What are we Doing Wrong? The High Rate of Stone Recurrence in Children

What are we Doing Wrong? The High Rate of Stone Recurrence in Children IN this issue of The Journal Tasian et al (page 246) present an intriguing series investigating recurrent pediatric stone disease.1 Perhaps the most thoughtprovoking finding in this study was the dramatic reduction of stone recurrence in patients who completed 24-hour urine collection. Although the confidence interval was wide due to limited power, the association was strong. As studies have suggested (including this series with a 50% recurrence rate within 3 years of index stone), pediatric patients tend to present with a high stone recurrence rate.2,3 If this study finding truly reflects 24-hour urine testing as a preventive tool, one can only imagine a more essential role of 24-hour urine collection in monitoring and guidance for the management of pediatric urolithiasis in the future. On the other hand, if 24-hour urine collection becomes a part of the standard practice, one can hypothesize that more patients with metabolic abnormalities will be detected. In cases refractory to dietary modification medication would inevitably be involved in the discussion as intervention. It would be a significant challenge to justify the risks and benefits in prescribing longer term medications based on limited

higher level evidence of pharmacological interventions in the pediatric population. We should be cautious when interpreting the results of this study. Although well thought out and analyzed, it could not avoid the limitation of the original design as a single institution retrospective study. For example it was impossible to determine whether the associations were truly a reflection of causality or a biased estimate. Significant selection bias may exist in including more medically compliant patients/parents in the 24-hour urine collection completion group, resulting in a lower rate of stone recurrence. Therefore, this study should be viewed as hypothesis generating rather than hypothesis validating. Large scale multiinstitutional collaboration and prospectively collected data delineating the true impact of 24-hour urine collection and its clinical implications are warranted for future pediatric urolithiasis care. Hsin-Hsiao Scott Wang Division of Urologic Surgery Duke University Medical Center Durham, North Carolina

REFERENCES 1. Tasian GE, Kabarriti AE, Kalmus A et al: Kidney stone recurrence among children and adolescents. J Urol 2017; 197: 246.

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2. Pietrow PK, Pope JC IV, Adams MC et al: Clinical outcome of pediatric stone disease. J Urol 2002; 167: 670.

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3. Routh JC, Graham DA and Nelson CP: Epidemiological trends in pediatric urolithiasis at United States freestanding pediatric hospitals. J Urol 2010; 184: 1100.

http://dx.doi.org/10.1016/j.juro.2016.10.029 Vol. 197, 10, January 2017 Printed in U.S.A.