doi:10.1111/codi.13026
Meta-analysis
Postoperative outcomes following mechanical bowel preparation before proctectomy: a meta-analysis D. E. Courtney, M. E. Kelly, J. P. Burke and D. C. Winter Centre for Colorectal Disease, St Vincent’s University Hospital, Dublin, Ireland Received 8 October 2014; accepted 14 March 2015; Accepted Article online 11 June 2015
Abstract Aim Previous meta-analyses of mechanical bowel preparation (MBP) before colorectal surgery have grouped colon and rectal resection together. An increased postoperative morbidity has been suggested in the absence of MBP following proctectomy. The current study used meta-analytical techniques to evaluate the comparative outcome of patients who received MBP prior to proctectomy. Method A comprehensive search was performed for published studies examining the effect of MBP before proctectomy on patient outcome. Random effects methods were used to combine data. Results Eleven studies including 1258 patients were identified. There was no significant difference in overall
Introduction Mechanical bowel preparation (MBP) before colorectal resection is questionable and controversial in the modern perioperative care of colorectal patients [1,2]. While early analyses suggested a higher rate of anastomotic leakage following MBP [3,4], more recent studies of larger patient cohorts have refuted this, but they still suggest MBP is associated with a higher rate of surgical site infection [1]. Although there is considerable consensus regarding the abandonment of MBP in elective colorectal surgery, many surgeons are hesitant in eliminating its use before proctectomy [5,6]. To date, meta-analyses on this subject have grouped colonic and rectal resection, but a recent randomized controlled trial has suggested an improved outcome following MBP before proctectomy [7]. As a pelvic anastomosis is an independent risk factor for anastomotic leakage [8], most colorectal surgeons still use MBP Correspondence to: Danielle E Courtney, Department of Surgery, St Vincent’s University Hospital, Elm Park, Dublin 4, Ireland. E-mail: [email protected]
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morbidity (OR 1.062, 95% CI 0.584–1.933, P = 0.844), anastomotic leakage (OR 1.144, 95% CI 0.767–1.708, P = 0.509), surgical site infection (OR 0.946, 95% CI 0.549–1.498, P = 0.812) or mortality (OR 1.377, 95% CI 0.549–3.455, P = 0.495) between those who did not and those who did receive MBP prior to proctectomy. Conclusion The current study did not demonstrate a beneficial effect of MBP prior to proctectomy, but the data were limited. Decision-making as to its use should be made on a case-by-case basis. Keywords Rectal surgery, surgical outcomes, surgical morbidity, anastomotic leak, mechanical bowel preparation
before rectal cancer surgery [9] in the hope of reducing the incidence and severity of this potentially fatal complication [10,11]. A consensus must be reached from the published literature that focuses on the efficacy and safety of omitting MBP before proctectomy before this practice can be advocated. To address this, we performed a meta-analysis of all published data examining the omission of MBP before proctectomy. The aim of this study was to assess the comparative incidence of anastomotic leakage, pelvic abscess, overall morbidity and inpatient mortality in patients having and not having MBP.
Method Literature search and study selection
A systematic search of the Pubmed and Embase databases was performed for all papers published relating to MBP in the context of rectal resection and its association with postoperative morbidity and mortality. We used the following search algorithm: (rectal OR rectum
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OR proctectomy) AND (resection OR surgery) AND (bowel) AND (cleansing OR preparation). The abstracts of the American Society of Colon and Rectal Surgeons, the Association of Coloproctology of Great Britain and Ireland, the European Society of Coloproctology and the Tripartite Meetings from 2000 to 2013 were screened for relevant (Table 1). We also searched the Cochrane Central Register of Controlled Trials for articles comparing outcomes after proctectomy in those who received MBP and those who did not. The most recent search was performed on 2 January 2015. Two authors (DC and MK) independently performed the searches and reviewed all identified publications and abstracts for inclusion. The full texts of potentially eligible trials were obtained. The reference lists of retrieved papers were further reviewed for additional eligible papers. Discrepancies were identified and resolved by discussion. There were no language restrictions. Individual manuscript quality/risk of bias was also determined by two independent assessors (DC and MK). For nonrandomized studies, the quality of studies was evaluated using the Newcastle–Ottawa Scale [12] which examines three items – patient selection, comparability of the two study groups and assessment of exposure (maximum score 9). For randomized controlled trials, the quality of studies was evaluated using the Jadad scoring system [13] which examines three items – randomization, blinding and withdrawals/dropouts (maximum score 5). Eligibility criteria
To be included, publications were required to compare the postoperative clinical outcomes of patients undergoing rectal resection who were given MBP preoperatively with those who were not. The primary outcome of the study was to assess the incidence of anastomotic leakage in patients undergoing proctectomy with or without preoperative MBP. The secondary outcomes were morbidity, surgical site infection, pelvic abscess formation and mortality. Studies that did not provide data on rectal resections exclusively were excluded. Data extraction and outcomes
Data from the identified studies were extracted independently by two authors (DC and MK) and confirmed by both. The following individual data regarding each eligible trial were extracted using standardized extraction forms: general data (author’s name, study design, year of publication, enrolment interval); characteristics of patients (number, mean age); main features of interventions (type of MBP) and clinical outcome (mortality,
Outcomes after mechanical bowel preparation before proctectomy
morbidity, anastomotic leakage, surgical site infection and abdominopelvic abscess). When data were unclear or incomplete, the corresponding author was contacted to clarify data extraction. Statistical analysis
All pooled outcome measures were determined using a random effects model as described by DerSimonian and Laird [14] and the odds ratio was estimated with its variance and 95% CI. The random effects analysis weighted the natural logarithm of each study’s OR by the inverse of its variance plus an estimate of the between-study variance in the presence of betweenstudy heterogeneity. As previously described, heterogeneity between ORs for the same outcome between different studies was assessed [15]. This was through the use of the I2 inconsistency test and the chi-squared based Cochran’s Q statistic test in which P < 0.05 is taken to indicate the presence of significant heterogeneity. Analyses were conducted using COMPREHENSIVE META-ANALYSIS version 2 (Biostat Inc., Englewood, New Jersey, USA).
