gms | German Medical Science

124. Kongress der Deutschen Gesellschaft für Chirurgie

Deutsche Gesellschaft für Chirurgie

01. - 04.05.2007, München

A randomized placebo controlled triple blinded sequential study design to evaluate chronic pain after inguinal hernia repair

Meeting Abstract

  • A. Kurmann - Department of Visceral Surgery, Kantonsspital Luzern, Switzerland
  • corresponding author Ph. Honigmann - Department of Visceral Surgery, Kantonsspital Luzern, Switzerland
  • H. Fischer - Department of Visceral Surgery, Kantonsspital Luzern, Switzerland
  • G. Schüpfer - Department of Anaesthesiology, Kantonsspital Luzern, Switzerland
  • J. Metzger - Department of Visceral Surgery, Kantonsspital Luzern, Switzerland

Deutsche Gesellschaft für Chirurgie. 124. Kongress der Deutschen Gesellschaft für Chirurgie. München, 01.-04.05.2007. Düsseldorf: German Medical Science GMS Publishing House; 2007. Doc07dgch7340

The electronic version of this article is the complete one and can be found online at:

Published: October 1, 2007

© 2007 Kurmann et al.
This is an Open Access article distributed under the terms of the Creative Commons Attribution License ( You are free: to Share – to copy, distribute and transmit the work, provided the original author and source are credited.



Introduction: Inguinal hernia repair is one of the most frequently performed operations in Switzerland. The most common complication postoperatively is development of chronic pain (10-15%) irrespective of the operative technique. We designed a randomized placebo controlled triple blinded trial to investigate the effect of intra-operative infiltration with either Mepivacaine or Placebo. A major problem is an objective evaluation of the intensity of pre- and postoperative pain. The Visual Analogue Scale (VAS) is often used in study designs. However, we believe this method to be very depending on subjective matter of opinion. We are convinced that a more objective and validated tool for the evaluation of pain is the Pain Matcher® which has been used already in the area of gynaecological procedures and dermatology. We use these two methods to record the amount of pain and also to compare the two groups.

Materials and methods: 310 patients scheduled for an inguinal hernia repair are going to be allocated intra-operatively into two groups. Group I patients receive an injection of 20ml Carbostesin® 0.25% at the end of the operation according to a standardised procedure. Group II patients get a 20 ml placebo (0.9% Saline) injection. We use pre-filled identically looking syringes already block randomized and continuously numbered for the blinded injection. The patient, the surgeon and the examinator who performs the postoperative clinical follow-ups are going to be blinded. We included the following procedures for the hernia repair: Lichtenstein, Barwell and TEPP. The primary outcome of the study is the occurrence of developing chronic pain (> 3 months postoperatively).

Results: The study started at 7/2006. We planned 3 interim analyses only unblinding the results if we already reached a significant difference between the groups or if we are going to observe any severe adverse events.

Discussion: Using this sequential study design we adapt the amount of patients needed to show an effect of the intra-operative infiltration. This concept of an adapted sequential study design is new and up to now only used in a few studies. We believe to reduce the number of patients to a minimum needed to show an effect of the treatment with this design. This clear study design also reduces the most common types of bias. We hope to contribute with this study to the most common postoperative complication after hernia repair. Furthermore, we will try to figure out a preoperative high-risk profile of the “chronic pain” patients.