Defining Efficacy in the Treatment of Overactive Bladder Syndrome

Patients seek treatment for overactive bladder syndrome (OAB) due to poor quality of life, and perceived improvement in quality of life (QOL) from medical therapy is multifactorial. Many feel that efficacy/success of medical therapy for OAB should not be linked to improvements in 1 or 2 endpoints, but instead should be linked to patient expectation and QOL improvement. Ideally, once patient-centered goals are defined, outcomes should be correlated with relief of symptom(s), patient satisfaction, and goal attainment expectations as a result of treatment.Key words: Overactive bladder syndrome, Patient-centered treatment, Medical therapy for OABOveractive bladder syndrome (OAB) as defined by the International Continence Society (ICS) consists of the presence of urinary urgency, with or without urge incontinence, usually with frequency and nocturia.¹ The prevalence rates in both men and women in the United States is estimated at approximately 17%.¹ The total cost of OAB for the year 2000 has been estimated at $12.6 billion.² This cost is made up of diagnostic, treatment, routine care, consequence, and indirect costs from loss of productivity. Due to prevalence and cost of this condition, there are significant resources being utilized to develop treatments that improve patient quality of life (QOL) and reduce the financial burden to society.OAB is a medical problem largely due to its negative impact on daily QOL. The subjective impact of urinary frequency and urgency (with/without urge incontinence) on psychosocial and physical well-being is an important aspect of caring for this group of patients. The severity and degree of bother associated with the symptoms of OAB can directly influence a person’s mobility, degree of social isolation, impairment in work-related activities, disruption of sleep, impairment of domestic and sexual life, and result in depression.³ Patients may also develop extreme coping strategies including self-imposed fluid restrictions, avoidance of social events and travel, and dependence on protective undergarments. OAB not only affects the lives of patients, but also the lives of their caretakers and their QOL. Thus, many patients and their caretakers seek out treatments that will help provide improvement in these aspects of their lives. Unfortunately, relatively few data are available on the effect of current treatments on patient QOL.Most clinical trials evaluating the efficacy of medications and other treatments related to OAB define success as efficacy based on improvements in primary and secondary clinical endpoints. Generally, these clinical endpoints include reduction in incontinence episodes, micturition frequency, urgency measures, and nocturia. The potential problem with this is that clinically significant changes in these parameters compared with placebo may not result in meaningful change in QOL for the patient or the caretaker and may result in discontinuation of medication. Failure to achieve meaningful changes in quality may be related to the fact that a particular symptom is not adequately changed or an adverse event impacts negatively on QOL. A strong argument for this is the poor rate of medication persistence seen in managed care patients with OAB that are significantly lower than reported discontinuation rates from clinical trials.^4–7 Persistence rates for OAB drugs range from 8% to 29% in studies with at least 1 year of follow-up.^4,5,7–9 When comparing extended-release (ER) formulations with immediate-release (IR) formulations, no significant difference was seen in persistence rates after multivariate analysis.⁶ In a study evaluating patient reasoning for OAB medication discontinuation, only one-third of patients cited a single reason for discontinuation, with most citing multiple reasons with a mean of 2.3 reasons.¹⁰ The more common reasons included: 46.2%, “didn’t work as expected”; 21.1%, “side effects”; 17.2%, cost; and 11.2%, “another medication/medical condition required me to stop.” Patient adherence with prescribed therapy is affected by perceived benefit, pill burden, complexity of dosing schedule, memory lapses, and adverse events.¹¹With patients seeking treatment for OAB due to poor QOL and perceived improvement in QOL from medical therapy being multifactorial, it is clear why many believe that efficacy/success of OAB medication probably should not be linked to improvements in 1 or 2 endpoints, but instead should be linked to patient expectation and QOL improvement. Ideally, once patient-centered goals such as the ability to perform certain tasks are defined, outcomes should be correlated with relief of symptom(s), patient satisfaction, and goal attainment expectations as a result of treatment. We need to establish more clear-cut evidence of how a myriad of factors affect treatment response.