Results Eligible studies
Of the 785 publications identified by the initial search, 53 full text articles were reviewed for eligibility. 732 publications were excluded after screening their title and abstract. A further 42 published articles were not included on the basis that they did not contain data on rectal operations exclusively (n = 29), did not compare the role of preoperative use of MBP (n = 1), they were meta-analyses (n = 8) or they were not relevant (n = 4). Eleven publications were thus included in the final analysis for anastomotic leakage rate, with a total of 1258 patients. Four studies with a total of 840 patients had extractable data regarding postoperative morbidity and surgical site infection rates, while three studies with a total of 740 patients had extractable data regarding pelvic abscess formation and mortality rates (Fig. 1). Primary outcome
Anastomotic leakage Eleven studies (n = 1258) compared the rate of anastomotic leakage with and without MBP prior to rectal surgery. Table 1 outlines patient demographics and the type of MBP used. No significant difference was observed in the rate of anastomotic leakage between
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863
864 NA
50 21 29 Laxative + enema + mannitol
N 1
2
75 39 36 Picolax
Multicentre Number of centres Number of surgeons Patients n (total) n (MBP) n (no MBP) Preparation type
62 50 NA 61 NA
23 9 14 PEG-ELS
NA
Y 2
3 (Jadad score) Finland
2000 RCT 2 years
Miettinen [18]
-
44 27 17 -
NA
Y 21
4 (Jadad score) Sweden
2006 RCT –
Jung [19]
63 100 42 87 NA
113 61 52 X-PREP sarget
1
N 1
France
7 (NO score)
2007 Retrospective 5 years
Bretagnol [20]
65 69 NA NA NA
27 10 17 Sodium phosphate or PEG
NA
N 1
3 (Jadad score) Argentina
2008 RCT 19 months
Leiro [21]
-
73 40 33 Phosphosoda
2
Cannot assess United Kingdom N 1
2008 Retrospective –
Evans [22]
-
126 7 119 Picolax
1
United Kingdom N 1
Cannot assess
2008 Retrospective –
Mahadavan [23]
MBP, mechanical bowel preparation; N, no; Y, yes; NA, not assessed; RCT, randomized controlled trial; NO, Newcastle–Ottawa score.
50 46 NA NA NA
N 1
Ireland
Country
66 89 NA 86 NA
3 (Jadad score) Brazil
4 (Jadad score)
Mean age Malignancy (%) Radiotherapy (%) Stapled (%) Stoma end (%)
1994 RCT 15 months
1994 RCT 4 years
Santos [17]
Year Study design Enrolment interval Paper quality
Burke [16]
Study
Table 1 Study characteristics
449 236 213 PEG + bisacodyl or sodium phosphate NA 7 6 7 6
NA
Y 13
3 (Jadad score) Netherlands
2010 RCT 71 months
Van’t Sant [2]
63 100 NA 54 82
178 89 89 X-PREP sarget
NA
Y 8
4 (Jadad score) France
2010 RCT 16 months
Bretagnol [7]
67 97 NA NA NA
100 50 50 PEG
NA
N 1
8 (NO score) Korea
2014 Retrospective 24 months
Kim [24]
Outcomes after mechanical bowel preparation before proctectomy D. E. Courtney et al.
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Outcomes after mechanical bowel preparation before proctectomy
Records identified through database searching (n = 786) Pubmed (780) Cochrane (3) Embase (0) Grey Lit (3)
Records after duplicates removed (n = 785)
Figure 1 The Preferred Reporting Items for Systematic Reviews and MetaAnalyses (PRISMA) flow diagram. Grey Lit, grey literature review: defined as ‘that which is produced on all levels of government, academics, business and industry in print and electronic formats, but which is not controlled by commercial publishers’ (The 4th International Conference on Grey Literature, 1999). MBP, mechanical bowel preparation.
Full-text articles assessed for eligibillity (n = 53)
Studies included in meta-analysis (n = 11)
those receiving and those not receiving MBP preoperatively (8.7% vs 10.3%, MBP vs no MBP; OR 1.144, 95% CI 0.767–1.708, P = 0.509) (Fig. 2). Secondary outcomes
Articles excluded by title & abstract (n = 732) -Review article (71) -Retracted articles (1) -About endoscopy (116) -Not about MBP (249) -Comparison of MBPs (38) -Not about proctecomy (257)
Full text articles excluded (n = 42) -Not exclusively rectal (29) -No comparison made (1) -Meta-analyses (8) -Not relevant (4) Total n = 1 258 patients
trend towards increased abscess formation postoperatively in those not receiving MBP, it was, however, not statistically significant (2.8% vs 5.1%, MBP vs no MBP; OR 1.720, 95% CI 0.527–5.615, P = 0.369) (Table 2, Fig. 4b).
Morbidity
Mortality
Four studies (n = 840) compared the rate of overall postoperative morbidity in those who underwent rectal resection with or without preoperative MBP. No significant difference was observed between those receiving and those not receiving MBP preoperatively in the rate of postoperative morbidity (42.7% vs 43.1%, MBP vs no MBP; OR 1.062, 95% CI 0.584–1.933, P = 0.844) (Table 2, Fig. 3).
Three studies (n = 740) examined postoperative mortality. There was no significant difference in mortality between patients who did not receive MBP prior to undergoing rectal resection and those who did (2.1% vs 2.8%, MBP vs no MBP; OR 1.377, 95% CI 0.549–3.455, P = 0.495) (Table 2, Fig. 5). Analysis of the funnel plot (Fig. 6) demonstrated across-trial publication bias, but the Begg–Mazumdar (P = 0.359) and Egger (P = 0.372) tests did not reach statistical significance.
