriatrics, oncology, pulmonology wards, and all nonsurgical patients admitted to acute medical units, who had (central and/or peripheral) venous and/or urinary catheter(s) were eligible for inclusion. We excluded patients admitted for elective short stay, terminally ill patients, and patients who had previously been included in the study. Patients with chronic use of catheters, defined as having any catheters prior to the current admission, were also excluded. In addition to the in- and exclusion criteria of the RICAT-study, patients admitted for a kidney transplant were also excluded, since these patients routinely undergo frequent urinalysis and cultures for screening.
2.3 Outcomes
The primary outcome was the proportion of urine cultures obtained following a negative urinalysis (dipstick and/or microscopic analysis) within 24 h. We defined a negative urinalysis if all of the following results were absent [
]: nitrites and leukocyte esterase in a dipstick, and >5 leukocytes per high-powered field and an abnormal amount of bacteria, as defined by the local standard operating procedures of the laboratories, during the microscopic analysis. The secondary endpoints were the proportion of microscopic analysis obtained following a negative dipstick, the number of double dipsticks and double non-contaminated microscopic analysis obtained during the same day, and the costs of unnecessary microscopic analysis and urine cultures.
2.4 Statistical analysis
We summarized categorical data as frequency and percentage. Dipstick and microscopic analysis (together called urinalysis) obtained at the same day were analysed as one positive or negative urinalysis. Next, urinalysis and urine cultures obtained within 24 h were analysed as combined diagnostic tests. We did a subgroup analysis for urinalysis and urine cultures obtained from the emergency departments. Descriptive analyses were performed using IBM SPSS Statistics (version 25.0). The RICAT-study is registered at Netherlands Trial Register, trial NL5438.
3. Results
Between 1st September 2016 and 1st April 2018, we screened 6157 of the 7511 hospitalized patients for inclusion. 461 patients were missing, resulting in 5696 screened patients by direct observations, of which we included 3748 patients (Reasons for exclusion see Fig. 1). 3111 (83%) of the included patients were admitted from the emergency department. Other baseline characteristics are presented in Table 1. Urine diagnostics, i.e. urinalysis and/or urine cultures, were obtained in 2610 (70%) of 3748 patients.
We found different urine order sets in participating hospitals. None of the hospitals used reflex testing, which are tests that automatically results in the order of one or more secondary tests based on the result of the initial test. For example, reflex urine culture cancellation, which means that cultures are automatically cancelled if urinalysis is negative. In contrary, three participating general hospitals in clinical practice routinely obtained both dipstick and microscopy together.
In total 2636 urine cultures were obtained, of which 626 (23.7%) following a negative urinalysis. When patients admitted for neutropenic fever were excluded, 609 (23.6%) of 2576 urine cultures were deemed unnecessary. There was wide variation in unnecessary urine cultures between hospitals ranging from 12.1% to 31.6% (Table 2). In the subgroup analysis of the urine tests obtained from the emergency department, 357 (32.2%) of 1108 urine cultures were obtained following a negative urinalysis.
Table 2Urine cultures obtained after negative urinalysis.
We found that 1351 (55.8%) of 2419 microscopic analysis were obtained after a negative dipstick, and in the subgroup of emergency department these numbers were 589 (54.1%) of 1088. Next, 115 (3.1%) of 3663 dipsticks and 39 (1.6%) of 2419 microscopic analysis were obtained double during the same day. Double urinalysis in the emergency department occurred in 55 (3.3%) of 1684 dipsticks and 21 (1.9%) of 1088 microscopic analysis.
An introduction of a urine order set that only perform a microscopy and/or culture after a positive dipstick could prevent these unnecessary tests. In the seven participating hospitals this would result into a decrease of 626 cultures and 1351 microscopic analysis in non-surgical patients. In the Netherlands, the cost of a urine culture and microscopic analysis is respectively € 25,58 per culture and € 2,54 per microscopic analysis, [
] resulting into saving € 19.445 in these seven hospitals during the study period of 14 months.
