Author Affiliations: Department of General Surgery, Shanghai Jiaotong University Affiliated First People's Hospital, Shanghai 200080, China (Xia X, Huang C, Cen G and Qiu ZJ)

Corresponding Author: Zheng-Jun Qiu, MD, PhD, Department of General Surgery, Shanghai Jiaotong University Affiliated First People's Hospital, 100 Haining Road, Shanghai 200080, China (Tel: +86-21-63240825; Fax: +86-21-63240090; Email: qiuzjdoctor@sina.com)

 

© 2015, Hepatobiliary Pancreat Dis Int. All rights reserved.

doi: 10.1016/S1499-3872(15)60330-7

Published online January 2, 2015.

 

 

Contributors: XX proposed the study. CG performed research and wrote the first draft. HC collected and analyzed the data. All authors contributed to the design and interpretation of the study and to further drafts. QZJ is the guarantor.

Funding: This study was supported by grants from the National Natural Science Foundation of China (81372640, 81101844 and 81210108027), Shanghai Municipal Human Resources and Social Security Bureau (2012040 and 13PJD024) and Shanghai Municipal Health Bureau (13Y068).

Ethical approval: Not needed.

Competing interest: No benefits in any form have been received or will be received from a commercial party related directly or indirectly to the subject of this article.

 

BACKGROUND: The role of diabetes mellitus (DM) in pancreatic fistula (PF) or clinical relevant PF (CR-PF) after pancreaticoduodenectomy (PD) or pylorus-preserving pancreaticoduodenectomy (PPPD) is unclear. We conducted a meta-analysis to investigate the relationship between DM and PF or CR-PF.

 

DATA SOURCES: Embase, MEDLINE and Cochrane databases were searched systematically for relevant articles from January 2005 to June 2013. The selected studies that examined clinical risk factors of PF or CR-PF were included. We created pooled estimates for our outcomes using the random-effects model.

 

RESULTS: Sixteen observational clinical studies were included. Pooling of PF rates from ten studies revealed that DM was associated with a decreased risk of PF (P=0.01). CR-PF rates from 8 studies showed no significant difference between DM and control group (P=0.14).

 

CONCLUSIONS: DM is not a risk factor for PF in patients undergoing PD or PPPD. On the contrary, patients without DM are at a higher risk of PF because the pancreases in these patients have more fatty tissue and the pancreas is soft.

 

(Hepatobiliary Pancreat Dis Int 2015;14:132-138)

 

KEY WORDS: pancreatic fistula; diabetes; postoperative complication

Pancreaticoduodenectomy (PD) is the well-known standard resection for various benign and malignant diseases of the periampullary region.^{[1, 2]} The advances in operative techniques and postoperative management have greatly improved the safety of PD worldwide, the patients' perioperative mortality rates are significantly decreased and the quality of patients' life after PD was significantly improved.^{[3, 4]} However, this complicated surgical procedure historically regarded as high operative mortality and morbidity,^{[5, 6]} with 30%-40% of patients experiencing one or more postoperative complications.^[7]

 

Pancreatic fistula (PF) is the most common complication after PD, with a frequency ranging from 2% to 20%. PF is associated with a longer hospital stay and more costs.^{[6, 8]} In addition, PF could be related to some potentially life-threatening complications such as intra-abdominal hemorrhage and abscess, possibly leading to death. There are several risk factors for PF. The quality of the pancreatic parenchyma, such as soft pancreatic texture, non-dilated principal pancreatic duct or a thick pancreatic stump has been considered as the main risk factor.^{[9, 10]} Obesity or high BMI is another risk factor causing a "fatty pancreas".^{[11, 12]} A number of techniques have also been proposed to reduce PF following PD, such as the use of the somatostain analogue octreotide,^[13] reinforcing anastomosis with fibrin glue,^[14] and placement of a pancreatic duct stent.^{[15, 16]}

 

