Urodynamic (UD) measurements are widely used to inform diagnosis, therapeutic decision-making, and treatment evaluation in patients with neurogenic detrusor overactivity (NDO); however, their reproducibility, validity, and responsiveness remain poorly characterised. This analysis aimed to evaluate the reproducibility, convergent validity, and responsiveness to abobotulinumtoxinA (aboBoNT-A) of UD measurements in patients with neurogenic lower urinary tract dysfunction (NLUTD).

This post-hoc analysis used data from two phase 3, double-blind studies, CONTENT1 (NCT02660138) and CONTENT2 (NCT02660359), evaluating the efficacy and safety of aboBoNT-A in adults with NDO performing clean intermittent catheterization [1,2]. Patients with a confirmed diagnosis of multiple sclerosis or spinal cord injury and documented NDO were randomized to receive placebo or aboBoNT-A. Patients who underwent UD testing (in accordance with International Continence Society recommendations) at baseline and post-treatment at Week 6 for at least one UD measurement of interest were included. UD measurements of interest included maximum detrusor pressure (MDP) during storage, bladder volume at first involuntary detrusor contraction (IDC), maximum cystometric capacity (MCC), and occurrence of IDCs. Ongoing analyses are evaluating bladder compliance, a key variable in this population. UD measurement reproducibility was evaluated in patients receiving placebo, using test–retest variability assessments between baseline and Week 6 measurements (Bland–Altman plots for continuous measurements; shift table for IDC occurrence). Intraclass correlation coefficients (ICC) were calculated to evaluate reproducibility of continuous measurements. Convergent validity was assessed using correlations between UD measurements and clinical outcomes (weekly number of incontinence episodes, incontinence-quality of life questionnaire total score, total 24-hour voided volume) for all patients at baseline, Week 6, and for change from baseline to Week ‍6. Responsiveness of UD measurements to treatment was assessed for patients who received aboBoNT-A using Glass’s delta effect size (ES) and standardized response mean (SRM).

Overall, 420 patients were included (n=137 placebo group, n=283 aboBoNT-A group). In patients receiving placebo, ICCs (95% confidence limit) between baseline and Week 6 quantitative measurements were 0.77 (0.69–0.83) for MDP, 0.58 (0.46–0.69) for volume at first IDC and 0.68 (0.58–0.76) for MCC. Bland–Altman plots evaluating test–retest reproducibility showed a mean difference close to 0, wide limits of agreement and random scatter with few outliers for MDP, volume at first IDC and MCC (Figure 1A). In the shift analysis, 93.7% of patients with IDCs at baseline remained IDC-positive at Week 6. Only 6.3% transitioned from IDC-Present to IDC-Absent, and none developed new IDCs (Figure 1B). UD convergent validity generally showed weak-to-moderate correlations with clinical outcomes at baseline, Week 6 and change from baseline to Week 6 (maximum correlation coefficient -0.4304). In the aboBoNT-A group MDP, volume at first IDC and MCC showed high responsiveness to treatment (ES: 1.02, SRM: 0.99, ES: 1.44, SRM: 0.96, and ES: 1.22, SRM: 0.94, respectively). Shift in IDC status from baseline to Week 6 in the aboBoNT-A group also showed a high responsiveness to treatment. Nearly half of patients (131/267, 49.1%) exhibited resolution of IDCs by Week 6.

In the placebo group, ICCs between baseline and Week 6 quantitative measurements indicated good reproducibility for MDP, and moderate reproducibility for volume at first IDC and MCC. MDP, volume at first IDC and MCC showed acceptable test–retest reproducibility, with variability consistent with expected biological and procedural variation in UD measurements. IDCs showed strong test–retest reproducibility. In the aboBoNT-A group, MDP, volume at first IDC, MCC and IDC occurrence were found to be responsive UD markers of treatment effect.

These results strengthen the evidence base for UD measurements as diagnostic tools and outcome measures for studies evaluating NLUTD treatments. Ongoing analyses are evaluating patient subgroups, and correlations between UD measurements and clinical outcomes.

Denys P et al. Neurourol Urodyn 2023;42:153–67.
Kennelly M et al. Eur Urol 2022;82:223–32.