Systematic review and meta-analysis of single-incision versus conventional multiport laparoscopic splenectomy.

BACKGROUND: There is no consensus that single-incision laparoscopic surgery splenectomy (SILS-SP) is on a par with conventional multiport laparoscopic surgery splenectomy (CMLS-SP). AIMS: The aim of this systematic review and meta-analysis was to assess feasibility and safety of SILS-SP when compared with CMLS-SP.
MATERIALS AND METHODS: Eligible articles were identified by searching several databases including PubMed, EMBASE, CNKI (China) and the Cochrane Library, up until February 2016. Studies were reviewed independently and rated by Newcastle-Ottawa Quality Assessment Scale. Evaluated outcomes were complications, operative time, post-operative hospital stay, blood loss, starting diet, post-operative pain scores, conversion and analgesic requirements.
RESULTS: Ten retrospective studies met the eligibility criteria. Overall, there was no significant difference between SILS-SP and CMLS-SP in complications, operative time, post-operative hospital stay, blood loss, starting diet, post-operative pain scores, conversion and analgesic requirements.
CONCLUSIONS: SILS-SP is feasible and safe in certain patients, with no obvious advantages over CMLS-SP. Therefore, it may be considered an alternative to CMLS-SP. We await high-quality, double-blind RCTs. These should include clear statements on standard scores of post-operative pain and cosmetic results, longer follow-up assessment and cost-benefit analysis.

INTRODUCTION

Conventional multiport laparoscopic surgery splenectomy (CMLS-SP) has gained acceptance among surgeons because of several advantages such as improving patient morbidity, reducing length of stay in hospital, reducing perioperative pain and providing enhanced cosmesis.[1] With superior patient outcomes than open splenectomy, CMLS-SP has become the gold standard procedure for spleen removal;[1] however, the disadvantage of this procedure is that multiple incisions are needed.

During the past two decades, to minimise operative invasiveness and improve post-operative cosmetic results, minimally invasive surgery has continued to evolve and several methods have been described including orifice translumenal endoscopic surgery, reduced port laparoscopic surgery and single-port incision surgery, which also applying in splenectomy.[234] Single-incision laparoscopic surgery splenectomy (SILS-SP) was first described by Barbaros and Dinççagin 2009[5] but was not widespread up to date, one of the main concerns has always been its safety. To date, ten studies compared SILS-SP to CMLS-SP have been published but were limited by their sample sizes and were not individually powered to detect small differences in outcomes.[467891011121314] In addition, the feasibility and safety of SILS-SP were not well established.

The aim of this systematic review was to examine currently available evidence on the feasibility and safety of SILH and to compare short-term outcomes after SILS-SP and CMLS-SP as reported in retrospective studies.

MATERIALS AND METHODS

Literature search

A systematic literature search was performed using PubMed, EMBASE, CNKI (China) and the Cochrane Library to search for studies comparing SILS-SP to CMLS-SP (to February 2016). The following medical subject heading (MeSH) terms and words were used for the search, in all possible combinations: ‘Laparoendoscopic single-site surgery’, ‘single-incision laparoscopic surgery’, ‘SILS’, ‘single-port surgery’, ‘SPS’, ‘single-port access’, SPA’, ‘transumbilical endoscopic surgery’, ‘TUES’, ‘laparoendoscopic single-site’, ‘LSS’, ‘transumbilical single-port’, ‘TUSP’, ‘single-incision multiport’, splenectomy’ and ‘lienectomy’, without any language restriction. A second-level search that included a manual search of the reference lists of all the relevant studies, systematic reviews and previous meta-analyses to identify potential eligible studies.

