Sample Size, Power, and Risk of Misclassification in Pediatric Urology Hospital Rankings

J Urol. 2021 May 13;101097JU0000000000001844. doi: 10.1097/JU.0000000000001844. Online ahead of print.

Abstract

Purpose: We investigated 2019 and 2020 U.S. News & World Report methodologies of assessing pediatric urology surgical revision rates for distal hypospadias, pyeloplasty, and ureteral reimplantation to evaluate statistical power and misclassification risks.

Materials and methods: Median annual volumes of distal hypospadias, pyeloplasty, and ureteral reimplantation procedures by hospital from 2016 to 2018 were calculated using the Pediatric Health Information System® database. U.S. News & World Report 2019 and 2020 methodologies were assessed to calculate power required to detect differences between hospitals and risk of hospital misclassifications.

Results: Median (IQR) annual hospital procedure volume was 72 (43-97) for distal hypospadias procedures, 19 (9-34) for pyeloplasties, and 35 (19-50) for ureteral reimplantations. Based on 2019 methodology, in order to achieve 80% power 764 cases/hospital are required to distinguish between a 1% vs 3% surgical revision rate, 1,500 cases/hospital are required to distinguish between a 3% vs 5% revision rate, and 282 cases/hospital are required to distinguish between a 1% vs 5% revision rate. Based on 2020 methodology, 98.0% of hospitals do not have adequate ureteral reimplantation volume to achieve full points even when reporting no revisions; similarly, 66.0% do not have adequate pyeloplasty volume, and 10.9% do not have adequate distal hypospadias volume. Risks of misclassification exceed 50% in several instances among hospitals reporting distal hypospadias and pyeloplasty revisions using both 2019 and 2020 methodology.

Conclusions: Based on median-volume hospitals, current U.S. News & World Report methods for classifying revision rates for distal hypospadias, pyeloplasty, and ureteral reimplantation have insufficient power and are at high risk for misclassification.

Keywords: hypospadias; pediatrics; reoperation; urology.