What’s New with VCUG’sReview of AAP UTI Guidelines 2011

James Listman, MD

The big deal

• UTI has become the most frequent source of occult and serious bacterial infection in young children due in no small part to the effectiveness of immunizations, namely to H. influenzae and S. pneumoniae

The Good ol’ Days

• Historically about 1/3 of kids with UTI were determined to have vesicoureteral reflux

• Vesicoureteral reflux was BAD• Hence, vesicoureteral reflux should be stamped

out!• Therefore, the prior guidelines in 2009 stated

that a VCUG was indicated in every infant with UTI. – In fact, some of the people on this committee argued

in publications that a renal ultrasound was not particularly useful so could be abandoned!

Not so fast…

– Not all reflux is created equal

– Advent of prenatal US made it apparent that most if not all babies with CKD from reflux were born that way.

– But can’t UTI cause renal scarring?

– Yes, incidents is ~5% for fist time UTI (pyelonephritis) and goes up exponentially with number of episodes.

Why do we care about renal scars?

• Significant risk for developing malignant hypertension by young adult hood. Risk highest if bilateral scarring present.

• So you’re saying (no I’m saying) we should prevent scarring?

• Yes!

• How do we do that? Good question!

Back to the Good Ol’ Days

• Prophylactic antibiotics, right?

• That is the question. Lets dig deeper…

Recurrence of UTI/Pyelonephritis in infants 2-24 months of age with and without prophylaxis

0.0% 10.0% 20.0% 30.0% 40.0% 50.0%

None

I

II

III

IV

No Prophylaxis

Prophylaxis

.14

.29

.95

1

.15

P

Percent Recurrence

Ref

lux

grad

e

Lies, damned lies and statistics

• Do These Data Disprove Benefit of Prophylaxis?– That’s not precisely what the statistics say (P values

prove nothing)

– There could be a small benefit for grade IV reflux (and even in patients without relfux).

– There could be an issue with compliance

– There could be an issue with how we do prophylaxis (ie, is there a way to reduce resident organisms)

• The better question is how much benefit might there be if we believe there is a difference?

Lets Assume for the moment

– Lets say we believe that prophylaxis does help for grade IV reflux…

• The NNT = 8 to prevent 1 infection in one year.

• The number of VCUG to find one grade IV refluxer is 10 (10% of case)

• Thus, would need about 80 patients to undergo first time VCUG to prevent 1 UTI in one year in a patient with grade 4 reflux.

Risk/Benefit

• Okay, if we do this, what substantive benefit is derived by preventing this one UTI in our hypothetical grade IV refluxer

• The number of VCUG’s to prevent one new renal scar for grade IV refluxers would be 800!

• At that level there is a chance that using the old recommendations could do more harm than good.

Waiting to do VCUG until 2nd UTI

Detection Rates (%)

After 1rst UTI(N = 100)

After 2nd UTI(N = 10)

No VUR 65 26

Grade I-III VURR 29 56

Grade IV VUR 5 12

Grade V VUR 1 6

Using new recommendations of waiting for second UTI cuts down on VCUG’s to 1/10th the original number!

Are we excluding anybody?

• Yes, don’t we care about the worse grade of reflux, V.

– Grade V reflux has highest recurrence rate of UTI.

– Most consider it risky or unethical to try that experiment, although, the data would argue the risk is smaller than expected.

• Neonates – 2 months old

– Some of the studies used 1 month olds, but N is small

– Expert also believe there is higher risk in this group

RBUS: Mitigating Risk

• The subcommittee recommends RBUS following first UTI so as not to miss the rare kid with significant urologic abnormalities.

– Those grade V refluxers might very well be identified by US.

– Other obstructive processes that get missed by prenatal US.

– Ideally done after UTI has resolved (get sooner if fever not improving by 2 days).

2010 Cochran DB Review

• Performed meta-analysis of antibiotic prophylaxis and various procedural interventions– Found trend for less UTI with ATB prophylaxis, but P

above 0.05.

– ATB use did correlate with less renal scarring – huh?

– Procedures correlated with reduced symptomatic UTI but no change in scarring compared with ATB alone

• Conclusion (mine): I suspect ATB impart a small benefit as does reflux repair. The problem is the NNT is relatively high.

Summary

• Recommendations for UTI management have evolved

• Diagnosis now requires Positive culture (<50,000 colonies) and Postive UA (leukocytosis/nitrates)

• RBUS done ideally after infection clears (should do by day 2 if not clinically improving).

• VCUG not done for first UTI, unless RBUS shows significant plumbing issues and/or renal abnormality

• Will do ~ 10 fold fewer VCUG’s by waiting for second febrile UTI

• The data strongly support this balanced approach.