Inclusion and exclusion criteria

(1) This review included only retrospective studies that compared SILS-SP to CMLS-SP. SILS-SP can be performed using laparoscopic or endoscopic instruments, in which case, it is referred to as laparoendoscopic single-site surgery or single-incision endoscopic surgery; (2) written in English and Chinese; (3) only the full-text available; (4) all included studies had to report at least one of the following outcome measures: Complications, operative time, post-operative hospital stay, blood loss, starting diet, post-operative pain scores, analgesia requirements, conversion and cosmetic scores; (5) if two studies from the same institution were identified, the most recent or the most informative was selected, unless they were reports from different periods or if the data of overlapping patients could be subtracted.

Outcome measures

Outcome variables were considered suitable for analysis if they met the following criteria: (1) Continuous outcomes were reported as means and standard deviations; (2) identical variables reported by a minimum of two studies; at last, eight outcome variables were considered the most suitable for analysis: Operative time (min), post-operative hospital stay (day), <span class="Disease">blood loss (ml), starting diet (day), complications (n), conversion (n), analgesic requirements and post-operative <span class="Disease">pain scores.

Data extraction and quality assessment

Data were extracted from each study by two independent reviewers (Shike Wu and Hao Lai):First author, study design, country, Species">patients, number of patients, MILH technique, SILH device, spleen size (g), duration of follow-up, quality score and inclusion criteria. Extracted tables were exchanged when the work was finished, and if necessary, agreement was achieved through discussion. If the required data were not available in the published study, the authors were contacted and asked to supply the information.

All of the studies included in the meta-analysis were retrospective cohort studies. In accordance with the Oxford Centre for Evidence-Based Medicine Levels of Evidence,[15] the Newcastle–Ottawa Quality Assessment Scale was used to assess the quality of cohort studies.[16] This scale contains eight items categorised into three dimensions – selection, comparability and outcome. A maximum of one star can be awarded for each item, and the item of comparability allows two stars. Total scores range from 0 <span class="Species">to 9, with a higher score indicating a higher quality level. Studies with Newcastle–Ottawa scores ≥6 were considered to be of high quality.

Statistical analysis

Data were analysed using the software Stata 12.0 (Stata Corp, College Station, TX, USA). For continuous variables, we calculated weighted mean diffe<span class="Gene">rence (WMD) with 95% confidence intervals (95% CIs). For dichotomous variables, we used odds ratios (ORs). We used the Q-based Chi-square test and the I2 statistic to assess heterogeneity between studies, with a P < 0.05 representing statistical significance. Publication bias was evaluated by a funnel plot. Egger's test was used to assess the funnel plot for significant asymmetry, an indication of possible publication or other bias. Sensitivity and subgroup analyses were used to explore potential causes of heterogeneity.

RESULTS

Of 142 records retrieved from the database search, none was identified through other sources. Figure 1 depicts a PRISMA flow chart for study inclusion and exclusion. After removing duplicate results, 132 records remained. Of these, eleven studies were selected for full-text examination.[3467891011121314] One of them was excluded due to raw data could not be extracted in the appropriate format and failed to be obtained from the authors or other published results.[3] At last, ten studies were suitable for the meta-analysis.[467891011121314]

Figure 1

Flow diagram of the literature search

Characteristics of included studies

Tables 1 and 2 list the surgical instruments and the main characteristics of the ten studies included in this analysis. Of 332 Species">patients included, 146 underwent SILS-SP and 186 CMLS-SP. The articles included in the quantitative synthesis were published between 2013 and 2015. One study included three group dates, and the available outcomes were extracted to allow pooled analysis.[4] The SILS-SP approaches used were diverse including QuadPort™ multichannel trocar,[10] three trocar inserted through the single-site incision,[46814] multiport device,[4] X-CONE single-port,[13] Glove port,[12] SILS™ port of Covidien, Mansfield, MA, USA[11] Gelpoint device,[9] handmade single-port and OCTO port.[7] The methodological quality of included studies was relatively high, with a score of six or seven stars.