Surgical site infection Four studies (n = 840) examined postoperative surgical site infection. There was no difference in the rate of surgical site infection between those receiving MBP preoperatively and those not (10.8% vs 9.9%, MBP vs no MBP; OR 0.946, 95% CI 0.597–1.498, P = 0.812) (Table 2, Fig. 4a). Three studies (n = 740) examined postoperative abscess formation. Though there was a
Discussion The present meta-analysis does not demonstrate a beneficial effect of MBP prior to protectomy with respect to anastomotic leakage, surgical site infection, abscess formation or overall postoperative morbidity and mortality.
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Statistics for each study
Study name Odds ratio Burke P. Br J Surg ‘94 Santos J. Br J Surg ‘94 Miettinen P. Dis Colon Rectum ‘00 Jung B. Br J Surg ‘06 Bretagnol F. Br J Surg ‘07 Evans J. ACPGBI ‘08 Leiro F. Rev Argent Cirug ‘08 Mahadavan L. ESCP ‘08 Bretagnol F. Ann Surg ‘10 Van’t Sant H. Ann Surg ‘10 Kim Y. Yonsei Med J. ‘14
Odds ratio and 95% CI
Lower Upper limit limit Z-value P-value
1.500 0.704 0.333 0.200 1.051 1.036 2.769 0.240 2.391 0.852 2.667 1.144
0.312 7.216 0.506 0.091 5.444 –0.337 0.043 2.564 –1.056 0.010 4.123 –1.042 0.374 2.953 0.093 0.254 4.216 0.049 0.264 29.047 0.849 0.013 4.463 –0.957 0.974 5.870 1.902 0.413 1.758 –0.433 0.492 14.445 1.138 0.767 1.708 0.660
0.613 0.736 0.291 0.297 0.926 0.961 0.396 0.339 0.057 0.665 0.255 0.509 0.01
0.1 MBP
1
10
100
No MBP
Figure 2 Meta-analysis of the association of mechanical bowel preparation (MBP) with anastomotic leakage. Each study is shown by the point of the odds ratio (OR, square proportional to the weight of each study) and 95% confidence interval (CI) for the OR (extending lines); the combined ORs and 95% CIs by random effects calculations are shown by diamonds. OR 1.144, 95% CI 0.767–1.708, P = 0.509. Total n = 1258; Cochran Q = 8.8 (df = 10), P = 0.543; I² = 0.0%. Table 2 Secondary outcomes Bretagnol [20] n (%) 30-day morbidity MBP 31 (50.8) No MBP 16 (30.7) Anastomotic leakage Overall MBP 9 (14.7) No MBP 8 (15.3) Asymptomatic MBP 4 (6.5) No MBP 3 (5.7) Clinical MBP 9 14.7) No MBP 5 (9.6) Abdominopelvic abscess MBP 4 (6.5) No MBP 2 (3.8) Surgical site infection (all) MBP 2 (3.2) No MBP 0 (0) Reoperations MBP NA No MBP NA Mean length of stay (days) MBP 12 No MBP 10 30-day mortality MBP 0 (0) No MBP 1 (1.9)
Van’t Sant [2] n (%)
Bretagnol [7] n (%)
Kim [24] n (%)
92 (38.9) 83 (38.9)
24 (26.9) 39 (43.8)
39 (78) 36 (72)
18 (7.6) 14 (6.5)
8 (8.9) 17 (19.1)
2 (4) 5 (10)
NA NA
2 (2.2) 3 (3.3)
NA NA
NA NA
6 (6.7) 14 (15.7)
NA NA
6 (2.5) 9 (4.2)
1 (1.1) 7 (7.8)
NA NA
39 (16.5) 36 (16.9)
3 (3.3) 1 (1.1)
3 (6) 3 (6)
NA NA
5 (5.6) 12 (13.4)
1 (2) 7 (14)
NA NA
14 16
NA NA
7 (2.9) 9 (4.2)
1 (1.1) 0 (0)
NA NA
NA, not assessed; MBP, mechanical bowel preparation.
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Study name
Odds ratio and 95% CI
Statistics for each study Odds ratio
Lower limit
Upper limit
Bretagnol F. Br J Surg ‘07
2.325
1.072
Bretagnol F. Ann Surg ‘10
0.473
0.253
Van’t Sant H. Ann Surg ‘10
1.001
Kim Y. Yonsei Med J. ‘14
Z-value
P-value
5.041
2.137
0.033
0.887
–2.334
0.020
0.684
1.463
0.003
0.997
1.379
0.555
3.427
0.692
0.489
1.062
0.584
1.933
0.197
0.884 0.01
0.1
1
MBP
10
100
No MBP
Figure 3 Meta-analysis of the association of mechanical bowel preparation (MBP) with morbidity. OR 1.062, 95% CI 0.584– 1.933, P = 0.844. Total n = 840; Cochran Q = 10.5 (df = 3), P = 0.015; I² = 71.4%.
(a) Study name
Odds ratio and 95% CI
Statistics for each study Odds Lower Upper Z-value P-value ratio limit limit
Bretagnol F. Br J Surg ‘07
0.227
0.011
4.829
–0.951
0.342
Bretagnol F. Ann Surg ‘10 0.326 Van’t Sant H. Ann Surg ‘10 1.027 Kim Y. Yonsei Med J. ‘14 1.000 0.946
0.033 0.625 0.192 0.597
3.193 1.688 5.210 1.498
–0.963 0.107 0.000 –0.238
0.336 0.915 1.000 0.812 0.01
(b) Study name
Statistics for each study
0.1 MBP
1
10 100 No MBP
Odds ratio and 95% CI
Odds Lower Upper Z-value P-value limit ratio limit Bretagnol F. Br J Surg ‘07
0.570 0.100 3.245 –0.633
0.526
Bretagnol F. Ann Surg ‘10 7.512 0.905 62.384 Van’t Sant HP. Ann Surg ‘10 1.691 0.592 4.833
1.867 0.981
0.062 0.327
1.720 0.527 5.615
0.898
0.369 0.01
0.1 MBP
1
10 100 No MBP
Figure 4 (a) Meta-analysis of the association of mechanical bowel preparation (MBP) with surgical site infection. OR 0.946, 95% CI 0.597–1.498, P = 0.812. Total n = 840; Cochran Q = 1.8 (df = 3), P = 0.618; I² = 0.0%. (b) Meta-analysis of the association of MBP with pelvic abscess formation. OR 1.720, 95% CI 0.527–5.615, P = 0.369. Total n = 740; Cochran Q = 3.4 (df = 2), P = 0.182; I² = 41.3%.
