273 Efficacy of Sacral Nerve Stimulation for Treating Slow Transit Constipation: A Randomised, Double-Blind, Placebo-Controlled, 2 Phase Crossover Study

Abstract

Sacral nerve stimulation (SNS) is a potential treatment for constipation refractory to standard therapies. Uncontrolled studies have shown promise, however, there have been no randomized controlled studies of its efficacy. Aim: In patients with slow transit constipation (STC), we evaluated the efficacy of suprasensory and subsensory SNS compared with sham, in a prospective, 18 week randomised, double-blind, placebo-controlled, 2 phase crossover study. The primary outcome measure was the proportion of patients who, on more than 2 days/ wk for at least 2/3 weeks, reported a bowel movement associated with a feeling of complete evacuation . (ANZ CT Registry; 00347680). Method: A caluclated 50 patients were needed to detect a 20% increase in response from sham(80% power 95% confidence). Following a 3 weeks of temporary peripheral nerve evaluation (PNE) all patients underwent a permanent implantation. Patients were then randomized into a double blind, cross-over study in which subsensory and suprasensory stimulation were compared to sham stimulation (Fig1). All patients kept daily stool dairies. Quality of life (QoL; SF36) was measured at the end of each treatment arm .Results: Of 59 patients with scintigraphically confirmed STC and no evidence of rectal evacuation disorder enrolled (4 male; 44 ± 15 yrs), 33% met the primary outcome measure during the PNE. 55 patients went on to permanent SNS implanted and were randomized into cross over study. The proportion of patients that satisfied primary outcome measure did not differ between suprasensory (30%) and sham (21%) stimulation nor between subsensory (25%) and sham (25%) stimulation. PNE did not provide an indicator of treatment success with only 8/16 PNE responders also responding suprasensory stimulation. In the SF36 only general health and and emotional well being improved during suprasensory stimulation (P=0.02). Conclusion: In patients with refractory STC, SNS did not improve the frequency of complete bowel movements over the 3-week active period, but did result in a modest improvement in general health. Secondary outcomes (pain, bloating, laxative-free days) and longer term responses of primary outcomes are awaited. (Supported by NMHRC Australia and Medtronic Australasia/USA). Cross-over design