Miniport versus standard ports for laparoscopic cholecystectomy
Abstract
This is a protocol for a Cochrane Review (Intervention). The objectives are as follows:
To assess the benefits and harms of miniport laparoscopic cholecystectomy versus conventional laparoscopic cholecystectomy.
Background
About 10% to 15% of the adult western population have gallstones (Jørgensen 1987; NIH 1992; Muhrbeck 1995; Halldestam 2004). Between 1% and 4% become symptomatic in a year (NIH 1992; Halldestam 2004). More than half a million cholecystectomies are performed per year in the United States alone (NIH 1992). Regional differences exist in the cholecystectomy rates (Mjäland 1998). Laparoscopic cholecystectomy (removal of gallbladder through a key‐hole, also known as port), which was introduced in 1987, is now the preferred method of cholecystectomy (NIH 1992; Fullarton 1994; Bakken 2004; Keus 2006).
In conventional laparoscopic cholecystectomy, four ports (two of 10 mm diameter and two of 5 mm diameter) are used (Alponat 2002; Bisgaard 2002). Recently, use of smaller ports ('miniports' defined as one or more ports smaller than the conventional ports used) have been reported (Alponat 2002; Ainslie 2003). The advantages of using a smaller port for performing laparoscopic cholecystectomy include decreased incisional pain (Bisgaard 2002), lower requirement of parenteral opiate for pain relief (Ainslie 2003), and better cosmesis (Alponat 2002; Bisgaard 2002). However, the safety of using small instruments is a matter of concern. Furthermore, the miniport laparoscopic cholecystectomy increases operating time (Huang 2003). Some randomised clinical trials have reported no difference in the pain scores (Alponat 2002), requirement of analgesia (Alponat 2002), pulmonary functions (Ainslie 2003), hospital stay (Bisgaard 2002; Huang 2003), or return to work (Bisgaard 2002).
We have not been able to identify any systematic review or meta‐analysis comparing miniport laparoscopic cholecystectomy with conventional laparoscopic cholecystectomy.
Objectives
To assess the benefits and harms of miniport laparoscopic cholecystectomy versus conventional laparoscopic cholecystectomy.
Methods
Criteria for considering studies for this review
Types of studies
We will consider for inclusion in the review only randomised clinical trials (irrespective of language, blinding, or publication status).
Quasi‐randomised studies (where the method of allocating participants to a treatment are not strictly random (eg, date of birth, hospital record number, alternation), cohort studies, and case‐control studies will not be included regarding assessment of benefit, but will be included regarding assessment of harm.
Types of participants
Patients undergoing laparoscopic cholecystectomy.
Types of interventions
We will include trials comparing miniport laparoscopic cholecystectomy (defined as one or more ports smaller than the conventional ports used) with conventional laparoscopic cholecystectomy (four port laparoscopic cholecystectomy with two 10 mm ports and two 5 mm ports).
Types of outcome measures
(1) Mortality.
(2) Surgery‐related morbidity (bile duct injury, re‐operations, intra‐abdominal collections, wound infection, infected intra‐abdominal collections).
(3) Conversion to open cholecystectomy.
(4) Conversion to standard laparoscopic cholecystectomy.
(5) Pulmonary functions (however defined by authors).
(6) Pain (however defined by authors) (pain scores at various time points and at different sites ‐ shoulder, abdomen, wound, unclassified; and requirement for analgesia).
(7) Cosmesis (however defined by authors).
(8) Patient satisfaction (however defined by authors).
(9) Operating time.
(10) Hospital stay.
Search methods for identification of studies
We will search The Cochrane Hepato‐Biliary Group Controlled Trials Register (Gluud 2007), the Cochrane Central Register of Controlled Trials (CENTRAL) in The Cochrane Library, MEDLINE, EMBASE, and Science Citation Index Expanded (Royle 2003). We have given the preliminary search strategies in Appendix 1 with the time span for the searches. As the review progresses, we will improve them if necessary.
Data collection and analysis
Trial selection and extraction of data
The authors will not apply any language or publication status restrictions. KG and KS will, independently of each other, identify the trials for inclusion. KG and KS will also list the excluded trials with the reasons for the exclusion. KG and KS will also search the references of the identified trials to identify further relevant trials.
KG and KS will extract independently the data listed below:
(1) Year and language of publication.
(2) Country.
(3) Year of study.
(4) Inclusion and exclusion criteria.
(5) Sample size.
(6) Pressure used for pneumoperitoneum.