The proposal of having bowel preparation-free surgery has been advocated as a ‘more friendly’ approach for the patient [25]. Indeed, MBP is both time-consuming and an unpleasant process for patients [2]. Jung et al. [26] showed that patient adherence to bowel preparation instructions is poor; with many less willing to have similar procedures again if MBP is necessary. Additionally, MBP has been shown to have drawbacks, including electrolyte disturbance, bacterial translocation and renal
impairment in elderly patients due to dehydration [1,27]. Some studies have observed that poor preparation results in more intra-operative faecal contamination and spillage, with increased risk of postoperative infectious complications [28], while Yeh et al. [29] demonstrated that poor colonic preparation was an independent risk factor for anastomotic leakage. Though MBP may not reduce the incidence of anastomotic leakage, it has been speculated that it may reduce
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Statistics for each study
Study name Odds ratio
Lower Upper limit limit
Bretagnol F. Br J Surg ‘07
3.583
0.143
Bretagnol F. Ann Surg ‘10
0.330
Van’t Sant HP. Ann Surg ‘10
1.443 1.377
Odds ratio and 95% CI
Z-value
P-value
89.839
0.776
0.438
0.013
8.201
–0.677
0.499
0.528
3.945
0.715
0.475
0.549
3.455
0.682
0.495 0.01
0.1 MBP
1
10
100
No MBP
Figure 5 Meta-analysis of the association of mechanical bowel preparation (MBP) with mortality. OR 1.377, 95% CI 0.549–3.455, P = 0.495. Total n = 740; Cochran Q = 1.1 (df = 2), P = 0.575; I² = 0.0%.
the severity of a leak – but although plausible, there is limited evidence available to confirm this. Bretagnol et al. [20] published preliminary evidence that proctectomy could be performed safely without using preoperative MBP. In their retrospective, nonrandomized study those not receiving preoperative MBP had a significant reduction in overall morbidity and postoperative extra-abdominal infectious complications compared with those who did. They also had a shorter length of hospital stay. They concluded that the use of MBP before anterior resection afforded no advantage in terms of morbidity. The subsequent paper of Bretagnol et al. [7], in contrast, demonstrated that rectal resection without preoperative MBP was significantly associated with an increase of the 30-day overall morbidity and infectious complication rates. In addition, there was a trend towards an increased risk of anastomotic leakage and peritonitis, but neither was statistically significant [7]. The results of Van’t Sant et al. [2] differed, showing that in the context of rectal resection, omitting MBP prior to proctectomy did not influence the risk of anastomotic leakage or other septic complications. There are some limitations to the current study, including heterogeneity of the included studies and rel-
atively small patient numbers. There were only four studies with extractable data tor 75% of the end-points assessed. In addition, there is considerable variation in the bowel preparation agents used and their method of administration, which contributes to this heterogeneity. A standard format for both outcome reporting and the type and method of bowel preparation would be a welcome addition to future studies. Based on the current data, an appropriately powered trial to explore if MBP reduces the risk of anastomotic leakage following rectal resection would require 10 540 patients to have an 80% chance of demonstrating superiority. It is unlikely such a trial would be conducted, and perhaps the best evidence we have is from pooled analysis. In conclusion no benefit or deleterious effect of MBP prior to rectal resection was demonstrated by this review. Therefore, preference of individual surgeons remains the primary determinant of whether MBP will be used.
Conflicts of interest All authors declare they have no conflict of interest.
Funding No funding sources to disclose.
0.3 Standard error
References 0.8
1.3
1.8 –5.0
–2.5
0.0 Log (Odds ratio)
2.5
Figure 6 Funnel plot to assess publication bias.
