A clinical predictive model of renal injury in children with isolated antenatal hydronephrosis

Abstract

BackgroundAntenatal hydronephrosis (ANH) affects ∼1–5% of pregnancies. The aim of this study was to develop a clinical prediction model of renal injury in a large cohort of infants with isolated ANH.MethodsThis is a longitudinal cohort study of 447 infants with ANH admitted since birth between 1989 and 2015 at a tertiary care center. The primary endpoint was time until the occurrence of a composite event of renal injury, which includes proteinuria, hypertension and chronic kidney disease (CKD). A predictive model was developed using a Cox proportional hazards model and evaluated by C-statistics.ResultsRenal pelvic dilatation (RPD) was classified into two groups [Grades 1–2 (n = 255) versus Grades 3–4 (n = 192)]. The median follow-up time was 6.4 years (interquartile range 2.8–12.5). Thirteen patients (2.9%) developed proteinuria, 6 (1.3%) hypertension and 14 (3.1%) CKD Stage 2. All events occurred in patients with RPD Grades 3–4. After adjustment, three covariables remained as predictors of the composite event: creatinine {hazard ratio [HR] 1.27, [95% confidence interval (CI) 1.05–1.56]}, renal parenchyma thickness at birth [HR 0.78(95% CI 0.625–0.991)] and recurrent urinary tract infections [HR 4.52 (95% CI 1.49–13.6)]. The probability of renal injury at 15 years of age was estimated as 0, 15 and 24% for patients assigned to the low-risk, medium-risk and high-risk groups, respectively (P < 0.001).ConclusionOur findings indicate an uneventful clinical course for patients with Society for Fetal Urology (SFU) Grades 1–2 ANH. Conversely, for infants with SFU Grades 3–4 ANH, our prediction model enabled the identification of a subgroup of patients with increased risk of renal injury over time.

Conversations for the future in the follow-up of antenatally diagnosed renal pelvicalyceal dilatation

“…Of note, the odds for permanent kidney damage in dilatation > 15 mm or CAKUT diagnosis are impressively high (8.9 and 14.0 respectively) and these must receive appropriate visibility and clinicians' attention. The study findings regarding CKD appear in some discordance to Costa et al, which reports a somewhat higher risk of CKD surrogates at peri-pubertal age [5] (Table 1). Although important, it is not an easy task to explain these differences; the effect of cohort size and puberty may be two important factors.…”

“…The current study also expresses some noteworthy discordance with the long-term modelling study from Brazil [5] ( Table 1). The study which includes 447 participants had a much higher incidence of obstructive nephropathy (specifically PUJO), higher modelled incidence of CKD and composite events, including proteinuria and hypertension, as has been rightly acknowledged by the authors.…”

“…Nevertheless, the highlight of this study is the correlation to a lack of long-term kidney morbidity which few other studies comment on (Table 1). In perhaps the only other study to add to these data, Costa et al also report no CKD in the low-severity cohort (SFU 1-2) in their study [5]. Clinicians should feel more reassured by this.…”

“…Antenatally detected renal pelvic dilatation and/or antenatally detected hydronephrosis is associated with a definite health burden [1]. This brief editorial, which is drafted in response to the study by Herthelius et al, looks at the results of the reported long-term follow-ups [2][3][4][5], compares between similar studies and discusses the direct and indirect future implications of such precious data on healthcare.…”

Antenatally detected urinary tract dilatation: a 12–15-year follow-up

“…Only few studies have followed children with antenatally detected UTD for longer than a median of 2 years [5,7,8], and even fewer for longer than a median of 10 years [9,10]. In these studies, the included cases had a wide range of follow-up times [5,[7][8][9][10], and some of them only examined subgroups of children [7,8,10].…”