(7) Size and number of the ports in each group.
(8) Drain use.
(9) Number of laparoscopic cholecystectomies performed in acute cholecystitis.
(10) Outcomes (mentioned above).
(11) Methodological quality (described below).
(12) Sample size calculation.
(13) Intention‐to‐treat analysis.
The authors will assess the methodological quality of the trials independently, without masking of the trial names. Any unclear or missing information will be sought by contacting the authors of the individual trials. If there is any doubt whether the trials share the same patients ‐ completely or partially (by identifying common authors and centres) ‐ the authors of the trials will be contacted to clarify whether the trial has been duplicated.
We will resolve any differences in opinion through discussion.
Assessment of methodological quality
The authors will follow the instructions given in the Cochrane Handbook for Systematic Reviews of Intervention (Higgins 2006) and the Cochrane Hepato‐Biliary Group Module (Gluud 2007). Due to the risk of overestimation of intervention effects in randomised trials with inadequate methodological quality (Schulz 1995; Moher 1998; Kjaergard 2001), we will look at the influence of methodological quality of the trials on the trial results by evaluating the reported randomisation and follow‐up procedures in each trial. If information is not available in the published trial, we will contact the authors in order to assess the trials correctly. We will assess generation of allocation sequence, allocation concealment, and follow‐up.
Generation of the allocation sequence
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Adequate, if the allocation sequence was generated by a computer or random number table. Drawing of lots, tossing of a coin, shuffling of cards, or throwing dice will be considered as adequate if a person who was not otherwise involved in the recruitment of participants performed the procedure.
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Unclear, if the trial was described as randomised, but the method used for the allocation sequence generation was not described.
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Inadequate, if a system involving dates, names, or admittance numbers were used for the allocation of patients. These studies are known as quasi‐randomised and will be excluded from the review.
Allocation concealment
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Adequate, if the allocation of patients involved a central independent unit, on‐site locked computer, or sealed envelopes.
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Unclear, if the trial was described as randomised, but the method used to conceal the allocation was not described.
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Inadequate, if the allocation sequence was known to the investigators who assigned participants or if the study was quasi‐randomised (such studies will be excluded).
Blinding will not be assessed since we expect that there will be no double‐blind trials. However, we will record whether the outcomes were assessed by a blinded observer.
Follow‐up
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Adequate, if the numbers and reasons for dropouts and withdrawals in all intervention groups were described or if it was specified that there were no dropouts or withdrawals.
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Unclear, if the report gave the impression that there had been no dropouts or withdrawals, but this was not specifically stated.
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Inadequate, if the number or reasons for dropouts and withdrawals were not described.
Statistical methods
We will perform the meta‐analyses according to the recommendations of The Cochrane Collaboration (Higgins 2006) and the Cochrane Hepato‐Biliary Group Module (Gluud 2007). We will use the software package RevMan 4.2 (RevMan 2003). For dichotomous variables, we will calculate the odds ratio with 95% confidence interval. For continuous variables, we will use the weighted mean difference (for outcomes like operating time, hospital stay, etc) and standardised mean difference (for outcomes like pain, cosmesis, etc where different scales can be used). We will use a random‐effects model (DerSimonian 1986) and a fixed‐effect model (DeMets 1987). In case of discrepancy between the two models we will report both results; otherwise we will report only the results from the fixed‐effect model. Heterogeneity will be explored by chi‐squared test with significance set at P value 0.10, and the quantity of heterogeneity will be measured by I2 (Higgins 2002).
We will adopt the 'available case analysis'. In case that there are more than a few drop‐outs, we will also conduct 'worst‐best case analysis' and 'best‐worst case analysis' (Gluud 2007). The analysis will be performed on an intention‐to‐treat basis (Newell 1992). In case we find 'zero‐event' trials for outcomes that are statistically significant without including the 'zero‐event' trials, we will perform a sensitivity analysis with and without empirical continuity correction factors as suggested by Sweeting et al (Sweeting 2004).
Subgroup analysis
We will perform subgroup analyses for:
‐ Elective cholecystectomy.
‐ Emergency cholecystectomy.
‐ Different sizes of ports of mini‐laparoscopic cholecystectomy.
‐ Methodological quality and hence bias risk of the trials.
Bias exploration
We will use a funnel plot to explore bias (Egger 1997; Macaskill 2001). We will perform linear regression approach described by Egger et al to determine the funnel plot asymmetry (Egger 1997).