However, the role of diabetes mellitus (DM) in this setting is unclear. The correlation between DM and pancreatic ductal adenocarcinoma is well established.^[17] Meanwhile, perioperative DM, especially if poorly controlled, has been shown to significantly impact postoperative complications after different operations.^[18] In pancreatic resection, some studies showed that DM is a significant risk factor for PF after PD.^[19-21] On the contrary, others revealed that patients with DM did not show a greater rate of PF as compared with non-DM patients.^[22-25] Because of the controversial results of these studies, we performed a meta-analysis focusing on the relationship between DM and PF in patients undergoing conventional PD or pylorus-preserving pancreaticoduodenectomy (PPPD).

 

 

This meta-analysis was conducted according to the "meta-analysis of observational studies in epidemiology: a proposal for reporting".^[26]

 

Embase, MEDLINE and Cochrane databases were searched to identify relevant articles published from January 2005 to June 2013. The search terms included "pancreaticoduodenectomy" or "pylorus-preserving pancreaticoduodenectomy" or "whipple" or "pancreatic surgery" or "pancreatic resection"; "pancreatic fistula" or "pancreatic leak" or "anastomotic leak"; "diabetes" or "diabetes mellitus". Then the reference lists of relevant articles were manually searched to find other potentially eligible studies. No language restrictions were applied and our search was limited to humans only. All searches were performed by two independent reviewers (XX and HC).

 

The titles and abstracts of the search results were screened for eligible studies. All cohort studies (prospective and retrospective) and all case-control studies that investigated DM directly influencing the occurrence of PF after PD or PPPD were included. The following were excluded: abstracts only, comments, letters, expert opinions, reviews without original data, case reports, studies with distal pancreatectomy or pancreatic enucleation and studies without a control group. Both investigators (XX and HC) assessed all articles by these above criteria and scored on a standardized form. Disagreement was resolved by consensus; when this failed, a third investigator adjudicated. We contacted the authors to get missing data when important information in the published articles was not adequate.

 

The primary outcome evaluation was the incidence of PF, as described by the International Study Group on Pancreatic Fistula (ISGPF).^[6] Output via an operative placed drain (or a subsequently placed, percutaneous drain) of any measurable volume of drain fluid on or after postoperative day 3, with an amylase content greater than 3 times of the upper normal serum value. Then three different grades were defined according to the patients' clinical symptom: 1. Grade A has no clinical impact and requires little intervention in management; 2. Grade B needs some intervention such as partial or total parenteral or enteral nutrition, repositioning the drainage, antibiotics and somatostain; 3. Grade C requires aggressive clinical intervention and sometimes reoperation. As the definition of the ISGPF has been commonly used for PF evaluation, any article that failed to meet this PF criterion would be eliminated.

 

The American Diabetes Association (ADA) has issued comprehensive diagnostic criteria for DM.^[27] However, the definitions of DM in the published literature do not always follow the ADA criteria. In addition to ADA, various organizations (e.g., World Health Organization, International Diabetes Association) have their own diagnostic guidelines. Second, due to the retrospective data of most our articles, the diagnosis of DM is mainly derived from medical history and self-reporting. Therefore, caution is required to compare results between studies that have different criteria for DM.

 

The following data were extracted by two independent reviewers (CG and QZJ): first author, year of publication, study design, sample size, operative techniques, DM rate, presence or absence of PF and grade if possible, and primary outcomes. Inconsistencies were resolved through discussion until consensus was made, or the third reviewer (HC) would participate in this discussion. Because patients with grade B and C PF were generally considered to show clinical symptoms differed from grade A, we defined grade B and C PF as clinical relevant PF (CR-PF) and thus categorized selected studies into two groups according to their study outcomes. In the event of multiple publications from the same cohort or overlapping series of patients, data included only once from the most recent article to avoid double counting of patients. Qualitative assessment of observational studies was based on the Newcastle-Ottawa Scale.^[28] "Good" was defined as a total score of 7-9; "Fair", 4-6; and "Poor", less than 4.

