Tolterodine

Appell RA, Sand P, Dmochowski R, et al. Prospective randomized controlled trial of extended-release oxybutynin chloride and tolterodine tartrate in the treatment of overactive bladder: results of the OBJECT study. Mayo Clin Proc 2001; 76:358-63.

* BACKGROUND Anticholinergic medications are the mainstay of pharmacologic therapy for an overactive bladder (defined as urge incontinence, urgency, or frequency). Immediate-release oxybutynin and tolterodine (the most popular options) are equally effective, but tolterodine has a better side effect profile. The efficacy and tolerability of the newly developed extended-release oxybutynin is compared with tolterodine in this study.

* POPULATION STUDIED The investigators enrolled 378 mostly white (87%), mostly women (83%) participants aged 21 to 87 years (mean=59 years); 88% of the participants completed the study. The patients were required to experience between 7 and 50 episodes of urge incontinence per week and 10 or more voids in a 24-hour period. The study was conducted in 37 specialty outpatient-based practices across the United States. Previous exposure or response to therapy did not preclude participation. Patients were excluded if they had uncontrolled medical conditions, significant risk for urinary retention, or incontinence related to prostatitis, interstitial cystitis, urinary tract obstruction, urethral diverticulum, bladder tumor, bladder stone, prostate cancer, or urinary tract infection. Other exclusions included pelvic organ prolapse, pregnancy, and potential poor adherence to therapy.

* STUDY DESIGN AND VALIDITY This was a prospective randomized controlled trial (RCT) sponsored by the makers of oxybutynin. The study participants were treated for 12 weeks with either oxybutynin 10 mg per day or tolterodine 2 mg twice daily. Stratified randomization insured equal representation of mild incontinence ([is less than or equal to] 21 episodes weekly) and moderate to severe incontinence ([is greater than] 21 episodes weekly) within each treatment group. Study visits occurred at weeks 2, 4, 8, and 12. Each subject kept a 24-hour urinary diary documenting micturition frequency and the number and nature of incontinence episodes during the 7-day period before each study visit. The participants were asked at each visit about adverse events or unusual symptoms.

This study was well designed, avoiding bias with a double-blind double-dummy stratified randomization approach. Dropout rates were similar for the 2 groups. Formal intention-to-treat analysis was not possible, but the authors stated that analysis of partial data from dropouts was not different from reported results. The study may not be generalizable to most primary care populations, since patients were recruited exclusively from specialty practices. The authors adjusted for the nonsignificant baseline differences in incontinence frequency; this is statistically valid but not necessary in an randomized controlled trial. Without this adjustment, outcome differences between the 2 medications were substantially smaller and no longer statistically significant.

* OUTCOMES MEASURED The primary outcome measured was baseline versus end of study (week 12) episodes of urge incontinence. Total episodes of incontinence, micturition frequency, and medication side effects were secondary outcomes.

* RESULTS Both treatment groups showed a substantial reduction in urge incontinence, total incontinence, and micturition frequency. Urge incontinence decreased 76% in the oxybutynin-treated group and 68% in the tolterodine-treated group (P=.03). Total incontinence episodes in the oxybutynin-treated group dropped 75% from 28.6 to 7.1 episodes per week, while decreasing 66% from 27.0 to 9.3 episodes per week in the tolterodine-treated group. The net difference between the groups was 3.8 (P=.02) or 2.1 (P=NS) fewer episodes of incontinence per week with extended-release oxybutynin, adjusting or not adjusting for the baseline difference between the groups. Weekly bathroom trips declined by 27% in the oxybutynin-treated group versus 22% in the tolterodine-treated group (P=.02). Rates of side effects were similar for oxybutynin compared with tolterodine.

RECOMMENDATIONS FOR CLINICAL PRACTICE

Oxybutynin and tolterodine both produce a marked decrease in symptoms in patients with an overactive bladder. These medications have a similar cost ([is less than or equal to] $78 monthly) and side effect profile, but extended-release oxybutynin is modestly more effective than tolterodine. This small advantage may be important to patients in whom a decrease of 2 to 4 fewer episodes of incontinence per week represents a substantial improvement. However, the combination of anticholinergic medication and behavioral therapy provides an even greater benefit than pharmacotherapy alone.[1]

REFERENCE

[1.] Burgio KL, Locher JL, Goode PS. Combined behavioral and drug therapy for urge incontinence in older women. J Am Geriatr Soc 2000; 48:370-74.

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COPYRIGHT 2001 Gale Group