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5.0
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17 Santos JC Jr, Batista J, Sirimarco MT, Guimar€aes AS, Levy CE. Prospective randomized trial of mechanical bowel preparation in patients undergoing elective colorectal surgery. Br J Surg 1994; 81: 1673–6. 18 Miettinen RP, Laitinen ST, M€akel€a JT, P€a€akk€ onen ME. Bowel preparation with oral polyethylene glycol electrolyte solution vs. no preparation in elective open colorectal surgery: prospective, randomized study. Dis Colon Rectum 2000; 43: 669–75; discussion 75-7. 19 Jung B. Mechanical bowel preparation for rectal surgery without preparation. 2006. 20 Bretagnol F, Alves A, Ricci A, Valleur P, Panis Y. Rectal cancer surgery without mechanical bowel preparation. Br J Surg 2007; 94: 1266–71. 21 Leiro F, Barredo C, Latif J et al. Mechanical preparation in elective colon and rectal surgery. Rev Argent Cir 2008; 95: 154–67. 22 Evans J, Bright E, Norwood M, Kellar A, Scott DN, Jameson JS. Use of bowel prep does not affect leak rate in anterior resection. The Association of Coloproctology in Great Britain and Ireland Journal Compilation. 2008; Poster Presentation (Poster P087). 23 Mahadavan L, Daniels I. How much more evidence do we need to mechanical bowel preparation? European Society of Coloproctology Journal Compilation. Poster Presentation. 2008;P18. 24 Kim YW, Choi EH, Kim IY, Kwon HJ, Ahn SK. The impact of mechanical bowel preparation in elective colorectal surgery: a propensity score matching analysis. Yonsei Med J 2014; 55: 1273–80. 25 Khoo CK, Vickery CJ, Forsyth N, Vinall NS, Eyre-Brook IA. A prospective randomized controlled trial of multimodal perioperative management protocol in patients undergoing elective colorectal resection for cancer. Ann Surg 2007; 245: 867–72. 26 Jung B, Lannerstad O, Pahlman L, Arodell M, Unosson M, Nilsson E. Preoperative mechanical preparation of the colon: the patient’s experience. BMC Surg 2007; 7: 5. 27 Beloosesky Y, Grinblat J, Weiss A, Grosman B, Gafter U, Chagnac A. Electrolyte disorders following oral sodium phosphate administration for bowel cleansing in elderly patients. Arch Intern Med 2003; 163: 803–8. 28 Mahajna A, Krausz M, Rosin D et al. Bowel preparation is associated with spillage of bowel contents in colorectal surgery. Dis Colon Rectum 2005; 48: 1626–31. 29 Yeh CY, Changchien CR, Wang JY et al. Pelvic drainage and other risk factors for leakage after elective anterior resection in rectal cancer patients: a prospective study of 978 patients. Ann Surg 2005; 241: 9–13.
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Postoperative outcomes following mechanical bowel preparation before proctectomy: a meta-analysis D. E. Courtney, M. E. Kelly, J. P. Burke and D. C. Winter Centre for Colorectal Disease, St Vincent’s University Hospital, Dublin, Ireland Received 8 October 2014; accepted 14 March 2015; Accepted Article online 11 June 2015
Abstract Aim Previous meta-analyses of mechanical bowel preparation (MBP) before colorectal surgery have grouped colon and rectal resection together. An increased postoperative morbidity has been suggested in the absence of MBP following proctectomy. The current study used meta-analytical techniques to evaluate the comparative outcome of patients who received MBP prior to proctectomy. Method A comprehensive search was performed for published studies examining the effect of MBP before proctectomy on patient outcome. Random effects methods were used to combine data. Results Eleven studies including 1258 patients were identified. There was no significant difference in overall
Introduction Mechanical bowel preparation (MBP) before colorectal resection is questionable and controversial in the modern perioperative care of colorectal patients [1,2]. While early analyses suggested a higher rate of anastomotic leakage following MBP [3,4], more recent studies of larger patient cohorts have refuted this, but they still suggest MBP is associated with a higher rate of surgical site infection [1]. Although there is considerable consensus regarding the abandonment of MBP in elective colorectal surgery, many surgeons are hesitant in eliminating its use before proctectomy [5,6]. To date, meta-analyses on this subject have grouped colonic and rectal resection, but a recent randomized controlled trial has suggested an improved outcome following MBP before proctectomy [7]. As a pelvic anastomosis is an independent risk factor for anastomotic leakage [8], most colorectal surgeons still use MBP Correspondence to: Danielle E Courtney, Department of Surgery, St Vincent’s University Hospital, Elm Park, Dublin 4, Ireland. E-mail: [email protected]
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morbidity (OR 1.062, 95% CI 0.584–1.933, P = 0.844), anastomotic leakage (OR 1.144, 95% CI 0.767–1.708, P = 0.509), surgical site infection (OR 0.946, 95% CI 0.549–1.498, P = 0.812) or mortality (OR 1.377, 95% CI 0.549–3.455, P = 0.495) between those who did not and those who did receive MBP prior to proctectomy. Conclusion The current study did not demonstrate a beneficial effect of MBP prior to proctectomy, but the data were limited. Decision-making as to its use should be made on a case-by-case basis. Keywords Rectal surgery, surgical outcomes, surgical morbidity, anastomotic leak, mechanical bowel preparation
before rectal cancer surgery [9] in the hope of reducing the incidence and severity of this potentially fatal complication [10,11]. A consensus must be reached from the published literature that focuses on the efficacy and safety of omitting MBP before proctectomy before this practice can be advocated. To address this, we performed a meta-analysis of all published data examining the omission of MBP before proctectomy. The aim of this study was to assess the comparative incidence of anastomotic leakage, pelvic abscess, overall morbidity and inpatient mortality in patients having and not having MBP.