 

Meta-analyses were performed for studies which provided comparative data on the outcomes of patients who underwent PD or PPPD with or without DM. The odds ratio (OR) was chosen as an effect measure for those dichotomous parameters, which were reported along with the corresponding 95% confidence intervals (CIs) and the P<0.05 level was utilized to specify statistical significance. Heterogeneity was evaluated by inspection of the forest and I^?2 statistic; an I^?2 value of more than 50% was considered as high statistical heterogeneity.^[29] Initially, a fixed-effects model was used to synthesize all data. However, random-effects model of DerSimonian and Laird^[30] was applied if there was evidence of heterogeneity among included studies. Clinical heterogeneity could be explained by different outcome parameters, variability of interventions and perioperative management. Funnel plots were constructed to evaluate potential publication bias,^[31] based on the complication PF. All statistical analyses were performed using Review Manager 5 software (The Cochrane Collaboration, Oxford, UK).

 

 

Of 450 articles we searched, 412 were excluded after scanning titles and abstracts, leaving 38 for full-text evaluation. Of these articles, 16 were finally included in this meta-analysis (Fig. 1). Among the 16 articles, two groups were identified. Eight articles assessed the predictive risk factors for PF containing grade A, B and C (Table 1);^{[11, 12, 32-37]} six articles combined grade B and C as CR-PF and compared CR-PF patients to non-PF and grade A patients for risk factors analysis (Table 2).^{[16, 22, 38-41]} The remaining 2 articles listed patients' data in each PF grade and thus could be categorized into two groups.^{[42, 43]} The indications for PD included benign and malignant pancreatic and periampullary diseases, such as pancreatic adenocarcinoma, malignant ampulloma, chronic pancreatitis, benign ampulloma, etc. The standard operation was PD with or without pylorus-preservation, reconstructed by pancreaticogastrostomy (PG) or pancreaticojejunostomy (PJ). All identified articles followed an observational design, described "fair" or "good" in the Newcastle-Ottawa Scale.

 

Ten studies comprising 1251 patients (sample size range: 62-244) reported PF risk estimates of cohorts with DM (Table 1). The rate of DM ranged from 7.0% to 63.1%, whereas the rate of PF varied from 10.7% to 50.0%. On univariate analysis, Mathur and colleagues^[12] found that patients with DM had a significantly decreased hazard of postoperative PF following PD or PPPD. The other 9 articles, including 3 prospectively maintained databases,^{[32, 33, 37]} did not find a significant association between DM and PF in patients who underwent PD or PPPD. A meta-analysis was subsequently conducted to investigate DM as a protective factor for PF. Pooled analyses of PF by preoperative DM revealed a significant association between DM and non-PF (Fig. 2). Overall, PF occurred in 58 of 303 (19.1%) patients with diabetes and 276 of 948 (29.1%) patients without diabetes with an odds ratio of 0.64 (95% confidence interval 0.45 to 0.90, P=0.01).

 

Eight studies evaluated whether preoperative DM was associated with the higher incidence of CR-PF (Table 2). A total of 1781 patients (sample size range: 103-444) were analyzed, including 395 patients with diabetes and 1386 without diabetes. The rate of DM ranged from 7.8% to 32.0%, while the rate of PF varied from 13.3% to 28.0%. Univariate (P=0.015) and multivariate analyses (P=0.003) showed that patients without DM were more likely to develop CR-PF following PD.^[16] The other 7 articles, including 2 prospective maintained databases,^[39,40] reported that there was no significant difference between non-DM patients and DM patients with regard to CR-PF. We compared the association between DM and CR-PF by meta-analyses and found that there was no significant difference in CR-PF between the DM and control group (Fig. 3). Pooled analysis displayed the incidence of CR-PF was 11.6% in the 395 patients with DM, compared with 15.0% in the 1386 patients without DM with an odds ratio of 0.77 (95% confidence interval 0.54 to 1.09, P=0.14).

