The objective of this study is to define the role of laparoscopic treatment in patients with symptomatic diverticulitis. The Sigma-trial is a prospective, multi-center, double-blind, randomized study. Patients with symptomatic diverticulitis are randomized for either open or laparoscopic sigmoid resection. Our hypothesis is that patients undergoing laparoscopic sigmoid resection have fewer complications, less pain and earlier discharge from the hospital.
Primary endpoints of the study are postoperative morbidity and mortality. Minor complications are defined as wound infections, urine tract infections pneumonia, venous thrombosis or other. Major complications consist of anastomotic leakages, postoperative haemorrhage, intra-abdominal abscesses, re-operations and other within the first four postoperative weeks. Data concerning late complications after four weeks are collected at the outpatient clinic six months postoperative (i.e. incisional hernia, ileus or other).
The secondary endpoints are procedure related events such as duration of operation, conversion to open procedure in laparoscopic group, blood-loss during operation, number of re-admissions and re-operations. Furthermore postoperative recovery data are hospital stay (days), type and number of analgesics needed after operation, VAS-painscore, return to fluid and normal diet, postoperative ileus, SF-36 questionnaire (general health) translated and adapted to nationality, recurrence rate after five years.
Power of the study
According to the published literature and own experience at the VU medical centre a difference in morbidity of 23% is found between the open procedure (35%) and the laparoscopic procedure (12%) [19–21]. To demonstrate this difference of 23%, using α = 0.05 and β = 0.2, two groups of 52 patients are required. This means that a total of 104 patients have to be included.
Patients who were admitted for a conservatively treated episode of diverticulitis, who will therefore undergo an elective resection of the sigmoid. The indication for elective resection is in patients < 50 years after one episode of conservatively treated diverticulitis and in patients older than 50 years after two episodes of diverticulitis or in case of progressive abdominal complaints due to strictures caused by a previous episode of diverticulits. Moreover patients with recurrence of bleeding are candidates for inclusion. The diagnosis diverticulitis is confirmed by CT-scan and/or barium enema and coloscopy.
Operation will take place at least after three months of the last attack of diverticulitis.
Exclusion criteria are signs of acute diverticulitis, previous infra umbilical laparotomy or previous colorectal surgery or no informed consent. Presence of a fistula is not considered as exclusion criteria.
Participating surgeons and clinics
Complication rate, duration of operation and morbidity can be a result of the learning curve of the operating surgeon. To prevent surgeon bias, the open and laparoscopic operations have to be performed by surgeons experienced in both techniques. It is reported that after 15 operations, operating time decreases significantly which could be an indication of the end of the learning curve . Therefore it is required that the participating surgeon has performed at least 15 laparoscopic sigmoid resections as well as 15 open sigmoid resections.
Five European academic and non-academic centres will participate in the study: Academisch Medisch Centrum, Amsterdam; Hospital Clinic, Barcelona; Central teaching Hospital, Forde; Waterland Ziekenhuis, Purmerend; and VU medical centre, Amsterdam.
Randomization and blinding
The patient will be informed about the trial at the outpatient clinic. When informed consent is obtained, the patient will be randomised at the outpatient clinic. Randomization is performed by an internet randomization module. Participating surgeons are allowed to login to the secured Sigma-trial website, after filling out the randomization form immediate response with randomization number and type of operation is obtained.
In order to perform a double-blind study, the patient will not be informed which procedure he or she will undergo. Also the ward physician and nurses are not informed about the type of procedure. Patients will be put on the waiting list as indication: 'Sigma-trial', without verifying the type of operation. Postoperative an opaque dressing will be applied to cover the wounds for five days and the surgery details will be kept separate from the patient's notes. When the patient does not agree to participate he or she will undergo the standard procedure in the corresponding department.
Data collection and statistics
Data are partially collected via a secured internet module, which is specially designed for the Sigma-trial, and via datasheets on paper, which are sent to the VU medical centre by mail. Data are collected daily until the day of discharge. Preoperatively, at six weeks and six months postoperatively the SF-36 questionnaire is filled in by the patient.
There will be regular contact between the study coordinators and the participating centres. One research fellow will monitor the data of every included patient. An SPSS-database will be created with all required parameters. Data analysis will be performed in accordance with the intention to treat principle. Groups will be compared using an Independent Samples T-test where appropriate, other wise a Willcoxon or Chi-square tests. Painscores will be analysed using repeated measures analysis.
This study is conducted in accordance with the principles of the Declaration of Helsinki and 'good clinical practice' guidelines. The independent medical ethics committees of the participating hospitals have approved the study protocol. Prior to randomization, written informed consent will be obtained from all patients.