Method Literature search and study selection
A systematic search of the Pubmed and Embase databases was performed for all papers published relating to MBP in the context of rectal resection and its association with postoperative morbidity and mortality. We used the following search algorithm: (rectal OR rectum
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OR proctectomy) AND (resection OR surgery) AND (bowel) AND (cleansing OR preparation). The abstracts of the American Society of Colon and Rectal Surgeons, the Association of Coloproctology of Great Britain and Ireland, the European Society of Coloproctology and the Tripartite Meetings from 2000 to 2013 were screened for relevant (Table 1). We also searched the Cochrane Central Register of Controlled Trials for articles comparing outcomes after proctectomy in those who received MBP and those who did not. The most recent search was performed on 2 January 2015. Two authors (DC and MK) independently performed the searches and reviewed all identified publications and abstracts for inclusion. The full texts of potentially eligible trials were obtained. The reference lists of retrieved papers were further reviewed for additional eligible papers. Discrepancies were identified and resolved by discussion. There were no language restrictions. Individual manuscript quality/risk of bias was also determined by two independent assessors (DC and MK). For nonrandomized studies, the quality of studies was evaluated using the Newcastle–Ottawa Scale [12] which examines three items – patient selection, comparability of the two study groups and assessment of exposure (maximum score 9). For randomized controlled trials, the quality of studies was evaluated using the Jadad scoring system [13] which examines three items – randomization, blinding and withdrawals/dropouts (maximum score 5). Eligibility criteria
To be included, publications were required to compare the postoperative clinical outcomes of patients undergoing rectal resection who were given MBP preoperatively with those who were not. The primary outcome of the study was to assess the incidence of anastomotic leakage in patients undergoing proctectomy with or without preoperative MBP. The secondary outcomes were morbidity, surgical site infection, pelvic abscess formation and mortality. Studies that did not provide data on rectal resections exclusively were excluded. Data extraction and outcomes
Data from the identified studies were extracted independently by two authors (DC and MK) and confirmed by both. The following individual data regarding each eligible trial were extracted using standardized extraction forms: general data (author’s name, study design, year of publication, enrolment interval); characteristics of patients (number, mean age); main features of interventions (type of MBP) and clinical outcome (mortality,
Outcomes after mechanical bowel preparation before proctectomy
morbidity, anastomotic leakage, surgical site infection and abdominopelvic abscess). When data were unclear or incomplete, the corresponding author was contacted to clarify data extraction. Statistical analysis
All pooled outcome measures were determined using a random effects model as described by DerSimonian and Laird [14] and the odds ratio was estimated with its variance and 95% CI. The random effects analysis weighted the natural logarithm of each study’s OR by the inverse of its variance plus an estimate of the between-study variance in the presence of betweenstudy heterogeneity. As previously described, heterogeneity between ORs for the same outcome between different studies was assessed [15]. This was through the use of the I2 inconsistency test and the chi-squared based Cochran’s Q statistic test in which P < 0.05 is taken to indicate the presence of significant heterogeneity. Analyses were conducted using COMPREHENSIVE META-ANALYSIS version 2 (Biostat Inc., Englewood, New Jersey, USA).
Results Eligible studies
Of the 785 publications identified by the initial search, 53 full text articles were reviewed for eligibility. 732 publications were excluded after screening their title and abstract. A further 42 published articles were not included on the basis that they did not contain data on rectal operations exclusively (n = 29), did not compare the role of preoperative use of MBP (n = 1), they were meta-analyses (n = 8) or they were not relevant (n = 4). Eleven publications were thus included in the final analysis for anastomotic leakage rate, with a total of 1258 patients. Four studies with a total of 840 patients had extractable data regarding postoperative morbidity and surgical site infection rates, while three studies with a total of 740 patients had extractable data regarding pelvic abscess formation and mortality rates (Fig. 1). Primary outcome
Anastomotic leakage Eleven studies (n = 1258) compared the rate of anastomotic leakage with and without MBP prior to rectal surgery. Table 1 outlines patient demographics and the type of MBP used. No significant difference was observed in the rate of anastomotic leakage between
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863
864 NA
50 21 29 Laxative + enema + mannitol
N 1
2
75 39 36 Picolax
Multicentre Number of centres Number of surgeons Patients n (total) n (MBP) n (no MBP) Preparation type
62 50 NA 61 NA
23 9 14 PEG-ELS
NA
Y 2
3 (Jadad score) Finland
2000 RCT 2 years
Miettinen [18]
-
44 27 17 -
NA
Y 21
4 (Jadad score) Sweden
2006 RCT –
Jung [19]
63 100 42 87 NA
113 61 52 X-PREP sarget
1
N 1
France
7 (NO score)
2007 Retrospective 5 years
Bretagnol [20]
65 69 NA NA NA
27 10 17 Sodium phosphate or PEG
NA
N 1
3 (Jadad score) Argentina
2008 RCT 19 months
Leiro [21]
-
73 40 33 Phosphosoda
2
Cannot assess United Kingdom N 1
2008 Retrospective –
Evans [22]
-
126 7 119 Picolax
1
United Kingdom N 1
Cannot assess
2008 Retrospective –
Mahadavan [23]
MBP, mechanical bowel preparation; N, no; Y, yes; NA, not assessed; RCT, randomized controlled trial; NO, Newcastle–Ottawa score.
50 46 NA NA NA
N 1
Ireland
Country
66 89 NA 86 NA
3 (Jadad score) Brazil
4 (Jadad score)
Mean age Malignancy (%) Radiotherapy (%) Stapled (%) Stoma end (%)
1994 RCT 15 months
1994 RCT 4 years
Santos [17]
Year Study design Enrolment interval Paper quality
Burke [16]
Study
Table 1 Study characteristics
449 236 213 PEG + bisacodyl or sodium phosphate NA 7 6 7 6
NA
Y 13
3 (Jadad score) Netherlands
2010 RCT 71 months
Van’t Sant [2]
63 100 NA 54 82
178 89 89 X-PREP sarget
NA
Y 8
4 (Jadad score) France
2010 RCT 16 months
Bretagnol [7]
67 97 NA NA NA
100 50 50 PEG
NA
N 1
8 (NO score) Korea
2014 Retrospective 24 months
Kim [24]
Outcomes after mechanical bowel preparation before proctectomy D. E. Courtney et al.
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Outcomes after mechanical bowel preparation before proctectomy
Records identified through database searching (n = 786) Pubmed (780) Cochrane (3) Embase (0) Grey Lit (3)
Records after duplicates removed (n = 785)
Figure 1 The Preferred Reporting Items for Systematic Reviews and MetaAnalyses (PRISMA) flow diagram. Grey Lit, grey literature review: defined as ‘that which is produced on all levels of government, academics, business and industry in print and electronic formats, but which is not controlled by commercial publishers’ (The 4th International Conference on Grey Literature, 1999). MBP, mechanical bowel preparation.
