Several options exist for managing overactive bladder (OAB), including electrical stimulation (ES) with non-implanted devices, conservative treatment and drugs. Electrical stimulation with non-implanted devices aims to inhibit contractions of the detrusor muscle, potentially reducing urinary frequency and urgency.

To determine the effectiveness of: ES with non-implanted electrodes compared with placebo or any other active treatment for OAB; ES added to another intervention compared with the other intervention alone; different methods of ES compared with each other.

We searched the Cochrane Incontinence Group Specialised Register, which contains trials identified from the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE, MEDLINE In-Process, ClinicalTrials.gov, WHO ICTRP and handsearching of journals and conference proceedings (searched 10 December 2014). We searched the reference lists of relevant articles and contacted specialists in the field. We imposed no language restrictions.

We included randomised or quasi-randomised controlled trials of ES with non-implanted devices compared with any other treatment for OAB in adults. Eligible trials included adults with OAB with or without urgency urinary incontinence (UUI). Trials whose participants had stress urinary incontinence (SUI) were excluded.

Two review authors independently screened search results, extracted data from eligible trials and assessed risk of bias, using the Cochrane Collaboration’s ‘Risk of bias’ tool.

We identified 51 eligible trials (3443 randomised participants). Thirty-three trials did not report the primary outcomes of subjective change in OAB symptoms. The majority of trials were deemed to be at low or unclear risk of selection and attrition bias and unclear risk of performance and detection bias. Lack of clarity with regard to risk of bias was largely due to poor reporting.

Twenty-three trials (1654 participants) compared ES with no active treatment, placebo or sham treatment. Moderate-quality evidence indicated that OAB symptoms were more likely to improve in people receiving ES than with no active treatment, placebo or sham treatment (relative risk (RR) for no improvement 0.54, 95% confidence interval (CI) 0.47 to 0.63). Moderate-quality evidence indicated that similar numbers of people receiving ES and no active treatment, placebo or sham treatment experienced adverse effects.

Eight trials (542 participants) compared ES with conservative treatment. Very low-quality evidence suggested no evidence of a difference between ES and PFMT or PFMT plus biofeedback in OAB symptoms (RR for no improvement 0.79, 95% CI 0.51 to 1.21 and 0.97, 95% CI 0.60 to 1.57 respectively). There was no evidence of a difference between ES and conservative treatment with regard to adverse effects.

Sixteen trials (894 participants) compared ES with drug treatment (probanthine, tolterodine, oxybutynin, propantheline bromide, solifenacin succinate, terodiline, trospium chloride, terodiline). Moderate-quality evidence indicated that OAB symptoms were more likely to improve with ES than drug treatment (RR for no improvement 0.66, 95% CI 0.48 to 0.90). Low-quality evidence suggested a greater risk of adverse effects with oxybutynin (RR 1.26, 95% CI 1.07 to 1.49) and with tolterodine (RR 1.51, 95% CI 1.21 to 1.89) than with ES. There was insufficient evidence of a difference between ES and trospium hydrochloride (RR 0.73, 95% CI 0.43 to 1.25).

Eight trials (252 participants) compared ES combined with another treatment versus the other treatment alone, two trials (48 participants) compared ES plus conservative treatment with no active treatment, placebo or sham treatment and six trials (361 participants) compared different types of ES. None of these comparisons had sufficient evidence to indicate any differences between the treatment groups in terms of OAB or adverse effects.

Moderate-quality evidence suggested that ES improved OAB-related quality of life more than no active treatment, placebo or sham treatment. There was insufficient evidence of any difference between ES and any other treatment with regard to quality of life.

There was insufficient evidence to determine if the benefits of ES persisted after the active treatment period stopped.

Electrical stimulation appeared to be more effective than both no treatment and drug treatment for OAB. There was insufficient evidence to determine if ES was more effective than conservative treatment or which type of ES was more effective. This review underlines the need to conduct well-designed trials in this field measuring subjective outcomes and adverse effects.