Table 1

Characteristics of the studies included in the meta-analysis

Table 2

Surgical instruments used in the studies included in the meta-analysis

Outcome measurements

The meta-analysis of the outcome investigated overall complication in eight studies.[46789101112] The most common seen complication was haemorrhage, and one patient died due to this on post-operative day 7,[9] and one patient received nephrectomy concomitantly died for post-operative bleeding in CMLS-SP group.[12] The raw incidence of global complication was similar for both treatment groups, the OR was 0.97 (95% CI: 0.47–2.00; P = 0.934) [Figure 2a]. No heterogeneity was found (I2 = 0.0% and P = 0.976).

Figure 2

(a) Forest plot of the comparison of complications between single-incision laparoscopic surgery splenectomy and conventional multiport laparoscopic surgery splenectomy. (b) Forest plot of the comparison of conversions between single-incision laparoscopic surgery splenectomy and conventional multiport laparoscopic surgery splenectomy

All studies evaluated conversions,[467891011121314] and 17 <span class="Species">patients from six studies required conversions.[4910111214] Without heterogeneity across trials (I2 = 7.5% and P= 0.368). The results showed conversions were the same in both treatment subgroups (OR = 1.81, 95% CI: 0.71–4.63, P = 0.212) [Figure 2b].

All trials mentioned results about operative time,[467891011121314] and in eight trials, this results were present as mean and standard deviation,[478911121314] heterogeneity was found (I2 = 89.0% and P= 0.00), there was no significant diffe<span class="Gene">rence between two groups (WMD = 13.17, 95% CI: 9.43–35.76, P = 0.253) [Figure 3a].

Figure 3

(a) Forest plot of the comparison of operative time between single-incision laparoscopic surgery splenectomy and conventional multiport laparoscopic surgery splenectomy. (b) Forest plot of the comparison of post-operative hospital stay between single-incision laparoscopic surgery splenectomy and conventional multiport laparoscopic surgery splenectomy

Nine trials reported results about post-operative hospital stay,[4678910111214] two studies were excluded for not reporting as means and standard deviation.[610] There was no significant diffe<span class="Gene">rence between two groups (WMD = −0.08 95% CI: −0.47–0.31, P = 0.686) [Figure 3b], no heterogeneity was found (I2 = 0.0% and P= 0.555).

Mean volume of <span class="Disease">blood loss was reported in seven studies,[78911121314] heterogeneity was found (I2 = 77.4% and P= 0.00), and thus the random-effects model with MD was used. The results showed no diffe<span class="Gene">rence between two groups (WMD = −1.57, 95% CI: −25.41–22.27, P = 0.897) [Figure 4a].

Figure 4

(a) Forest plot of the comparison of blood loss between single-incision laparoscopic surgery splenectomy and conventional multiport laparoscopic surgery splenectomy. (b) Forest plot of the comparison of starting diet between single-incision laparoscopic surgery splenectomy and conventional multiport laparoscopic surgery splenectomy

(a) Forest plot of the comparison of <span class="Disease">blood loss between single-incision laparoscopic surgery splenectomy and conventional multiport laparoscopic surgery splenectomy. (b) Forest plot of the comparison of starting diet between single-incision laparoscopic surgery splenectomy and conventional multiport laparoscopic surgery splenectomy

Three trials reported results about starting diet,[7814] heterogeneity was found (I2 = 54.9% and P= 0.109). The results showed no diffe<span class="Gene">rence between two groups (WMD = 0.16, 95% CI: −0.35–0.67, P = 0.534) [Figure 4b].

Analgesic requirements were evaluated in three studies.[479] There was no significant heterogeneity among the studies in total doses of analgesics used (I2 =0.0%, P= 0.522), the results showed no significant diffe<span class="Gene">rence in the total doses of analgesics used between the groups (WMD = −1.01, 95% CI: −7.58–5.56, P = 0.763) [Figure 5a].