Full-text articles assessed for eligibillity (n = 53)
Studies included in meta-analysis (n = 11)
those receiving and those not receiving MBP preoperatively (8.7% vs 10.3%, MBP vs no MBP; OR 1.144, 95% CI 0.767–1.708, P = 0.509) (Fig. 2). Secondary outcomes
Articles excluded by title & abstract (n = 732) -Review article (71) -Retracted articles (1) -About endoscopy (116) -Not about MBP (249) -Comparison of MBPs (38) -Not about proctecomy (257)
Full text articles excluded (n = 42) -Not exclusively rectal (29) -No comparison made (1) -Meta-analyses (8) -Not relevant (4) Total n = 1 258 patients
trend towards increased abscess formation postoperatively in those not receiving MBP, it was, however, not statistically significant (2.8% vs 5.1%, MBP vs no MBP; OR 1.720, 95% CI 0.527–5.615, P = 0.369) (Table 2, Fig. 4b).
Morbidity
Mortality
Four studies (n = 840) compared the rate of overall postoperative morbidity in those who underwent rectal resection with or without preoperative MBP. No significant difference was observed between those receiving and those not receiving MBP preoperatively in the rate of postoperative morbidity (42.7% vs 43.1%, MBP vs no MBP; OR 1.062, 95% CI 0.584–1.933, P = 0.844) (Table 2, Fig. 3).
Three studies (n = 740) examined postoperative mortality. There was no significant difference in mortality between patients who did not receive MBP prior to undergoing rectal resection and those who did (2.1% vs 2.8%, MBP vs no MBP; OR 1.377, 95% CI 0.549–3.455, P = 0.495) (Table 2, Fig. 5). Analysis of the funnel plot (Fig. 6) demonstrated across-trial publication bias, but the Begg–Mazumdar (P = 0.359) and Egger (P = 0.372) tests did not reach statistical significance.
Surgical site infection Four studies (n = 840) examined postoperative surgical site infection. There was no difference in the rate of surgical site infection between those receiving MBP preoperatively and those not (10.8% vs 9.9%, MBP vs no MBP; OR 0.946, 95% CI 0.597–1.498, P = 0.812) (Table 2, Fig. 4a). Three studies (n = 740) examined postoperative abscess formation. Though there was a
Discussion The present meta-analysis does not demonstrate a beneficial effect of MBP prior to protectomy with respect to anastomotic leakage, surgical site infection, abscess formation or overall postoperative morbidity and mortality.
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Statistics for each study
Study name Odds ratio Burke P. Br J Surg ‘94 Santos J. Br J Surg ‘94 Miettinen P. Dis Colon Rectum ‘00 Jung B. Br J Surg ‘06 Bretagnol F. Br J Surg ‘07 Evans J. ACPGBI ‘08 Leiro F. Rev Argent Cirug ‘08 Mahadavan L. ESCP ‘08 Bretagnol F. Ann Surg ‘10 Van’t Sant H. Ann Surg ‘10 Kim Y. Yonsei Med J. ‘14
Odds ratio and 95% CI
Lower Upper limit limit Z-value P-value
1.500 0.704 0.333 0.200 1.051 1.036 2.769 0.240 2.391 0.852 2.667 1.144
0.312 7.216 0.506 0.091 5.444 –0.337 0.043 2.564 –1.056 0.010 4.123 –1.042 0.374 2.953 0.093 0.254 4.216 0.049 0.264 29.047 0.849 0.013 4.463 –0.957 0.974 5.870 1.902 0.413 1.758 –0.433 0.492 14.445 1.138 0.767 1.708 0.660
0.613 0.736 0.291 0.297 0.926 0.961 0.396 0.339 0.057 0.665 0.255 0.509 0.01
0.1 MBP
1
10
100
No MBP
Figure 2 Meta-analysis of the association of mechanical bowel preparation (MBP) with anastomotic leakage. Each study is shown by the point of the odds ratio (OR, square proportional to the weight of each study) and 95% confidence interval (CI) for the OR (extending lines); the combined ORs and 95% CIs by random effects calculations are shown by diamonds. OR 1.144, 95% CI 0.767–1.708, P = 0.509. Total n = 1258; Cochran Q = 8.8 (df = 10), P = 0.543; I² = 0.0%. Table 2 Secondary outcomes Bretagnol [20] n (%) 30-day morbidity MBP 31 (50.8) No MBP 16 (30.7) Anastomotic leakage Overall MBP 9 (14.7) No MBP 8 (15.3) Asymptomatic MBP 4 (6.5) No MBP 3 (5.7) Clinical MBP 9 14.7) No MBP 5 (9.6) Abdominopelvic abscess MBP 4 (6.5) No MBP 2 (3.8) Surgical site infection (all) MBP 2 (3.2) No MBP 0 (0) Reoperations MBP NA No MBP NA Mean length of stay (days) MBP 12 No MBP 10 30-day mortality MBP 0 (0) No MBP 1 (1.9)
Van’t Sant [2] n (%)
Bretagnol [7] n (%)
Kim [24] n (%)
92 (38.9) 83 (38.9)
24 (26.9) 39 (43.8)
39 (78) 36 (72)
18 (7.6) 14 (6.5)
8 (8.9) 17 (19.1)
2 (4) 5 (10)
NA NA
2 (2.2) 3 (3.3)
NA NA
NA NA
6 (6.7) 14 (15.7)
NA NA
6 (2.5) 9 (4.2)
1 (1.1) 7 (7.8)
NA NA
39 (16.5) 36 (16.9)
3 (3.3) 1 (1.1)
3 (6) 3 (6)
NA NA
5 (5.6) 12 (13.4)
1 (2) 7 (14)
NA NA
14 16
NA NA
7 (2.9) 9 (4.2)
1 (1.1) 0 (0)
NA NA
NA, not assessed; MBP, mechanical bowel preparation.
