Current Treatment of Overactive Bladder in Patients with Diabetes and Obesity
A review and assessment of five current research studies for the efficacy in managing overactive bladder syndrome, particularly in patients with metabolic disease.
October 2019
Volume 1, Issue 8

Patient-Reported Drug Preferences in Management of OAB Symptoms

While mirabegron was considered more tolerable, and improved quality of life symptom scores in the PREFER trial, the researchers sought to quantify treatment preferences.

Health Qual Life Outcomes. 2018;16(1)::69

Patients often seek treatment for overactive bladder (OAB) syndrome when their quality of life is significantly adversely affected. Given their dire discomfort, they are more likely to adhere to treatment when they perceive improvements in their symptoms.

As reported in the PREFER drug tolerability study,based partly on scores from the Medication Tolerability scale of the OAB Treatment Satisfaction questionnaire (OAB-s), mirabegron was better tolerated and associated with significantly fewer anticholinergic side effects than extended-release tolterodine (tolterodine-ER), but this difference did not translate into patient preference for mirabegron. Therefore, the investigators set out to explore patient-reported outcomes and responder rates to identify differences in outcomes that might predict treatment success on mirabegron as compared to extended-release tolterodine (tolterodine-ER).1

The PREFER study was a phase 4 crossover trial in which treatment-naïve participants with OAB took mirabegron or tolterodine-ER for eight weeks, underwent a two-week washout period, then took the same or the other medication for another 8 weeks.  

Patient-reported outcomes were assessed using two meansurement methods:

  • The OAB-S measures the multidimensional concept of treatment satisfaction using five independent scales (OAB Control Expectations, Impact on Daily Living with OAB, OAB Medication Tolerability, OAB Control, Satisfaction with OAB Medication), as well as five single-item overall assessments (Patient’s Fulfillment of OAB Medication Expectation, Interruption of Day-to-Day Life Due to OAB, Overall Satisfaction with OAB Medication, Willingness to Continue OAB Medication, and Improvement in Day-to-Day Life Due to OAB Medication).
  • The 33-item OAB questionnaire (OAB-q) assesses the effects of treatment on health-related quality of life, including social interaction, coping, sleep, and extent of symptom bother. The single-item Patient Perception of Bladder Condition (PPBC) evaluates participants’ perception of their bladder problems.

Study participants completed the OAB-q, PPBC, and the OAB-S-Interruption of Day-to-Day Life Due to OAB both at baseline and at each follow-up visit. They completed the OAB-S premedication questionnaire (OAB Control Expectations, Impact of Daily Living with OAB) only at the baseline visits for each treatment period. All other questionnaires were completed during the follow-up visits.

Baseline scores on the OAB-S premedication questionnaire, the OAB-q, and the PPBC indicated moderate levels of symptom bother, moderate problems with bladder condition and quality of life, and a significant disruption to daily activities. Responders were defined as participants showing minimally important differences for the OAB-q and an OAB-S Medication Tolerability of 90 or higher.

Improvements over time and the adjusted mean change in scores at the end of treatment were similar between mirabegron and tolterodine-ER for the OAB-S Impact on Daily Living with OAB, OAB Control, and Satisfaction with OAB Control scales; four of the five single-item OAB-S assessments; the OAB-q; and PPBC.

Similarly, the magnitude of slight decreases in Willingness to Continue OAB medication scores were similar for the two drugs. At each visit, however, the percentage of responders for the OAB-S Medication Tolerability and each OAB-q subscale was higher for mirabegron than for tolterodine-ER (Table 1). These comparisons were not tested for significance.

Patient tolerability to common overactive bladder syndrome treatments

Thus, even though the average improvement over time in patient-reported outcomes was comparable between mirabegron and tolterodine-ER, a higher proportion of participants reported clinically relevant improvements in medication tolerability, health-related quality of life during mirabegron treatment, and perceptions of their bladder condition. These results were consistent with changes observed in studies that included treatment-experienced patients.

The PREFER study was funded by Astellas Pharma Inc.

Expert Commentary Emphasizes Use of Patient-Reported Outcomes in Treatment Planning

Noting a recent trend, patient-reported outcomes (PROs) have been employed to distinguish “clinically meaningful improvement” from “statistically significant improvement.” For example, clinically meaningful progress is typically conveyed as the minimally important difference (MID), and defined as: “the smallest difference in score in the domain of interest that patients perceive as beneficial, which, in the absence of troublesome side effects and excessive costs, would mandate a change in patient management.”3,4 

Calculating the MID has enabled tresearchers to group patients according to any reported attainment in treatment benefit (responders) or not (non-responders). Due to the chronicity of overactive bladder syndrome and the dynamic nature of the condition, patients’ perceptions of improvement is paramount. Therefore, measuring PROs is also important since the objective measures of improvement (e,. measures of urgency, frequency, and incontinence episodes) are frequently similar among different treatment options.

The PREFER study is one such example;2 objective outcomes measures derived from bladder diaries in trial participants were similar for individuals on tolterodine and those given mirabegron. However, responder analyses on the OAB-q scale subscales and OAB-S Medication Tolerabilty Score favored treatment with mirabegron, suggesting a greater potential for patients to achieve clinically meaningful improvements in QoL, perception of their bladder condition, and tolerability with mirabegron.2  


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Drug Preferences for Treatment of Overactive Bladder—PREFER Trial
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