Neurogenic bladder associated with spina bifida disease remains a major cause for mortality or morbidity due to kidney damages. 
However, we currently do not know which urodynamic findings are associated with an higher risk of upper tract damages (UUTD) in spina bifida patients. The objective of the present study was to evaluate urodynamic findings associated with functional kidney failure and/or with morphological kidney damages. 

The objective of the present study was to evaluate urodynamics findings associated with UUTD.

A large single-center restrospective study was conducted in our national referral center for spina bifida patients using our patients’ files. All urodynamics curves were assessed by the same examinator. Functional and/or morphological evaluation of the upper urinary tract were done at the same moment as the urodynamic exam (between 1 week before and 1 month after). Kidney function was assessed using creatinine serum levels or 24 hours urinary creatinine levels (creatinine clearance) for walking patients, or with the 24h urinary creatinine level for wheelchair‐users.

We included 262 spina bifida patients in this study. Fifty-five patients had a poor bladder compliance (21.4%) and 88 of them had detrusor overactivity (33.6%). The primary outcome of interest was the presence of UUTD on imaging at the time of the initial evaluation. The other outcome was kidney insufficiency (defined as eGFR < 60 mL/min).
Two groups of patients were done : no UUTD vs UUTD on imaging. 

Twenty patients had a stage 2 kidney failure (eGFR < 60 mL/min) and 81 patients out of 254 (30.9 %) had an abnormal morphological examination. There were three urodynamic findings significantly associated with UUTD: bladder compliance (OR=0.18; p=0.007), Pdetmax (OR=14.7; p=0.003) and detrusor overactivity (OR=1.84; p=0.03).
There were five clinical predictors associated with the risk of UUTD : male gender (OR=2.23; p=0.002), open spinal dysraphism (OR=2.7; p=0.0003), ventriculo-peritoneal shunt (OR=3.1; p=0.0002), being wheelchair-bound (OR=2.5; p=0.006) and urinary incontinence (OR=2.4; p=0.004).

In this large series of spina bifida patients, maximum detrusor pressure and bladder compliance are the main urodynamic findings determinants of UUTD risk and patients’ with those factors needs to be closely followed up.

UUTD is highly prevalent in adult spina bifida patients who did not undergo urinary diversion during childhood. In this patients’ population, maximum detrusor pressure and bladder compliance are the main urodynamic determinants of UUTD risk with optimal threshold of 21 cmH2O and 19 ml/cmH2O respectively. Several clinical parameters such as gender, type of spinal dysraphism, the mobility status or urinary incontinence are strongly associated with UUTD and may influence clinical management and follow-up protocols.