BACKGROUND: Lower Urinary Tract Dysfunction (LUTD) is a condition that affects children´s lives with physical, social, and psychological issues. Transcutaneous electrical nerve stimulation (TENS) offers a non-invasive treatment for LUTD using electrodes placed on the lower back to stimulate nerves involved in bladder control. While effective for a significant amount of patients, TENS success varies. Factors affecting nerve stimulation by TENS include skin impedance, current intensity, and the distance from the electrode to the target nerve. We hypothesize that the longer the distance from the electrodes to the sacral nerves, the worse the outcome. This study explores body mass index (BMI) as a potential predictor of TENS effectiveness in children with LUTD.
METHODS: This is a retrospective analysis of a prospective collected data. We included patients with LUTD who underwent parasacral TENS. We excluded patients with anatomical abnormalities of the lower urinary tract and neurogenic bladder. BMI was assessed and the symptoms were evaluated by the Dysfunctional Voiding Score System (DVSS). Multivariate analysis explored variables with p < 0.1. Variables significant (p < 0.05) were used to assess model accuracy (ROC curve, Hosmer-Lemeshow test) for identifying BMI's association with TENS outcomes. Treatment failure was assessed using ∆ Dysfunctional Voiding Score System (DVSS) 50 and 100 percentiles. The BMI was evaluated and classified by World Health Organization´s Z-score.
RESULTS: Seventy patients were included in the study, with a median age of 8 years (IQR 6-9), and 42 (60%) were female. The median BMI of the sample was 17.5 (IQR 14.7-22.2) and 24 patients (34.3%) failed treatment. In this sample, 33 patients had an elevated BMI (48.2%), of which 10 were overweight, 16 were obese, and 7 had severe obesity, according to the Z-score. Among the 24 patients who failed treatment, 9 had an elevated BMI (37.5%), while among those who succeeded in treatment, 24 had an elevated BMI (52.2%), p=0.11 and Pearson's correlation with R = 0.127. Considering 100% resolution of urinary symptoms as a positive outcome, 52 patients failed, of whom 21 (40.3%) had an elevated BMI, while among the 18 who succeeded, 12 (66.6%) had an elevated BMI, p=0.195 and Pearson's correlation R = 0.143.
CONCLUSIONS: Elevated BMI cannot accurately predict treatment failure with TENS in children and adolescents with LUTD.