Figure 5

(a) Forest plot of the comparison of analgesic requirements between single-incision laparoscopic surgery splenectomy and conventional multiport laparoscopic surgery splenectomy. (b) Forest plot of the comparison of post-operative pain scores between single-incision laparoscopic surgery splenectomy and conventional multiport laparoscopic surgery splenectomy

(a) Forest plot of the comparison of analgesic requirements between single-incision laparoscopic surgery splenectomy and conventional multiport laparoscopic surgery splenectomy. (b) Forest plot of the comparison of post-operative <span class="Disease">pain scores between single-incision laparoscopic surgery splenectomy and conventional multiport laparoscopic surgery splenectomy

Five studies described the post-operative pain scores,[6781114] four studies were evaluated by means of visual analogue scales (VAS)[681114] and one was numeric pain rating scale, Bayraktar et al. and Shao only displayed the results of pain scores. The pooled analysis of two studies shows no difference between two groups on the first post-operative day (WMD = −1.29, 95% CI: −3.06–0.47, P = 0.151), but with significant heterogeneity (I2 =94.7%, P= 0.00)[811] [Figure 5b]. Then, we performed a subgroup by method of assessment of pain scores; we did not find any different between two groups (P = 0.053).

Sensitivity analysis

The inclusion criteria of this meta-analysis were subjected to sensitivity analysis to determine whether modification of the inclusion criteria of the meta-analysis affected the results [Figure 6a]. A single study involved in the meta-analysis was deleted each time to reflect the influence of each individual data set on the pooled ORs. The corresponding pooled ORs were essentially unaltered (data not shown), indicating that our results were statistically sound.

Figure 6

(a) Sensitivity analysis for complications. (b) Funnel plot of complications

Risk of publication bias

A funnel plot of the studies included in our outcome of complications was created to explore publication bias, all studies lie inside the 95% CIs, with an even distribution around the vertical, indicating no evidence of publication bias [Figure 6b].

DISCUSSION

As laparoscopic skills improve and technologies advance, SILS was suggested as an alternative technology to traditional laparoscopic for reducing post-operative <span class="Disease">pain and improving cosmetic results[17] and was applied in a variety of general surgery cases; the most common procedures are single-port laparoscopic cholecystectomies, colectomies and appendectomies.[18] Many studies have evaluated the feasibility and safety of this type of surgery including reviews and meta-analysis.[192021] However, limited date was applied in <span class="Chemical">SILS-SP.

Although SILS-SP is successfully performed for certain patients, unfortunately, most publications regarding SILS-SP are case reports with small series.[34678910111213142223] Inconsistent results even presented such as operative time.[49] Several reviews have evaluated the feasibility and safety of SILS-SP,[1242526] but the latest one involved literature searches only up to June 2012,[26] leading to the selection of a series of case report. Our meta-analysis, using the standardised comparisons, provides the most up-to-date compilation of studies including ten studies. It should be the most comprehensive analysis about this topic, which provides a robust tool to investigate inconsistent results. Complication occurring in splenectomy mainly secondary to bleeding or injury to the pancreatic tail or are pulmonary in origin, and the safety and feasibility of SILS-SP could be evaluated by complication rate. The most common complication in SILS-SP group was haemorrhage; it did not apparently higher than CMLS-SP group (5 SILS-SP vs. 3 CMLS-SP). Avoidance of port placement-related injuries may be potential advantage of the SILS-SP[10] although the frequency of haemorrhagic complications related to laparoscopic port sites is extremely low.[2728] In general, SILS-SP is more technologically difficult and results in a longer operative time, five studies supported this trend[78111213] but others did not.[4691014] This might have been because SILS-SP procedure in those studies was performed by a single surgeon, whereas CMLS-SP procedures were performed by different surgeons, a potential bias lead to the inconsistent result. Pooling these trials did not reveal an overall significantly longer operating time for SILS-SP, which has important implications for both patients and health-care providers because of longer surgical procedures mean that patients are exposed to protracted anaesthesia that can increase not only the direct cost of the procedure but also the morbidity and even mortality rates.

