Safety and outcome of elective synthetic mesh repair for incisional ventral hernias in immunosuppressed patients – a retrospective propensity-score-matched analysis
- Open Access
- 01.12.2025
- Original Article
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Abstract
Introduction
Incisional herniae are a common clinical problem and one of the most frequent long-term complications after abdominal operations with a reported incidence of up to 22.4% three years after midline laparotomy [1]. The incidence increases to more than 30% after midline laparotomy when patients are overweight with a body mass index (BMI) exceeding 27 kg/m² [2]. Also, recent chemotherapy, surgical site infection (SSI), active nicotine consumption, immunosuppression and end colostomy are also associated with increased hernia occurrence [3‐6].
The current standard of treatment is surgical hernia repair including the use of permanent synthetic mesh as reinforcement of the abdominal wall [7]. This method can reduce the risk of recurrent hernias, but may cause serious clinical problems, if SSI occurs [8]. According to the Ventral Hernia Working Group, recurrence and SSI are the main issues in ventral hernia repair [9]. Recurrence rates are described to be up to 20–25% within three years following ventral hernia repair using synthetic mesh [10, 11]. The occurrence of SSI has been observed as a major risk factor for hernia recurrence, that may increase the rate up to 80% [3, 10].
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Prevalence and incidence of patients classified as “immunosuppressed” is likely to increase due to expanding therapeutical options for and a rising population of patients undergoing administration of immunosuppressive agents in autoimmunological, rheumatological and oncological diseases as well as organ transplantation. However, a systematic classification is not available [12‐14]. Simultaneously, immunosuppression is linked to postoperative complications, such as wound healing disorders and SSI, that may lead to mesh resection [15‐18]. The Ventral Hernia Working Group classifies immunosuppressed patients into “Grade 2 - comorbid” in their assessment of risk of SSI, implying increased risk of infection of synthetic material [9]. An analysis of the Americas Hernia Society Quality Collaborative observed more surgical site occurrences but not infections in immunocompromised patients [19]. Further, immunosuppression has been identified as a risk factor for hernia recurrence [20]. A meta-analysis reported 13.5% surgical complications after mesh hernia repair in patients after renal transplantation, while another study found no differences in complications between patients undergoing incisional hernia repair after liver transplantation compared to a control group [21, 22].
This study aimed to determine postoperative outcome of synthetic mesh implantation for ventral hernia repair in immunosuppressed patients in regard to postoperative complications as well as hernia recurrence with focus on the impact of extent of immunosuppression.
Materials and methods
Cohort and inclusion criteria
All patients undergoing ventral hernia repair for incisional herniae between January 2010 and December 2019 at Surgical Department of the Charité – Universitätsmedizin Berlin were included in the analysis. Immunosuppressed patients were defined by (i) taking immunosuppressive drugs with systemic effect or (ii) by the definition of their disease (e.g. Human immunodeficiency virus, HIV). Patients undergoing topical steroid therapy without systemic effects were not classified as immunosuppressed. Patients with oncological disease were only considered immunosuppressed if systemic therapy was administered within four weeks prior to surgery.
Patients were excluded from the analysis if the hernia repair was performed as part of a more complex operation (e.g. (oncological) resection, ostomy reversal surgery, organ (transplant) removal) or emergency cases with signs of incarceration. Patients undergoing sole suture repair were also excluded from the analysis.
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Herniae were mainly diagnosed by general practitioners and then referred to our outpatient clinic, where diagnosis was confirmed by physical examination and ultrasound and/or computed tomography. Surgery was performed in symptomatic patients only.
Clinical data and follow-up
A follow-up via telephone was conducted at 3, 6, 12, 24 and 36 months after surgery by a hernia surgeon for the cohort of immunosuppressed patients. The main objective was to determine rate of recurrent hernias. Follow-up time was determined as time from hernia repair until further abdominal surgery or date of call. Standardized questions using patient-reported outcomes (PROs) as described by Baucom et al. were asked in reference to the follow-up time period: patients were asked (i) if they had experienced symptoms like pain, pressure or discomfort in the area of hernia repair and if (ii) bulging reoccurred [23]. Patients reporting recurrent bulging and/or persistent pain at the original repair site were offered to be examined by a surgeon. Patients declining symptoms were categorized without hernia recurrence.
Data for pre-existing conditions were collected from patients` anamnesis. Diabetes was recorded, if any pharmaceutical therapy was administered.
