Objective: It has been assumed that a patient’s underlying baseline overactive bladder (OAB) incontinence severity is predictive of the resulting efficacy of pharmacological treatment. The objective of this study was to stratify and analyse the effects of baseline incontinence disease severity on the treatment outcome of the percentage of patients continent (PPC) during treatment with once-daily trospium chloride 60 mg extended release (XR).
Methods: A post hoc analysis was conducted on pooled data from two 12-week, randomised, double-blind phase III studies in the USA in which 1165 patients with baseline urgency, and an average of ≥ 1 urge urinary incontinence (UUI) episode/day and ≥ 10 toilet voids/day on a 3-day bladder diary, received once-daily trospium chloride 60 mg XR (n = 578) or placebo (n = 587). Patients were stratified by the mean number of UUIs/day (1.0, > 1.0–2.0, > 2.0–5.0 or > 5.0) at baseline. The efficacy parameter that was analysed was complete continence (defined as no UUIs on a 3-day bladder diary collected at week 12 of treatment).
Results: Baseline UUI levels were inversely correlated with the week 12 PPC (p < 0.0001). Post-treatment PPCs were higher with trospium chloride XR vs. placebo at all degrees of severity. Complete continence was achieved in 75% of trospium chloride XR recipients with 1.0 UUI/day at baseline and 48% of those with > 1.0–2.0 UUIs/day at baseline.
Conclusions: These findings support the assumption that baseline incontinence severity affects the likelihood of achieving continence from OAB therapy, and that patients with less severe OAB (e.g. 1 UUI/day) can expect higher ‘dry rates’ following treatment (e.g. up to 75%) than those with more severe OAB. This information can provide a useful tool for the physician and patient in establishing expectations during therapy.