Faster clean catch urine collection (Quick-Wee method) from infants
Randomised controlled trial
- By: Neil Chanchlani
Faster clean catch urine collection (Quick-Wee method) from infants: randomised controlled trial by Jonathan Kaufman et al (BMJ 2017;357:j1341).
Objective—To determine if a simple stimulation method increases the rate of infant voiding for clean catch urine within five minutes.
Design—Randomised controlled trial.
Setting—Emergency department of a tertiary paediatric hospital, Australia.
Participants—354 infants (aged 1-12 months) requiring urine sample collection as determined by the treating clinician. 10 infants were subsequently excluded.
Interventions—Infants were randomised to either gentle suprapubic cutaneous stimulation (n=174) using gauze soaked in cold fluid (the Quick-Wee method) or standard clean catch urine with no additional stimulation (n=170), for five minutes.
Main outcome measures—The primary outcome was voiding of urine within five minutes. Secondary outcomes were successful collection of a urine sample, contamination rate, and parental and clinician satisfaction with the method.
Results—The Quick-Wee method resulted in a significantly higher rate of voiding within five minutes compared with standard clean catch urine (31% v 12%, P<0.001), difference in proportions 19% favouring Quick-Wee (95% confidence interval for difference 11% to 28%). Quick-Wee had a higher rate of successful urine sample collection (30% v 9%, P<0.001) and greater parental and clinician satisfaction (median 2 v 3 on a 5 point Likert scale, P<0.001). The difference in contamination between Quick-Wee and standard clean catch urine was not significant (27% v 45%, P=0.29). The number needed to treat was 4.7 (95% confidence interval 3.4 to 7.7) to successfully collect one additional urine sample within five minutes using Quick-Wee compared with standard clean catch urine.
Conclusions—Quick-Wee is a simple cutaneous stimulation method that significantly increases the five minute voiding and success rate of clean catch urine collection.
Trial registration—Australian New Zealand Clinical Trials Registry ACTRN12615000754549.
Why do the study?
Fever in children is a common presentation in primary and secondary care, and in about 20% of cases the presenting complaint has no obvious source.
Urinary tract infections should be considered in cases of unexplained fever in this age group, as they affect 5-7% of febrile children under 2 years of age, with girls more commonly affected than boys.
A urinary tract infection is simple to screen for and treat. It is investigated by performing a dipstick analysis on a urine specimen and, if positive, sending the specimen for culture. Guidelines from the National Institute for Health and Care Excellence advise that the choice of treatment for a urinary tract infection should be made on the basis of clinical suspicion, presence of nitrites, presence of leucocytes, and urine culture results. Obtaining a urine sample from a child isn’t easy, however, and is often a source of frustration for clinicians and parents.
It is best practice to have a “non-contaminated” urine sample, so attaching a bag to the skin surrounding a child’s genitalia is not usually acceptable. Suprapubic aspirates and “in/out” catheterisations have fallen out of fashion because of the invasiveness of the procedures.
The authors of this study say previous guidelines and research advise doctors to use a non-invasive, quick, and gentle method for urine collection, but no solution is offered. As a result, most parents sit with a bottle near the child waiting for the moment they need to wee.
In this study, the authors wanted to test whether the Quick-Wee method (gentle suprapubic cutaneous stimulation using gauze soaked in cold fluid on the bladder area) would hasten the excretion of urine, compared with the usual method of just waiting for the wee to arrive.
What did the authors do?
From September 2015 to April 2016 the authors performed a randomised controlled trial in a single tertiary paediatric emergency department in Melbourne, Australia. Eligible participants were aged 1-12 months, and a clean catch of urine was required in the clinical context.
An independent statistician randomised participants in a 1:1 ratio to receive either the intervention (Quick-Wee method) or usual care (standard clean catch urine with no additional stimulation).
Teaching of the Quick-Wee method took place via face to face education sessions with medical and nursing staff, and packs with cleaning supplies and equipment were prepared. Disclosure of either study arm occurred immediately before starting the intervention.
The primary study outcome was voiding of urine within five minutes (yes/no). Secondary outcomes included whether any urine was successfully caught in the pot or was missed (yes/no), contamination of clean catch urine sample obtained within five minutes (yes/no), and parental and clinician satisfaction with the urine collection method (using the 5 point Likert satisfaction rating scale).
The authors chose a superiority trial, which is a statistical test to show that one treatment is superior to another (see box 1).
Box 1: Trial design—which one to choose?
Deciding on which trial design to use depends on the question being asked and what the study authors want to show. Here is a list of the different types of trial design you can choose for a randomised controlled trial.
The aim of this type of study is to show a difference in effectiveness between two study arms, with one arm being superior to the other. If a difference is shown, the null hypothesis—that there is no difference between the two study arms—is rejected. If a difference in effectiveness is not shown, this does not necessarily mean the two arms are the same, as it might be caused by other factors such as lack of sample size achieving pre-specified power.
In a non-inferiority trial, the hypothesis is that the new treatment is not worse than the standard one in efficacy; it has the same benefit or no harm to the participants who took part in the study.
Development of a new way of delivering a treatment is often the reason why you might perform a non-inferiority trial. This can include testing the effectiveness of a treatment but could also cover other benefits such as cost reduction or increased patient access.