Further data, including surgical complications were collected from hospital stays, ambulatory visits of the patients in the transplant centers or other contacts with surgeons and physicians at Charité – Universitätsmedizin Berlin. For analysis, surgical complication was recorded, if either of the following occurred in the postoperative course: wound healing disorders, paralytic ileus and events directly linked to surgical intervention (bleeding, injuries). Cardiopulmonary complications included arrythmia with need of observation/treatment in an intensive care unit, prolonged necessity of (non-)invasive ventilation, pulmonary or cardiac embolism as well as pneumonia. Renal complications included acute kidney injury or pyelonephritis. Further, non-surgical site infection (e.g. urinary tract infections), post-operative delirium or other occurrences were recorded. The Clavien-Dindo-Classification was used to categorize surgical complications [24].
Statistical analysis
Data were collected in a prospectively designed database and a propensity score-matching was conducted using the following variables: age, BMI, pre-existing diabetes or nicotine consumption, anticoagulation, risk classification according to the American Society of Anesthesiologists (ASA–score), recurrent hernia, classification of incisional abdominal wall herniae according to the European Hernia Society (EHS) and surgical approach (laparoscopic vs. open) [25, 26]. A match tolerance of 0.1 was acknowledged.
To enable comparative group analysis, following parameters were dichotomized: age (≤ 59.9 vs. > 60 years), BMI (≤ 29.9 vs. > 30 kg/m²) as well as duration of operation (≤ 120 vs. > 120 min) [27, 28].
Classification and regression tree (CART) analysis using Chi-squared Automatic Interaction Detection approach was conducted to evaluate impact of parameters on complications after hernia repair. Minimum of cases for upper and lower nodes were defined as 50 and 25, respectively.
All analyses were performed using Statistical Product and Service Solutions (SPSS), version 29 (IBM, USA). Variables are described as numbers with percentages as appropriate, or as means ± standard deviation (SD). The Chi square test (χ2) was used for analysis of categorical variables, and Student’s t test for numerical variables. Parameters, that revealed statistical significance in univariate analysis were included in multivariate analysis. Here, a logistic regression model, including demographic and operative parameters, was used to assess risk factors for postoperative complications. Hazard Ratio (HR) with Confidence interval (CI) were calculated. A p-value of < 0.05 was considered statistically significant.
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The Strengthening the Reporting of Observational Studies in Epidemiology (STROBE) guidelines were used in this study´s design [29].
This study was conducted according to the guidelines of the Declaration of Helsinki and was approved by the local ethics committee of Charité Universitätsmedizin Berlin (EA1/067/20).
Results
Overall cohort characteristics and outcome
Out of 732 patients that underwent elective surgery between 2010 and 2019 because of incisional abdominal wall hernia at our institution, a total of n = 163 (22.3%) patients were classified as immunosuppressed, see Fig. 1. The mean age of the overall cohort was 58.7 (± 12.5) years and most patients were classified as ASA 1 or 2 (n = 347; 47.4%). Using the EHS classification, the majority of herniae was classified as “midline” (n = 555;75.8%) and W2 or W3 (n = 650; 88.8%). 119 (16.3%) patients were operated due to recurrent hernia. Open hernia repair was conducted in 454 (62.0%) patients and sublay (n = 348; 47.5) was performed most frequently, followed by intraperitoneal onlay mesh (IPOM, n = 307; 41.0%).The mean duration of surgery was 149.3 (± 82.7) minutes. Detailed characteristics of the overall cohort are displayed in Table 1.
