title: A capsaicin (8%) patch in the treatment of severe persistent inguinal postherniorrhaphy pain: a randomized, double-blind, placebo-controlled trial.
abstract: BACKGROUND
  Persistent pain after inguinal herniorrhaphy is a disabling condition with a lack of evidence-based pharmacological treatment options. This randomized placebo-controlled trial investigated the efficacy of a capsaicin 8% cutaneous patch in the treatment of severe persistent inguinal postherniorrhaphy pain.
  
  
  METHODS
  Forty-six patients with persistent inguinal postherniorrhaphy pain were randomized to receive either a capsaicin 8% patch or a placebo patch. Pain intensity (Numerical Rating Scale [NRS 0-10]) was evaluated under standardized conditions (at rest, during movement, and during pressure) at baseline and at 1, 2 and 3 months after patch application. Skin punch biopsies for intraepidermal nerve fiber density (IENFD) measurements were taken at baseline and 1 month after patch application. Quantitative sensory testing was performed at baseline and at 1, 2, and 3 months after patch application. The primary outcome was comparisons of summed pain intensity differences (SPIDs) between capsaicin and placebo treatments at 1, 2 and 3 months after patch application (significance level P < 0.01).
  
  
  RESULTS
  The maximum difference in SPID, between capsaicin and placebo treatments, was observed at 1 month after patch application, but the pain reduction was not significant (NRS, mean difference [95% CI]: 5.0 [0.09 to 9.9]; P = 0.046). No differences in SPID between treatments were observed at 2 and 3 months after patch application. Changes in IENFD on the pain side, from baseline to 1 month after patch application, did not differ between capsaicin and placebo treatment: 1.9 [-0.1 to 3.9] and 0.6 [-1.2 to 2.5] fibers/mm, respectively (P = 0.32). No significant changes in sensory function, sleep quality or psychological factors were associated with capsaicin patch treatment.
  
  
  CONCLUSIONS
  The study did not demonstrate significant differences in pain relief between capsaicin and placebo treatment, although a trend toward pain improvement in capsaicin treated patients was observed 1 month after patch application.
  
  
  BACKGROUND
  Clinicaltrialsregister.eu 2012-001540-22 ClinicalTrials.gov NCT01699854.
authors.affiliation: Multidisciplinary Pain Center 7612, Neuroscience Center, Rigshospitalet, Copenhagen University, Copenhagen, Denmark.
authors.forename: Joakim M
authors.initials: JM
authors.lastname: Bischoff
authors.affiliation: Multidisciplinary Pain Center 7612, Neuroscience Center, Rigshospitalet, Copenhagen University, Copenhagen, Denmark.
authors.forename: Thomas K
authors.initials: TK
authors.lastname: Ringsted
authors.affiliation: Multidisciplinary Pain Center 7612, Neuroscience Center, Rigshospitalet, Copenhagen University, Copenhagen, Denmark.
authors.forename: Marian
authors.initials: M
authors.lastname: Petersen
authors.affiliation: Department of Neurology, University Hospital of Würzburg, Würzburg, Germany.
authors.forename: Claudia
authors.initials: C
authors.lastname: Sommer
authors.affiliation: Department of Neurology, University Hospital of Würzburg, Würzburg, Germany.
authors.forename: Nurcan
authors.initials: N
authors.lastname: Uçeyler
authors.affiliation: Multidisciplinary Pain Center 7612, Neuroscience Center, Rigshospitalet, Copenhagen University, Copenhagen, Denmark.
authors.forename: Mads U
authors.initials: MU
authors.lastname: Werner
mesh_terms: D000328:Adult; D000368:Aged; D002211:Capsaicin / Q000008:administration & dosage* / Q000009:adverse effects; D005260:Female; D006552:Hernia, Inguinal / Q000150:complications*; D006801:Humans; D008297:Male; D008875:Middle Aged; D010146:Pain / Q000209:etiology*; D059408:Pain Management / Q000379:methods; D010147:Pain Measurement; D012307:Risk Factors; D012867:Skin / Q000294:innervation; D011795:Surveys and Questionnaires; D057968:Transdermal Patch
chemical_list: D002211:Capsaicin