Long-term efficacy of duloxetine in women with stress urinary incontinence

OBJECTIVE To assess the maintenance of efficacy of duloxetine beyond 3 months, using data from several long-term, open-label studies, as the efficacy of duloxetine 40-mg twice daily for treating women with stress urinary incontinence (SUI) for up to 3 months has been established in several randomized, placebo-controlled clinical trials. PATIENTS AND METHODS Data from 1424 patients (Cohort A) enrolled in three 12-week, placebo-controlled clinical trials and their uncontrolled, open-label extensions, and in one uncontrolled, open-label study, were used to assess long-term continuation rates and continued efficacy based on responses to the validated Patient Global Impression of Improvement (PGI-I) scale for up to 30 months. Data from another 2758 patients (Cohort B) enrolled in an additional placebo-controlled study and its open-label extension were used to assess PGI-I ratings, reductions in incontinence episode frequency (IEF) recorded on urinary diaries, and the relationship between PGI-I ratings and reductions in IEF for up to 72 weeks. RESULTS In Cohort A, the duloxetine continuation rate at 1 year was 42.5%. At 12, 24 and 30 months, most (83%, 83% and 88%, respectively) patients in Cohort A who continued treatment rated their incontinence in one of the three 'better since starting treatment' PGI-I categories. Both the median IEF reductions (50-77%) and the PGI-I 'better' ratings (70-88% of patients) remained fairly consistent over 72 weeks in Cohort B. Finally, IEF reductions increased with increasing PGI-I ratings (approximate to 46% for 'a little better', 75% for 'much better' and 95% for 'very much better') over the first year of treatment. CONCLUSION The benefits of duloxetine were maintained in patients who continued treatment for up to 30 months. However, these favourable results need to be interpreted cautiously, as many patients discontinued treatment and those with better responses are more likely to continue taking medication.