Technological difficulty may also be associated with conversion. In SILS-SP, crowding over the access port or access site can led to the interference of surgical instruments,[35] hindering the surgical process. However, conversion to open surgery was found to be similar for both techniques. This may be because the study design in involved trails was non-random, patients in most studies were carefully selected before being offered SILS-SP, complicated cases, such as patients who underwent combined procedures for extra-spleen conditions with multiple-incision laparoscopic surgery splenectomy or SLIS-SP were excluded; some instruments such as Ligasure device and vascular stapler were applied to reduce technology difficulty,[4678910] additional trocar was even applied in SILS-SP procedure, which might decrease the conversion rate.[46] Further studies including complicated cases are required to better assess all aspects of the SILS-SP procedure.

Hospital stay favour SILS-SP groups excepted Choi et al. and Fan et al. subgroups,[78] but the pooled estimates showed no significant difference between these two technologies. Length of hospital stay was partly associated with type of complications, and the complication occurring in involved studies were not uniform. For example, for the Choi et al. subgroup,[7] haemorrhage presented in SILS-SP procedure, whereas in CMLS-SP procedure was refractory ITP and complicated fluid collection in the splenic fossa which might increase the length of hospital stay.

Blood loss estimated is another endpoint which evaluated safety and feasibility of SILS-SP. In SILS-SP, surgeon was required to be facile in the dissection of complex tissue planes and well versed with the control of blood vessels, but loss of triangulation and decreased range of motion to manoeuvre instruments might increase technology difficulty of SILS-SP, which resulted in more blood loss. However, not all results supported this trend,[91214] possibly due to the learning curve in surgeons were different and some instruments (Ligasure device and vascular stapler) were applied to reduce technology difficulty intraoperatively, and the pool estimated showed that there was no significant different between SILS-SP and CMLS-SP.

The use of an SILS minimises abdominal trauma and has the theoretical advantages of less pain, only three studies reported as means and standard deviation with different methods of assessment of pain scores,[7811] only two studies evaluated post-operative pain scores with VAS, and the pooled analysis showed no difference between two groups. Analgesic requirements were found to be similar for both techniques.[479] Considering the value of post-operative pain scores in SILS, future studies with larger sample sizes are also needed to evaluate the post-operative pain scores for SILS-SP fully.

As minimally invasive surgery has continued to evolve, <span class="Species">patients have obtained better cosmesis and satisfaction, as fewer incisions are made during SILS.[29] Only two studies evaluated cosmetic results,[413] and <span class="Gene">Ren et al. showed better cosmetic score (P < 0.01), however with different method of evaluating cosmetic, no cosmetic analysis was conducted in this review.

Our meta-analysis included several limitations. First, the advantage of SILS-SP should be mainly demonstrated by post-operative pain scores and cosmetic outcome; however, data were not enough to show its advantage. Moreover, no cost analysis was conducted in this review for only one study measured cost outcome.[8] Second, the studies involved in our meta-analysis were limit (ten retrospective studies), and sample size was small (146 vs. 186). In addition, blinding assessment of outcomes was rarely performed. Third, SILS-SP was performed only for uncomplicated patients. Some complicated case such as patients who underwent combined procedures for extra-spleen conditions were excluded, leading to potential bias for this analysis. Fourth, the SILS approaches used were not uniform. Although the use of several single-port systems may enhance the technical feasibility of SILS-SP, few studies have compared the benefits of the different single-port systems. Additional prospective studies are necessary to investigate the benefits of the different single-port systems used in SILS-SP.

CONCLUSIONS

SILS-SP is feasible and safe in certain patients, with no obvious advantages over CMLS-SP. Therefore, it may be considered an alternative to CMLS-SP. We await high-quality, double-blind RCTs. These should include clear statements on standard scores of post-operative pain and cosmetic results, longer follow-up assessment and cost–benefit analysis.

Financial support and sponsorship

Supported by BaGui Scholars Program Foundation. The contract of Guangxi scientific research and technology development project15104003-1-9.

Conflicts of interest

There are no conflicts of interest.