 

 

DM is considered to be one of the major and growing public health burdens in the world. The relationship between DM and pancreatic ductal adenocarcinoma (PDAC) is well-established.^[17] Additionally, approximately 20%-80% of PDAC patients have either insufficient glucose tolerance or definite DM at the time of diagnosis, which appears most frequently within only 1 or 2 years before diagnosis.^[44] DM has also been identified as a risk factor for a number of postoperative adverse events after various types of operations such as cardiac, vascular and general surgeries.^[45-47] Because of the close association between DM and PDAC, the impact of preoperative DM on postoperative course of patients undergoing PD or PPPD may be of great importance.

 

Whether preoperative DM has a significant impact on PF is not clear. In 2001, Srivastava et al^[48] analyzed 120 patients who underwent PD and had pancreaticoenteric anastomotic leakage. Multivariate logistic regression revealed that patients with preoperative DM had a significantly higher incidence of PF than those without DM (28% vs 8.4%, respectively; P<0.05). In 2004, Lin et al^[49] analyzed 1891 patients with PF. The diagnosis was either a radiologically proved anastomotic leak or the continued drainage of amylase-rich fluid on or after postoperative day 10. Univariate analysis showed that the incidence of PF in patients with preoperative DM was significantly lower than that in those without DM (7.7% vs 12.0%, P<0.05). Unlike previous studies, by pooling diabetes rates from sixteen studies, we were able to establish a large cohort to perform a statistical review and meta-analysis. Interestingly, we found that DM did not significantly increase the risk of PF or CR-PF. On the contrary, a significant trend was observed toward decreased PF in patients with DM (Fig. 2). Although there was no significant difference, patients without DM were more likely to develop CR-PF (Fig. 3). This interesting result could be explained by two reasons: 1. Pancreases in patients with DM had significantly less fat or more fibrosis (hard texture) compared with those in patients without DM.^[12,19,39] Both soft or fatty pancreases had been identified as risk factors for PF.^[12,50,51] 2. Several articles analyzed the risk factors for PF in patients undergoing PD or distal pancreatectomy. However, the rate of PF in these two different operative techniques are different, PF occurs more frequently following distal pancreatectomy than that following PD.^{[3, 52, 53]} As a result, this heterogeneity in PF rates may impose an unintentional impact on identifying DM as a risk factor for PF or CR-PF. More importantly, identifying the association between DM and PF or CR-PF may help perioperative therapeutic considerations and improve surgical outcomes.

 

Our study has several limitations. First, we did not differentiate DM type (type I, type II and other types), the diagnosis of DM was not standardized. When we categorized the patients, those with mild abnormalities in glucose tolerance were not diagnosed with DM.^[42] Second, this meta-analysis was limited by the availability of observational studies, which may be more prone to confounding factors and bias.^[54] Nevertheless, rigorous inclusion and exclusion criteria as well as the uniform ISGPF definition were applied and study quality was appraised. In our systematic review process, many articles were excluded because of poor definition of PF or inappropriate study design. Third, substantial heterogeneity between studies may preclude a pooled analysis. The preformulated hypothesis and comprehensive search can help to minimize the publication bias. Significant heterogeneity was not observed when we used funnel plots and the Chi-square test and inconsistency (I^?2) statistics. Fourth, as literature search stops on June 2013, works published in the last 9 months are not considered in the meta-analysis. However, after a careful search by our surgical team, few articles about such issue were found in these months. Thus, the articles included in our manuscript were not "out of date".

 

In conclusion, investigations of postoperative PF in patients with preoperative DM who underwent PD or PPPD are rare. The present meta-analysis suggested that preoperative DM is not a risk factor of PF after PD or PPPD. On the contrary, patients without DM might carry a higher risk of PF which may result from fatty or soft pancreas. However, the overall results of the present meta-analysis do not permit any definite conclusions because of the heterogeneity in the definition of DM among different studies. More evidence from prospective randomized clinical trials is needed. 

 

 

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