Urodynamic interpretation in children with spina bifida: pitfalls and disagreements
Stacy T. Tanaka, MD MS1, Jonathan C. Routh, MD MPH2, Elizabeth B. Yerkes, MD3, Duong D. Tu, MD4, Christopher Austin, MD5, John S. Wiener, MD2, Kathryn A. Smith, RN, MN, DrPH6, David B. Joseph, MD7, Jennifer J. Ahn, MD8, M. Chad Wallis, MD9, Tonya Williams, PhD10, Charles Rose, PhD10, Michelle A. Baum, MD11, Kimberly Newsome, MPH10, Earl Y. Cheng, MD3.
1Vanderbilt University Medical Center, Nashville, TN, USA, 2Duke University Medical Center, Durham, NC, USA, 3Lurie Children's Hospital of Chicago, Chicago, IL, USA, 4Texas Children's Hospital, Houston, TX, USA, 5Oregon Health Sciences University, Portland, OR, USA, 6Children's Hospital Los Angeles, Los Angeles, CA, USA, 7University of Alabama - Birmingham, Birmingham, AL, USA, 8Seattle Children's Hospital, Seattle, WA, USA, 9Primary Children's Hospital, Salt Lake City, UT, USA, 10Centers for Disease Control and Prevention, Atlanta, GA, USA, 11Boston Children's Hospital, Boston, MA, USA.
Background: The urodynamic findings of detrusor sphincter dyssynergia and leak point pressure > 40 cm H2O are associated with bladder hostility and renal deterioration in individuals with spina bifida. Recognizing both the importance and limitations of urodynamics in the urologic management of this patient population, we critically assessed how often and why pediatric urologists disagreed on whether a baseline newborn urodynamic study showed a hostile bladder.
Methods: The Urologic Management to Preserve Initial Renal Function (UMPIRE) Protocol for Young Children with Spina Bifida is an iterative quality improvement protocol that follows a cohort of newborns at multiple centers in the United States. Baseline newborn urodynamics are obtained at or before 3 months of age. Individual urodynamic parameters are collected. The bladder is also characterized as normal, safe, intermediate or hostile based on protocol definitions. To assess reliability, four pediatric urologists from UMPIRE sites volunteered to review de-identified urodynamics tracings and fluoroscopy images. They then recorded whether they agreed with the original interpretation. Each study was reviewed by specialists at the original site and urologist at two of four outside sites such that each study was reviewed by 3 pediatric urologists from 3 different clinical sites. The Cochran-Armitage test was used to evaluate evaluate agreement from 2015-2017 over time.
Results: A total of 132 newborn studies from 8 clinical sites underwent review. The original reading of the studies were 5 normal, 40 safe, 59 intermediate, and 28 hostile. Overall, all 3 reviewers agreed on 58% (77/132) of studies. This proportion did not improve over time (2015: 55% (20/36); 2016: 60% (39/65); 2017: 59% (17/29) (p=0.32)). Of the 5 studies originally read as normal, all 3 reviewers agreed in 0 studies. One reviewer disagreed with the original interpretation for 3 studies. Both reviewers disagreed with the original interpretation for 2 studies. Of the 40 safe studies, all 3 reviewers agreed in 15 (38%) studies. One external reviewer disagreed with the original interpretation in 14 (35%) studies. Both external reviewers disagreed with the original interpretation in 11 (28%) studies. Of the 59 intermediate studies, all 3 reviewers agreed in 46 (78%) studies. One external reviewer disagreed with the original interpretation in 12 (20%) studies. Both external reviewers disagreed with the original interpretation in 1 (2%) study. Of the 28 hostile studies, all 3 reviewers agreed in 16 (57%) studies. One external reviewer disagreed with the original interpretation in 8 (29%) studies. Both external reviewers disagreed with the original interpretation in 4 (14%) studies.
Conclusions: The ability to replicate the characterization of bladder status through urodynamic studies and to reliably identify hostile bladders is low and changes little over time, even among high-volume centers of excellence. This study emphasizes the importance of continued efforts to standardize urodynamics techniques and their interpretation.
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