Postsurgical pain outcome of vertical and transverse abdominal incision: Design of a randomized controlled equivalence trial [ISRCTN60734227]

Abstract

BackgroundThere are two ways to open the abdominal cavity in elective general surgery: vertically or transversely. Various clinical studies and a meta-analysis have postulated that the transverse approach is superior to other approaches as regards complications. However, in a recent survey it was shown that 90 % of all abdominal incisions in visceral surgery are still vertical incisions. This discrepancy between existing recommendations of clinical trials and clinical practice could be explained by the lack of acceptance of these results due to a number of deficits in the study design and analysis, subsequent low internal validity, and therefore limited external generalisability. The objective of this study is to address the issue from the patient's perspective.MethodsThis is an intraoperatively randomized controlled observer and patient-blinded two-group parallel equivalence trial. The study setting is the Department of General-, Visceral-, Trauma Surgery and Outpatient Clinic of the University of Heidelberg, Medical School. A total of 172 patients of both genders, aged over 18 years who are scheduled for an elective abdominal operation and are eligible for either a transverse or vertical incision. To show equivalence of the two approaches or the superiority of one of them from the perspective of the patient, a primary endpoint is defined: the pain experienced by the patient (VAS 0–100) on day two after surgery and the amount of analgesic required (piritramide [mg/h]). A confidence interval approach will be used for analysis. A global α-Level of 0.05 and a power of 0.8 is guaranteed, resulting in a size of 86 patients for each group. Secondary endpoints are: time interval to open and close the abdomen, early-onset complications (frequency of burst abdomen, postoperative pulmonary complications, and wound infection) and late complications (frequency of incisional hernias). Different outcome variables will be ranked by patients and surgeons to assess the relevance of possible endpoints from the patients' and surgeons' perspective.ConclusionThis is a randomized controlled observer and patient-blinded two-group parallel trial to answer the question if the transverse abdominal incision is equivalent to the vertical one due to the described endpoints.

Ranking of patient and surgeons' perspectives for endpoints in randomized controlled trials—lessons learned from the POVATI trial [ISRCTN 60734227]

“…Because scientific analysis of such ranking procedures is a rather young and challenging area [11], validated tools have not been established yet. The POVATI trial (ISRCTN 60734227) was a randomized, patient-and observer-blinded, monocentric, equivalence clinical study in which patients scheduled for elective primary abdominal incisions were randomized to midline or transverse incision [16,17]. The composite primary endpoint was the total amount of analgesics (piritramide) required in the last 24 h measured 48 h after surgery.…”

“…The study protocol was published in advance to establish transparency of the design and analysis, including the ranking procedure [16]. The protocol was approved by the local ethics committee of the University of Heidelberg and the trial was internationally registered (ISRCTN 60734227).…”

“…The Postsurgical Pain Outcome of Vertical and Transverse Abdominal Incision randomized trial (POVATI) [16] was designed as a patient-and observer-blinded RCT to compare both access types with a composite primary endpoint, i.e., the pain experienced by the patient measured using the visual analogue scale (VAS 0-100) on day 2 after surgery and the amount of analgesic required (use of piritramide in milligram per hour over 24 h). No differences between the incisions were observed for pain, pain medication needed, pulmonary complications, length of hospital stay, and incisional hernias [17].…”

The Study Centre of the German Surgical Society?rationale and current status

“…The protocols are published so that subsequently undetectable changes can be prevented and transparent study conditions achieved [22]. All published results can be reviewed and discrepancies with the initial study protocol have to be discussed.…”

“…When subjective outcomes are to be measured, blinding is a must to reduce observational bias. When the patient and the outcome assessor are blind to the nature of the operation, it is possible for a quasi-double blind design to be achieved, even in surgical trials [13,16,22].…”