Positive outcomes with first onabotulinumtoxinA treatment persist in the long term with repeat treatments in patients with neurogenic detrusor overactivity.

OBJECTIVE: To examine whether response to first treatment with onabotulinumtoxinA is predictive of long-term treatment outcome in patients with neurogenic detrusor overactivity (NDO).

PATIENTS AND METHODS: Patients with NDO who were enrolled in a 3-year extension study (after a 52-week phase III study) received onabotulinumtoxinA 'as needed', based on fulfilment of prespecified retreatment criteria. This post hoc analysis included patients who received only the 200-U dose during the phase III and extension studies. Data on mean percent reduction from baseline in urinary incontinence (UI) episodes at week 6 after the first treatment were analysed, and the patients were stratified into three response groups: <50% (group 1; n = 33), 50-74% (group 2; n = 23), and 75-100% (group 3; n = 139). The following were assessed: change from baseline in mean percent UI reduction; proportions of patients who achieved ≥50% and 100% UI reduction after each subsequent treatment, and patients who achieved ≥50% UI reduction after all subsequent treatments; change from baseline in Incontinence Quality of Life (I-QOL) total summary score; and the proportion of patients who achieved or exceeded the minimally important difference (MID; +11 points) in I-QOL score. Adverse events (AEs) were also assessed.

RESULTS: The majority of the patients (83.1%; 162/195) experienced a ≥50% UI reduction after onabotulinumtoxinA treatment 1. Baseline characteristics were largely similar across the groups. After treatment 1, the mean percent reduction in UI remained consistent in subsequent treatments 2-6 for patients in response group 2 (range: 64.5-83.5%) and group 3 (range: 79.4-88.0%), but increased for those in the low response group (range: 36.3-60.3%). After treatment 1, the proportion of patients who achieved ≥50% reduction in UI episodes was consistent with subsequent treatments 2-6 in group 2 (range: 75.0-100%) and group 3 (range: 87.3-97.1%), but increased in the low response group (range: 48.3-72.7%). Even among those who achieved a low response after treatment 1, 37.9% of patients achieved ≥50% UI reduction in all subsequent treatments. Improvements in I-QOL scores in groups 2 and 3 were consistently 2-3 times the MID. In the low response group, at least 50% of the patients achieved or exceeded the MID with treatments 2-6. AEs were similar across all response groups and consistent across repeated treatments.

CONCLUSION: Patients with NDO with a ≥50% UI reduction after their first onabotulinumtoxinA treatment continued to experience consistent improvements in UI and quality of life with subsequent treatments over the duration of 4 years. A <50% UI reduction after first treatment did not necessarily predict low response with subsequent treatments. Thus, these results underscore the importance of attempting at least a second treatment with onabotulinumtoxinA before deeming patients unsuitable for onabotulinumtoxinA therapy.