|Is smaller necessarily better? A systematic review comparing the effects of minilaparoscopic and conventional laparoscopic cholecystectomy on patient outcomes
|McCloy R, Randall D, Schug SA, Kehlet H, Simanski C, Bonnet F, Camu F, Fischer B, Joshi G, Rawal N, Neugebauer EA
This review concluded that the advantages of mini-laparoscopic cholecystectomy compared to conventional laparoscopic cholecystectomy were limited, based on the available data. These conclusions were based on analyses of a subset of small trials of variable quality, and this should be borne in mind when assessing their reliability.
To evaluate the importance of total size of trocar incision in improving surgical outcomes in adult laparoscopic cholecystectomy.
MEDLINE and EMBASE were searched from 1966 to October 2005. Search terms not reported. Only studies reported in English were eligible for inclusion.
Randomised controlled trials (RCTs) that compared mini-laparoscopic cholecystectomy (total size of trocar incision less than 25mm) with conventional laparoscopic cholecystectomy (total size of trocar incision 25mm or more) were eligible for inclusion. Total size of trocar incision was defined as the numerical sum of the lengths of all incisions. Trials were required to report pain using a visual analogue scale or numerical rating scale.
Included trials had total trocar incisions ranging from 14 to 24mm in the mini-laparoscopic groups and from 25 to 32mm in the conventional laparoscopic groups. A range of different postoperative analgesic regimes were employed, with opioids alone or in combination being the most common. In addition to pain, the following outcomes were assessed: use of analgesia, operating time, conversion to conventional laparoscopic or open cholecystectomy, length of hospital stay, cosmetic result, return to normal activity and adverse events.
The authors did not state how the papers were selected for the review, or how many reviewers performed the selection.
Assessment of study quality
Studies were graded from A to D for allocation concealment depending on whether it was adequate, unclear, inadequate or absent. They were also assessed using the Jadad scale which awarded up to 5 points based on the criteria of randomisation, blinding and treatment of withdrawals and drop-outs. Statistical analyses and patient follow-up were also evaluated to determine how closely they complied with CONSORT (Consolidated Standards of Reporting Trials) standards. A level of evidence between 1 and 4 was then determined on the basis of all assessments.
The authors did not state how many reviewers performed the validity assessment.
Means and standard deviations or standard errors were extracted to permit the calculation of between-group differences for each outcome.
The authors did not state how the data were extracted, or how many reviewers performed the extraction.
Methods of synthesis
Weighted mean differences (WMD) with 95% confidence intervals (CI) were calculated for continuous data and odds ratios (OR) with 95% confidence intervals for dichotomous data. Statistical heterogeneity was assessed using a Χ2 test, and a random-effects model was employed where this was found to be significant; otherwise a fixed-effect model was used. Qualitative analyses assessed the number of studies showing a statistically significant between-group difference for an outcome.
Results of the review
Thirteen RCTs (n=968 patients) were included in the review. Sample sizes ranged from 21 to 200. Only six trials scored 3 or more points on the Jadad scale, while six trials also had adequate allocation concealment. Only six trials were included in the meta-analyses of continuous data due to inadequate reporting of means, standard deviations or standard errors in the remaining trials.
No meta-analysis for the primary outcome of patient-reported pain was possible; seven RCTs reported significantly lower postoperative pain in the mini-laparoscopic groups than in the conventional groups, the remaining six trials found no significant differences between groups. Eight trials used strong opioids alone or in combination with other analgesics for postoperative analgesia; meta-analysis of four RCTs revealed no difference between the groups in analgesia requirement.
There were no statistically significant differences in operating time between the groups (six RCTs). Incidence of conversion to open cholecystectomy was significantly higher in the mini-laparoscopic groups (OR 4.71, 95% CI 2.67 to 8.31; 12 RCTs). A substantial number of patients in the mini-laparoscopic groups also underwent full (5.8%) or partial (6.6%) conversion to conventional laparoscopy. Length of hospital stay was significantly shorter in the mini-laparoscopic studies (WMD -0.51 days, 95% CI -0.87 to -0.15; two RCTs). Of the seven trials that assessed cosmetic result, five reported significantly better patient satisfaction in the mini-laparoscopic groups. There were no differences in return to normal activity in any of the six trials that assessed it, or in adverse events where assessed.
Reducing the size of trocar incision resulted in some limited improvement in surgical outcomes after laparoscopic cholecystectomy. However it carried a higher risk of conversion to conventional laparoscopic cholecystectomy or open cholecystectomy.
The review question and the inclusion criteria were clear. The authors searched two relevant databases, but the failure to search for unpublished studies and the restriction to studies reported in English may have led to the introduction of publication or language biases, as well as the omission of some relevant studies. The authors did not report using methods designed to reduce bias and error at any stage of the review process. A validity assessment using appropriate criteria was carried out, but it was not subsequently used to inform the synthesis. The decision to use meta-analysis appeared reasonable, although the use of heterogeneity to determine the use of fixed-effect or random-effects models may not have been appropriate. The quality of the included trials was generally low, and the authors were unable to carry out statistical pooling for the primary review outcome. The authors' conclusions reflected the available data and they acknowledged the impact of limitations in the review process. However, the analyses were based on a subset of small trials of variable quality and this should be borne in mind when assessing the reliability of the conclusions.
Implications of the review for practice and research
Practice: The authors did not state any implications for practice.
Research: The authors stated that further large well-conducted and well-reported RCTs are required to determine whether mini-laparoscopic cholecystectomy offers substantial clinically relevant benefits over conventional laparoscopic cholecystectomy.
All authors are members or associates of the PROSPECT working group which is supported by Pfizer Inc.
McCloy R, Randall D, Schug SA, Kehlet H, Simanski C, Bonnet F, Camu F, Fischer B, Joshi G, Rawal N, Neugebauer EA. Is smaller necessarily better? A systematic review comparing the effects of minilaparoscopic and conventional laparoscopic cholecystectomy on patient outcomes Surgical Endoscopy 2008; 22(12): 2541-2553
Subject indexing assigned by NLM
Analgesics /therapeutic use; Cholecystectomy, Laparoscopic /methods /statistics & numerical data; Esthetics; Humans; Intraoperative Period /statistics & numerical data; Laparotomy /utilization; Length of Stay /statistics & numerical data; Pain Measurement; Pain, Postoperative /drug therapy /epidemiology /prevention & control; Patient Satisfaction; Postoperative Nausea and Vomiting /epidemiology; Randomized Controlled Trials as Topic /statistics & numerical data; Treatment Outcome
Date bibliographic record published
Date abstract record published
This is a critical abstract of a systematic review that meets the criteria for inclusion on DARE. Each critical abstract contains a brief summary of the review methods, results and conclusions followed by a detailed critical assessment on the reliability of the review and the conclusions drawn.