Sacral nerve stimulation (SNS) may provide long-term symptom relief to patients suffering from chronic constipation. Patients are currently selected for SNS using a 2-week peripheral nerve evaluation (PNE) comprising stimulation by temporary leads. However, only 40% of test responders receive long-term benefit from treatment meaning that healthcare costs per successfully treated patient are too high. The primary objective was to assess tined-lead testing to predict benefit from SNS for chronic constipation.
A randomized double-blind sham-controlled cross-over design evaluated enhanced PNE (ePNE) using tined quadripolar electrode leads over 6 weeks. The design differentiated between patients with discriminate and indiscriminate responses to testing. A score improvement of 25% or more was considered to be a positive response within a stimulation period. The primary outcome was the proportion of patients showing a reduction of at least 0.5 in constipation symptom score at 6 months.
A total of 45 patients were randomized, of whom 29 (64.4%) were test-phase responders. Of these, 27 were implanted providing permanent SNS. During ePNE, seven (18%) were discriminate responders, 22 (56%) were indiscriminate responders and 10 (26%) were nonresponders. Six patients were withdrawn during the test phase because of infection or noncompliance. At 6 months, there was no significant difference in primary outcome between discriminate and indiscriminate responders (60 vs. 57%, P=0.76). The study was terminated prematurely because of a persistent infection rate of 10 (22%) during ePNE of which nine (20%) were severe.
ePNE is a poor predictor of treatment response at 6 months. This suggests a strong and persistent placebo response during both SNS PNE and treatment. An extended 6-week PNE poses a high risk of infection.
Departments of aNeurogastroenterology
bGeneral and Colorectal Surgery, County Durham and Darlington NHS Foundation Trust
cDurham University, Durham
dDepartment of Colorectal Surgery, North Tees and Hartlepool NHS Foundation Trust, Stockton
eInstitute of Health and Society
fNewcastle Clinical Trials Unit, Newcastle University
gDepartment of Colorectal Surgery, Newcastle University Teaching Hospitals, Newcastle upon Tyne
hDepartment of Colorectal Surgery, Gateshead Health Foundation Trust, Gateshead
iQueen Mary University of London, London
jDepartment of Health Economics, Warwick Medical School, Warwick University, Warwick, UK
Correspondence to Yan Yiannakou, MD, Darlington Memorial Hospital, Hollyhurst Road, Darlington, County Durham, DL3 6HX Durham, UK Tel: +44 191 333 2333; fax: +44 191 333 2685; e-mail: firstname.lastname@example.org
Received May 25, 2018
Accepted July 26, 2018