Overactive bladder syndrome is a chronic condition encompassing the bothersome storage symptoms of urgency, with or without urge incontinence, usually with frequency and nocturia. Therefore, effective treatment of OAB must result in a reduction meaningful to the patient in all of these symptoms. This review of the data clearly shows that treatment with once-daily solifenacin 5 and 10 mg is associated with significant improvements in all of the symptoms of OAB. Indeed, >25% of solifenacin-treated patients experienced resolution of urgency, >50% of solifenacin-treated patients achieved continence, and at least one-third of solifenacin-treated patients experienced ‘normalisation’ of micturition frequency to eight or fewer voids per day by study endpoint. Treatment with both doses of solifenacin was also well tolerated by patients, with a few discontinuations due to AEs. If one acknowledges the importance of urgency as a pivotal symptom in this symptom complex; then clearly the high resolution and improvement rates may well be due to solifenacin's impact on the key symptom of urgency (2
Clearly, pharmacotherapy for OAB should not only improve symptoms, but also be tolerable, both of which will contribute to treatment persistence. One very effective measure of this ‘clinical effectiveness’ is assessment of QoL. Two of the four trials described in this analysis measured QoL changes (10
), using the KHQ (14
). Solifenacin significantly improved KHQ scores from baseline in nine of 10 domains compared with placebo, demonstrating statistically significant improvements in patient QoL (15
). The clinical relevance of these improvements to patients was determined using a scale based on a global rating of patient-perceived treatment benefit, and perceived disease impact (15
). When using the following definition of clinical meaning: MID ≤ 5 percentage point change from baseline; it was shown that patients who were treated with both 5 and 10 mg solifenacin demonstrated a statistically significant and clinically meaningful MID improvement from baseline in almost all KHQ domains, compared with patients receiving placebo. These improvements in QOL are likely to have contributed to the high persistence rates with solifenacin described in the present analysis (approximately 90% for patients receiving solifenacin). Similarly, high persistence rates have also been observed with longer-term treatment with solifenacin. In a 40-week, open-label extension of two of the studies included in this analysis, 81% of patients remained on solifenacin treatment for the full treatment period (17
). Furthermore, patient satisfaction with treatment efficacy and tolerability was high (74% and 85%, respectively) when assessed at the end of the extension study (17
The differences in the methodology used to record efficacy data (e.g. different study populations, different inclusion and exclusion criteria, different ways to measure and define urgency, and varying diary durations) and the selective presentation of data for symptom reduction, make it difficult and indeed academically questionable whether one can compare the results presented here with those of other published clinical trials. However, globally allowing for these misgivings, solifenacin appears to compare favourably to other antimuscarinics with respect to treating urgency and all of the other symptoms of OAB (18
). This drug is the first antimuscarinic for which there are published reports of improvements in all the key symptoms of OAB – frequency, urgency, incontinence and nocturia. Other publications of pivotal trial data for other antimuscarinic agents have reported data for some, but not all, of these symptoms (18
When considering the current published literature, there are few data available that report the ‘normalisation’ rates for OAB symptoms (18
). Most reports only provide this information for incontinence rates and do not present similar results for the proportion of patients who achieve cessation of urgency and nocturia, or normalisation of micturition frequency (<8 micturitions per 24 h). Symptomatic outcome measures such as this should be considered to be an essential facet of the assessment of treatment efficacy and should, therefore, be of keen interest to both clinicians and other healthcare providers in determining the clinical effectiveness and utility of different antimuscarinics.
In conclusion, solifenacin's efficacy has clearly been demonstrated in published studies for all symptoms of the OAB complex, with a high degree of tolerability and patient benefit. Whilst it is interesting to speculate that the symptom improvements may be driven by the favourable impact that solifenacin has on urgency, clearly, further studies using more accurate measures of patient perceived outcome are necessary to compare this agent to other antimuscarinics. Recently published results from the STAR study have provided a head-to-head comparison between solifenacin and tolterodine ER (22
). This study suggested that flexible dosing with both 5 and 10 mg solifenacin is more effective in reducing OAB symptoms such as urgency, incontinence, urge incontinence and improving volume voided, as well as improving patient perception of bladder condition, when compared with the highest (and recommended) dose of tolterodine ER (4 mg). The flexibility associated with solifenacin dosing may further increase its efficacy, as well as allowing treatment regimens to be designed for the needs of the individual patient, thus improving patient compliance and satisfaction (24
). Although the occurrence of common antimuscarinic AEs was greater with solifenacin-treated patients than with tolterodine-treated patients, the rate of patient discontinuation was low with solifenacin use, and comparable with tolterodine (23
), due to the high rate of patient satisfaction. Patient satisfaction is also high with the long-term use of solifenacin (17
). Further head-to-head comparison studies with other antimuscarinic OAB therapies are needed before definitive conclusions can be drawn.