866
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Study name
Odds ratio and 95% CI
Statistics for each study Odds ratio
Lower limit
Upper limit
Bretagnol F. Br J Surg ‘07
2.325
1.072
Bretagnol F. Ann Surg ‘10
0.473
0.253
Van’t Sant H. Ann Surg ‘10
1.001
Kim Y. Yonsei Med J. ‘14
Z-value
P-value
5.041
2.137
0.033
0.887
–2.334
0.020
0.684
1.463
0.003
0.997
1.379
0.555
3.427
0.692
0.489
1.062
0.584
1.933
0.197
0.884 0.01
0.1
1
MBP
10
100
No MBP
Figure 3 Meta-analysis of the association of mechanical bowel preparation (MBP) with morbidity. OR 1.062, 95% CI 0.584– 1.933, P = 0.844. Total n = 840; Cochran Q = 10.5 (df = 3), P = 0.015; I² = 71.4%.
(a) Study name
Odds ratio and 95% CI
Statistics for each study Odds Lower Upper Z-value P-value ratio limit limit
Bretagnol F. Br J Surg ‘07
0.227
0.011
4.829
–0.951
0.342
Bretagnol F. Ann Surg ‘10 0.326 Van’t Sant H. Ann Surg ‘10 1.027 Kim Y. Yonsei Med J. ‘14 1.000 0.946
0.033 0.625 0.192 0.597
3.193 1.688 5.210 1.498
–0.963 0.107 0.000 –0.238
0.336 0.915 1.000 0.812 0.01
(b) Study name
Statistics for each study
0.1 MBP
1
10 100 No MBP
Odds ratio and 95% CI
Odds Lower Upper Z-value P-value limit ratio limit Bretagnol F. Br J Surg ‘07
0.570 0.100 3.245 –0.633
0.526
Bretagnol F. Ann Surg ‘10 7.512 0.905 62.384 Van’t Sant HP. Ann Surg ‘10 1.691 0.592 4.833
1.867 0.981
0.062 0.327
1.720 0.527 5.615
0.898
0.369 0.01
0.1 MBP
1
10 100 No MBP
Figure 4 (a) Meta-analysis of the association of mechanical bowel preparation (MBP) with surgical site infection. OR 0.946, 95% CI 0.597–1.498, P = 0.812. Total n = 840; Cochran Q = 1.8 (df = 3), P = 0.618; I² = 0.0%. (b) Meta-analysis of the association of MBP with pelvic abscess formation. OR 1.720, 95% CI 0.527–5.615, P = 0.369. Total n = 740; Cochran Q = 3.4 (df = 2), P = 0.182; I² = 41.3%.
The proposal of having bowel preparation-free surgery has been advocated as a ‘more friendly’ approach for the patient [25]. Indeed, MBP is both time-consuming and an unpleasant process for patients [2]. Jung et al. [26] showed that patient adherence to bowel preparation instructions is poor; with many less willing to have similar procedures again if MBP is necessary. Additionally, MBP has been shown to have drawbacks, including electrolyte disturbance, bacterial translocation and renal
impairment in elderly patients due to dehydration [1,27]. Some studies have observed that poor preparation results in more intra-operative faecal contamination and spillage, with increased risk of postoperative infectious complications [28], while Yeh et al. [29] demonstrated that poor colonic preparation was an independent risk factor for anastomotic leakage. Though MBP may not reduce the incidence of anastomotic leakage, it has been speculated that it may reduce
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Statistics for each study
Study name Odds ratio
Lower Upper limit limit
Bretagnol F. Br J Surg ‘07
3.583
0.143
Bretagnol F. Ann Surg ‘10
0.330
Van’t Sant HP. Ann Surg ‘10
1.443 1.377
Odds ratio and 95% CI
Z-value
P-value
89.839
0.776
0.438
0.013
8.201
–0.677
0.499
0.528
3.945
0.715
0.475
0.549
3.455
0.682
0.495 0.01
0.1 MBP
1
10
100
No MBP
Figure 5 Meta-analysis of the association of mechanical bowel preparation (MBP) with mortality. OR 1.377, 95% CI 0.549–3.455, P = 0.495. Total n = 740; Cochran Q = 1.1 (df = 2), P = 0.575; I² = 0.0%.
the severity of a leak – but although plausible, there is limited evidence available to confirm this. Bretagnol et al. [20] published preliminary evidence that proctectomy could be performed safely without using preoperative MBP. In their retrospective, nonrandomized study those not receiving preoperative MBP had a significant reduction in overall morbidity and postoperative extra-abdominal infectious complications compared with those who did. They also had a shorter length of hospital stay. They concluded that the use of MBP before anterior resection afforded no advantage in terms of morbidity. The subsequent paper of Bretagnol et al. [7], in contrast, demonstrated that rectal resection without preoperative MBP was significantly associated with an increase of the 30-day overall morbidity and infectious complication rates. In addition, there was a trend towards an increased risk of anastomotic leakage and peritonitis, but neither was statistically significant [7]. The results of Van’t Sant et al. [2] differed, showing that in the context of rectal resection, omitting MBP prior to proctectomy did not influence the risk of anastomotic leakage or other septic complications. There are some limitations to the current study, including heterogeneity of the included studies and rel-
atively small patient numbers. There were only four studies with extractable data tor 75% of the end-points assessed. In addition, there is considerable variation in the bowel preparation agents used and their method of administration, which contributes to this heterogeneity. A standard format for both outcome reporting and the type and method of bowel preparation would be a welcome addition to future studies. Based on the current data, an appropriately powered trial to explore if MBP reduces the risk of anastomotic leakage following rectal resection would require 10 540 patients to have an 80% chance of demonstrating superiority. It is unlikely such a trial would be conducted, and perhaps the best evidence we have is from pooled analysis. In conclusion no benefit or deleterious effect of MBP prior to rectal resection was demonstrated by this review. Therefore, preference of individual surgeons remains the primary determinant of whether MBP will be used.
Conflicts of interest All authors declare they have no conflict of interest.
Funding No funding sources to disclose.
0.3 Standard error
References 0.8
1.3
1.8 –5.0
–2.5
0.0 Log (Odds ratio)
2.5
Figure 6 Funnel plot to assess publication bias.
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5.0
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