To systematically review and synthesize published literature on sacral neuromodulation for the treatment of urinary urgency, frequency and urge urinary incontinence.
MATERIALS AND METHODS:
Vanderbilt University's Evidence-based Practice Center was contracted by the Agency for Healthcare Research and Quality to review the literature on the Management of Overactive Bladder, including sacral neuromodulation. Literature published in English from January 1966 to October 2008 and indexed in PubMed, MEDLINE®, EMBASE and CINAHL were included. All references from key articles were hand-searched to identify additional studies. Two reviewers separately evaluated each abstract to evaluate for inclusion or exclusion. Articles selected for inclusion were then reviewed in full by two reviewers to determine if inclusion criteria were met. Discordance was resolved by third-party adjudication. Studies with fewer than 50 participants were excluded, as were studies with less than 75% women or a lack of relevance to overactive bladder.
Eleven studies on sacral neuromodulation met inclusion criteria: one RCT, two prospective cohorts, and eight case series. Study designs were generally weak, with six of the studies involving subject duplication from multiple sites. Seven of the studies did not restrict the study population to overactive bladder, compromising generalizability. The one RCT demonstrated a statistically significant benefit for sacral neuromodulation over usual care for the reduction of episodes of incontinence per day (average reduction of 7.1 episodes compared to a 2.1 increase among subjects who had failed medical management). Six case series reported a decrease in urge incontinence episodes of 51% to 80% daily. The length of follow-up ranged from six months to five years. Urinary frequency decreased between 31% and 45% consistently across all of the studies, regardless of study design; with most follow up ranging 6 to 24 months. One prospective case series found a 33% decrease in mean voids per day at one year, dropping to a 23% decrease at 5 years. Three studies found an increase in the mean voided volume of 78 to 108 mL per void. Two studies found that sacral neuromodulation had a beneficial effect on quality of life. In the early studies, there was an average of 1.1 to 1.7 adverse events per participant. Advances in technology have decreased this rate and more recent studies report 0.1 to 0.5 events per participant. Pain, lead migration or problems with the lead, infection and explantation of the device were the most common adverse events. Pain at the implantable pulse generator site occurred in 15.4% to 27% of the cases. Infection occurred in 1.9% to 6.1% of participants.
Sacral neuromodulation can provide modest improvement in rates of urinary frequency and urge incontinence, and in some instances improves quality of life. Additional research is needed to establish the circumstances under which sacral neuromodulation is an appropriate treatment choice, and to address whether the higher rate of adverse events seen with these techniques is outweighed by the symptom benefit.