Variation in Definitions of Kidney Abnormality in Patients with Spina Bifida: A Systematic Scoping Review

Abstract

Purpose:We systematically reviewed the variability in definitions of kidney abnormality (KA) outcomes in individuals with spina bifida (SB).Materials and Methods:A systematic scoping review was conducted using MEDLINE, Embase™, Cochrane Library, CINAHL, PsycInfo®, Web of Science™ and ClinicalTrials.gov for articles from time of database inception to September 2020. No language or patient age restrictions were applied. Primary research articles involving individuals with SB where KA was assessed as an outcome were included. Means of assessing KA and defining KA severity were abstracted.Results:Of 2,034 articles found, 274 were included in the review. Most articles were published after 1990 (63.5%) and included pediatric-only populations (0–18 years; 60.5%). KA outcomes were identified by imaging-based anatomical outcomes (84.7%), serum-based outcomes (44.9%), imaging-based functional outcomes (5.5%), urine-based outcomes (3.3%) and diagnoses of end-stage kidney disease (2.6%) or chronic kidney disease otherwise unspecified (1.8%). Hydronephrosis was the most commonly used specific outcome (64.6%, 177/274) with 19.8% (35/177) of articles defining hydronephrosis severity. Hydronephrosis was used more frequently in articles with pediatric-only populations. Creatinine and cystatin-C were used in 82.1% (101/123) and 17.9% (22/123) of articles reporting serum-based outcomes, respectively, with 32.7% and 50.0% of articles defining estimated glomerular filtration rate (GFR) severity. Serum-based outcomes were more common in articles including adults >18 years. Measured GFR was assessed in 9.9% (27/274) of articles, with 44.4% (12/27) of articles defining GFR severity.Conclusions:Significant variability exists in how authors define KA with few specifically defining KA severity. Consensus and consistency in defining KA outcomes are needed.

This Month in Pediatric Urology

“…Rague et al (page 1184) from Chicago, Illinois in a systematic scoping review report on how kidney abnormality has been defined in the research literature for this population. 1 The authors found significant variability. Hydronephrosis was the most common outcome in children; serum-based outcomes were more common in adults.…”

The History of Renal Evaluation in Spina Bifida: Looking Back to Move Forward

“…2 This review points to areas of needed research and advancement in technology. 1 A more accurate and practical estimated GFR formula specific to this population with low muscle mass could allow physicians to better evaluate and track renal function over time. 3,4 Additionally, a method for estimating pressure at the level of the kidneys could potentially better predict future renal deterioration and inform intervention.…”

“…In their scoping review in this issue of The Journal, Rague et al (page 1184) give a thorough history of the methods that have been used to try to evaluate renal outcomes of people with spina bifida. 1 Not surprisingly, while some progress has been made, it has been slow. We remain heavily dependent on the use of ultrasound as a proxy for renal health.…”

“…The review also informs current studies. As the authors recommend, 1 researchers should pick consistent and explicit definitions when designing and reporting a study, such as which estimated GFR equation or hydronephrosis grading system is used. While there are established limitations to these, such as poor interrater reliability of hydronephrosis grading, 7 an established system is better than none and allows for comparisons between studies.…”