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Percutaneous tibial nerve stimulation safe, effective in treatment of OAB, study shows

Tuesday, April 20 2010 | Comments

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What's This? Percutaneous tibial nerve stimulation (PTNS) appears to be safe and effective relative to sham intervention in patients with overactive bladder (OAB), ruling out a placebo effect that might have been seen in previous studies which did not use a validated sham intervention, new data suggest.

Treatment for OAB generally starts with behavioral and pelvic floor therapies, followed by treatment with antimuscarinic agents, which are the mainstay of treatment, the investigators explained. However, adherence to this therapy is limited by lack of efficacy, side effects, and cost, and surgical treatments such as augmentation cystoplasty are invasive, they added.

PTNS has been used as early as 1987 for lower urinary tract symptoms, and some studies have shown highly favorable comparisons to pharmacotherapy in the treatment of OAB, the investigators said. However, these studies used an on/off design in implanted treatment responders, which did not allow for analysis of the impact of validated placebo response.

To evaluate this issue further, the investigators conducted a double-blind study of 220 adults with OAB symptoms that compared PTNS (Uroplasty Inc.'s Urgent PC system) with a validated sham intervention. Patients were randomized to receive PTNS or an inactive sham intervention. The primary endpoint was moderate or marked improvement of OAB symptoms in the 13-week global response assessment (GRA). Other endpoints included individual components of the GRA, 3-day voiding diary parameters, and OAB and quality of life questionnaires.

In an intent-to-treat analysis, 54.5% of subjects in the PTNS group showed moderate or marked improvement of OAB symptoms from baseline to 13 weeks based on the GRA versus 20.9% of subjects in the sham group who did so (P<.001). An as-followed completer analysis of those patients assessed at 13 weeks showed similar statistically significant results in favor of PTNS as compared with sham therapy (58.3% vs 21.9%).

Subjects in the PTNS group also demonstrated statistically significant improvements on all GRA subset symptom components as compared with subjects in the sham therapy group.

Daily results from the 3-day voiding diary showed that PTNS was statistically superior to sham therapy in reducing frequency, urinary urge incontinence episodes, nighttime voids, urgency episodes, and voids with moderate to severe urgency. Patients in the PTNS group had a statistically significant increase in voided volume from baseline to 13 weeks. Although no such increase was seen in the placebo group, the difference between the groups was not statistically significant.

Statistically significant improvements on the condition-specific OAB questionnaire symptom severity scores and quality of life scores were seen in the PTNS group. While statistically significant improvements on the short-form 36-item general health survey were seen in the PTNS group from baseline to 13 weeks in the physical and mental domain scores, the difference between the PTNS and placebo groups was not statistically significant.

In the PTNS group, 52% of subjects correctly identified their intervention versus 58% of patients in the sham therapy group who did so, confirming the validity of the sham model, the investigators said.

A total of 9 mild or moderate treatment-related events were seen from 6 patients in the PTNS group. In the sham group, no such treatment-related adverse events were recorded.

"The results of this study provide strong scientific evidence that the therapeutic effect of PTNS is due to the stimulation of the posterior tibial nerve and is not due to a placebo effect," the investigators concluded. "The compelling efficacy of PTNS as demonstrated in this trial, along with other recently published reports, should have a significant impact on the future clinical management of OAB," they concluded. (Peters KM, et al. J Urol 2010;183:1438-1443.)

Uroplasty provided support for the trial.

This information may concern a use that has not been approved by the Food and Drug Administration.

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