Transcript Department Presentation Title

Dipstick Screening for Urinary Tract
Infection in Febrile Infants
Journal Club
Tuesday 15th July 2014
Charlotte Elder
Background
• SBI occurs in 10-15% 1-90 day olds
• UTI commonest cause SBI
• Utah
– Neonates – FSS and empirical Abx
– >28/7 – screen tests and ? admit
• NICE
– Infants <3/12 – urine testing
– Urgent M+C for infants <3/12
– Dipstick for children >3yrs
SCH guideline (7.1)
“Children younger than 2 years of age:
– Urgent microscopy and culture preferred method for diagnosing
UTI
– Dipstick analysis may be unreliable”
• Nitrites
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–
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Urinary micro-organisms reduce nitrate to nitrite
Nitrate needs to be in contact with bacteria for “some time”
Not all bacteria
Too quick in under 2s?
• Leucocytes (LE)
– LE enzyme contained in WBC
– UTI not the only cause of pyuria
• Evidence base?
Systematic review
• 6 studies
• Dipstick signif less good in < 2yrs
• LR
– +LR 38.5 vs 7.6
– -LR 0.13 vs 0.34
Mori et al. Acta paediatrica 2010;99:581-584
The Clinical Question
Population
Children less than 2 years with suspected UTI
Intervention
Dipstick urine testing or urine microscopy
Comparison
Urine culture
Outcome
Accurate diagnosis of UTI
Aim
Comparing performance of urine
dipstick alone with urine microscopy
and with both tests combined as a
screen for UTI in febrile infants aged
1 - 90 days.
Methods
• Retrospective observational study
• July 2004 – December 2011 (7.5 yrs)
• Multi-centre (23 hospitals)
• Same diagnostic equipment and database
• Patients identified from database
– Febrile infants and age
– Reason for visit
– Admitting diagnosis
– ICD-9 and coding
Methods
• Age 1-90 days
• Catheterised urine – 10mls
– Dipstick
– Microscopy of centrifuged urine
– Culture
• Medical records r/v if UTI but dipstick negative for
outcome (29-90 days)
Definitions - cultures
• Positive for UTI
– ≥1 pathogen
– ≥50,000 CFU/ml (half the “classic” definition)
• Negative for UTI
– No bacterial growth
– Growth of contaminant only
• <105 CFU/ml common skin GU flora
– Multiple bacteria each <105 CFU/ml
• Equivocal
– Urine pathogens 10,000-49,000 CFU/ml
– Excluded from analysis
Definitions – dip/micro/combo
• Positive for UTI - dipstick
– LE positive
– Nitrite positive
– ≥ trace
• Positive for UTI - microscopy
– >10 WBC per hpf
– ≥ 1 bacteria per hpf
• Positive UTI – combined
– Positive dipstick OR
– Positive microscopy
Results
Study
flow chart
Results
6394 febrile infants
770 UTI (12%)
5624 no UTI
6394 febrile infants
1745 (27%)
neonates
4649 (73%)
29-90 days old
p = <0.001
Sensitivity = true positives
p = <0.001
Specificity = true negatives
p = <0.001
p = <0.001
p = <0.001
p = <0.001
Example
• Prevalence in 29-90 day old infants = 11.9%
• 1000 febrile infants
– 119 culture positive UTI
– Dipstick alone
• 90.4% true positive pick up (108/119) – 9.6% false negative
• 6.2% false positive rate (55 of 881)
– Combined urinalysis
• 94.8% true positive pick up (113/119) – 5.2% false negative
• 10.9% false positive rate (96 of 881)
• 8 treated who don’t have UTI for every 1 infant missed
Critical appraisal
• Does the study address a clearly focused question?
• Did the study use valid methods to address the Qu?
• Are the valid results of the study important?
• Are the valid, important results applicable to our local
population?
• Were all clinically important outcomes considered?
• Are the benefits worth the harms/risks/costs?
Summary and Conclusion
Good to rule out UTI
CLINICAL BOTTOM LINE
Can dip infants’ urine?