4. Discussion
Unnecessary urinalysis and urine cultures were indeed frequent in non-surgical patients in the Netherlands. The highest prevalence was in the emergency department, where 32% of the urine cultures and 56% of the microscopic analysis were ordered unnecessary after a negative dipstick result. Urine order set with a reflex culture and microscopic analysis cancellation would result in a substantial reduction of urine testing and laboratory costs. This was successfully introduced in an academic medical centre in the United States, where a urinalysis reflex to urine cultures prevented 64% of urine cultures in all adult and paediatric inpatients [
There are multiple explanations for unnecessary urine testing. The most important explanation is probably that urine tests are quick and easy to obtain. It is common practice to order different tests in combination when urine is obtained from a patient, for example as part of the triage protocol in the emergency department, [
] but microscopy or cultures are not automatically cancelled after a negative dipstick. Furthermore, a focus group with five emergency department nurses and a survey of 169 residents and staff clinicians of a university hospital in the United States showed a lack of knowledge about appropriate indications for testing in physicians and nurses [
Reducing unnecessary culturing: a systems approach to evaluating urine culture ordering and collection practices among nurses in two acute care settings.
]. We found that a small percentage of urinalysis were double tests obtained during the same day. In our opinion, this is probably due to unclearness of registration in patient chart of an already ordered test.
Our results are similar to a retrospective chart review of two hospitals in the United States, where 50 (50%) of 100 urinalysis were determined unnecessary in patients admitted to internal medicine departments during the first 24 hours of medical care [
]. Unnecessary urine testing seems even higher in asymptomatic patients, since result of another study show that 78% (181/232) urinalysis and 35% (81/232) cultures were unnecessary obtained in asymptomatic patients admitted to a general medicine service in an academic centre in New Zealand [
]. In addition, a prospective 4-weeks cohort study in a tertiary care centre in Canada in 2015 showed that 62% (250/403) of medical patients had a urinalysis before admission, and 84% (211/250) of these patients were asymptomatic [
The main strength of this study is the multicentre design, which supports generalisation of our results. However, our study also has limitations. We report an underestimation of unnecessary urine testing, since we did not review the documented indications for urinalysis or cultures and we do not know how many patients were asymptomatic. Next, we included hospitalized patients from the RICAT-study. Since most admitted patients have a peripheral intravenous catheter during hospital stay (one of the inclusion criteria of the RICAT-study), the risk of selection bias is probably low. However, we did not evaluate the percentage of unnecessary testing in all patients that visited the emergency department.
Our study suggests that reflex culture and microscopic analysis cancellation after a negative dipstick result can lead into a substantial reduction of urine testing. A before and after study in one emergency department in the United States showed a reduction of 47% by retaining only urinalysis with reflex to microscopy and using nudges to order no other urine tests [
]. Retaining urinalysis with reflex to culture is an effective system change, that could sustainably reduce unnecessary testing. However, this will not impact unnecessary testing in asymptomatic patients. Antimicrobials for asymptomatic bacteriuria is one of the most common unnecessary treatments with a prevalence of 45% [
]. Therefore, we consider adequate diagnostics as an important part of antimicrobial stewardship and quality improvement projects should be implemented to reduce unnecessary urine testing and inappropriate treatment of asymptomatic bacteriuria, to achieve better patient care, lower antimicrobial resistance, and save costs. Since the emergency department had high prevalence of unnecessary testing, this should be the primarily focus. Our next step is to perform such a project (trial NL8242, trialregister.nl/trial/8242).
5. Conclusions
Unnecessary urinalysis and culture are very common in non-surgical patients in the Netherlands, especially in the emergency department. Reflex urine testing cancellation after a negative dipstick prevent more than halve of microscopic analysis and almost a fourth of urine cultures. This would be an important first step to reduce unnecessary urine testing in symptomatic patients, and would preferable be used in combination with intervention to stop urine testing in asymptomatic patients.
Funding
This work was supported by the Netherlands Organisation for Health Research and Development (ZonMw) [grant number 8392010022].
Contributors
BL and SG designed the study and arranged the funding application. BL and TvH recruited patients and collected data. BL analysed the data and wrote the first and final draft of the manuscript. All authors interpreted the data and revised the manuscript critically for important intellectual content. All authors read and approved the final manuscript.
Declaration of Competing Interest
The authors declare they have no conflict of interest.
Acknowledgments
We thank the Netherlands Organisation for Health Research and Development (ZonMw) for funding the study.
De-implementation strategy to reduce inappropriate use of intravenous and urinary catheters (RICAT): a multicentre, prospective, interrupted time-series and before and after study.
Reducing unnecessary culturing: a systems approach to evaluating urine culture ordering and collection practices among nurses in two acute care settings.
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