In an equivalence trial, the hypothesis tested is that a new treatment will perform not much worse and not much better than a standard intervention. Equivalence trials are useful in the development of second line drugs, showing therapeutic equivalence, and are most often used when comparing whether two or more formulations of a drug containing the same active ingredient give comparable blood concentrations with a pre-stated equivalence.
A sample size calculation, 177 in each study arm, was based on power calculations from previous baseline and pilot studies on voiding time in children. This information was used to determine the minimum difference between the two groups needed to show a clinically “superior” difference. A 15% increase in success rate of voiding within five minutes would indicate the Quick-Wee should be adopted into clinical practice.
What did the study find?
The researchers recruited 354 infants to the study, with a mean age of 5.4 months. Of those infants, 179 were allocated to receive the Quick-Wee intervention and 175 were allocated to receive usual care. The most common reason for collecting urine was fever of unknown origin (n=144, 42%).
In the intervention group, 31% (n=54) voided urine within five minutes compared with 12% (n=20) in the standard clean catch urine group; difference in proportions 19%, 95% confidence interval 11 to 28, P value <0.001 (see table). The intervention group were 2.6 times more likely to void within the five minute time slot than the standard care group.
Of the Quick-Wee group, 30% (n = 52) voided with successful catch compared with 9% (n=15) in the group receiving usual care; difference in proportion was 21%, 95% confidence interval 13 to 29, P value <0.001. The rate of contamination between groups was not statistically significant; numbers for this outcome were lower because not all urine samples were processed for culture. Both parents and clinicians reported a median satisfaction with the Quick-Wee method according to the Likert scale scoring system.
The results were clearly given and appropriate results reported in the context of superiority trial design. The team recruited the appropriate sample size and explained reasons for participant withdrawal and exclusion. There was no evidence of outcome switching.
|Outcomes||Quick-Wee (n=174)||% (95% CI)||Standard clean catch urine (n=170)||% (95% CI)||Difference in proportions or medians (95% CI)||P value|
|Voided <5 min||54/174||31 (24 to 39)||20/170||12 (7 to 18)||19 (11 to 28)||<0.001*|
|Voided and successful catch||52/174||30 (23 to 37)||15/170||9 (5 to 14)||21 (13 to 29)||<0.001*|
|Contamination†||12/44||27 (15 to 43)||5/11||46 (17 to 77)||18 (−14 to 50)||0.29‡|
|Median (interquartile range) parent satisfaction§||2 (1-3)||3 (2-3)||1 (0.6 to 1.4)||<0.001¶|
|Median (interquartile range) clinician satisfaction§||2 (1-3)||3 (2-3)||1 (0.6 to 1.4)||<0.001¶|
What does the study mean?
Overall, the Quick-Wee method is a more effective way to obtain a clean catch urine sample from infants compared with usual care.
The Quick-Wee method showed a statistically significant increase in voiding and successful urine collection compared with standard clean catch urine, with no difference in contamination rates and high parent and doctor satisfaction.
Although the Quick-Wee method was effective, it did not work within five minutes 69% of the time. It is likely that parents and clinicians will still have to wait some time for the wee to arrive.
A strength of the study is that the Quick-Wee method did not require additional staff or consumable resources. Medical and nursing staff, alongside parents, carried out the intervention, and the only equipment needed was gauze and saline.
Weaknesses of the study include a lack of blinding of the treatment arm—which was unavoidable—and that the intervention group included only children between 1 and 12 months of age. Obtaining a urine sample in pre-continent children beyond 1 year of age can be challenging, so it would be useful to know if the results can be applied to older children who are not yet toilet trained.
Future research should also look at what part of the Quick-Wee method coaxes the wee out: is it the cold fluid or the stimulation itself? The Quick-Wee method uses a circular pattern or rubbing using gauze while the child is lying supine. Other stimulation techniques or positions might be more effective, however. Another area to explore could be how to reduce contamination rates in the samples collected, which might be achieved by better cleaning of the skin before starting the procedure.
As a medical student or junior doctor, using the Quick-Wee method might help you make a diagnosis more quickly next time you see a child with fever of unknown origin or suspect a urinary tract infection. Since publication of the original article, our paediatric department has tried and tested the Quick-Wee method with good results.Neil Chanchlani, specialist trainee in paediatrics
Whittington Health NHS Trust, UK
Competing interests: None declared.
Provenance and peer review: Commissioned; not externally peer reviewed.
- Baraff LJ. Management of fever without source in infants and children. Ann Emerg Med 2000;36:602-14. doi:10.1067/mem.2000.110820 pmid:11097701.
- Robinson JL, Finlay JC, Lang ME, Bortolussi R. Canadian Paediatric Society, Infectious Diseases and Immunization Committee, Community Paediatrics Committee. Urinary tract infections in infants and children: Diagnosis and management. Paediatr Child Health 2014;19:315-25.pmid:25332662.
- National Institute for Health and Care Excellence. Urinary tract infection in under 16s: diagnosis and management, 2007. https://www.nice.org.uk/guidance/cg54.
- Sedgwick P. What is a superiority trial?BMJ 2013;347:f5420 doi:10.1136/bmj.f5420.
- Sedgwick P. What is a non-inferiority trial?BMJ 2013;347:f6853 doi:10.1136/bmj.f6853.
- Sedgwick P. Equivalence trials. BMJ 2013;346:f184 doi:10.1136/bmj.f184.
- Published: 06 November 2017
- DOI: 10.1136/sbmj.j2955