Fig. 1
Formation of the Cohort and Subgroups. ASA - American Society of Anesthesiologists; BMI - Body Mass Index; EHS - European Hernia Society
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Table 1
Overall cohort characteristics
Overall cohort n = 732 | Patients with immunosuppression n = 163 | |
|---|---|---|
Age in years; | 58.7 ± 12.5 | 55.5 ± 10.9 |
BMI in kg/m2, | 27.4 ± 7.8 | 26.6 ± 6.5 |
ASA | ||
1/2 3/4 Missing | 347 (47.4) 251 (34.3) 134 (18.3) | 53 (32.5) 82 (50.3) 28 (17.2) |
COPD | 75 (10.2) | 16 (9.8) |
Diabetes | 132 (18.0) | 52 (31.9) |
Active nicotine consumption | 112 (15.3) | 13 (8.0) |
Oncologic disease | 267 (36.5) | 46 (28.2) |
Reason for IS | ||
Solid OT LT KT Other IBD Rheumatological HIV | - | 150 (92.0) 98 (60.1) 37 (22.7) 15 (9.2) 4 (2.5) 6 (3.7) 3 (1.8) |
Recurrent Hernia | 119 (16.3) | 24 (14.7) |
Hernia Size in cm | ||
Length Width | 9.9 ± 6.6 9.3 ± 6.3 | 11.2 ± 7.8 10.2 ± 7.1 |
EHS | ||
Midline (M1-5) Lateral (L1-4) | 555 (75.8) 177 (24.2) | 109 (66.9) 54 (33.1) |
EHS | ||
W1 W2 W3 | 82 (11.2) 330 (45.1) 320 (43.7) | 13 (8.0) 73 (44.8) 77 (47.2) |
Surgical approach | ||
Open Laparoscopic | 454 (62.0) 278 (38.0) | 89 (54.6) 74 (45.4) |
Type of Repair | ||
Onlay Sublay IPOM Other | 40 (5.5) 348 (47.5) 307 (41.9) 37 (5.1) | 9 (5.5) 69 (42.3) 80 (49.1) 5 (3.1) |
Duration of surgery in minutes | 149.3 ± 82.7 | 157.1 ± 74.1 |
Follow-up completion (%) | - | 155 (95.1%) |
Months after surgery ≥ 12 months ≥ 24 months ≥ 36 months | - - - - | 26.8 (± 20.0) 120 (73.6) 70 (42.9) 52 (31.9) |
Postoperative complications occurred in 166 (22.7%) patients, and here, the majority was classified as Clavien-Dindo grade ≤ IIIa (n = 137; 18.7%). SSI were the most common surgical postoperative complication (n = 35; 4.8%). The mean duration of hospitalization was 8.6 (± 11.1) days, see also Table 2.
Parameters associated with complications in the overall cohort
Univariate analysis revealed age (> 60 years) and patients classified as ASA 3/4 but not BMI as variables significantly associated with complications (p < 0.001, p < 0.001 and p = 0.49 respectively). Analyzing specific comorbidities, preexisting chronic obstructive pulmonary disease (COPD), diabetes and immunosuppression also showed significant impact on incidence of postoperative complications (p < 0.001, p = 0.04 and p = 0.036, respectively). Using EHS classification for ventral incision hernia, only larger width but not location reached statistically significant impact on complications (p = 0.003 and p = 0.99, respectively). Further, duration of surgery exceeding 120 min was associated with increased occurrence of postoperative complications (p < 0.001). Supplement Table 1 displays detailed information of the univariate analysis.
In multivariate analysis, only age > 60 years, COPD and duration of surgery > 120 min showed persistent statistically significant impact (p = 0.002, p = 0.032 and p < 0.001, respectively), see also Supplement Table 2.
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CART analysis revealed duration of operation as most impactful variable for occurrence of postoperative complications in the overall cohort, followed by comorbidities. In the subset of patients where operation was under 120 min, diabetes was most relevant, while COPD showed most important influence in patients, where operation time was > 120 min. Immunosuppression did not show significant impact in this analysis, see also Fig. 2a.
Fig. 2
Classification and regression tree (CART)-analysis on impact of clinical variables on occurence of postoperative complications after incisional ventral hernia repair using mesh. To investigate and rank the relevance of clinical variables with putative influence on postoperative complications, CART method was used. Regression tree classified patients in this study for their associated variables in regard of occurrence of postoperative complications. Nodes indicate parameters that significantly improve correct classification and hereby decrease impurity toward the terminal (upper) nodes. Variables with statistically significant impact in univariate analysis were implemented. (a) In the overall cohort, duration of operation showed most relevant impact, and in the subgroup of patients operated < 120 min, diabetes mellitus was of importance, while combination of COPD and prolonged length of operation led to increase of postoperative complication. (b) In the cohort of immunosuppressed patients, the number of immunosuppressive agents was of most meaningful impact. Here, in patients with up to two agents, increased age was next-ranking factor, while history of immunosuppression exceeding four years was of relevance in patients with more than two different pharmaceuticals
Characteristics and outcome of immunosuppressed patients
The mean age of patients classified as immunosuppressed was 55.5 (± 10.9) years and most patients were classified with higher ASA gradings of 3 and 4 (n = 82; 50.3%). Preexisting diabetes was reported in 52 (31.9%) of patients. Immunosuppression was mainly caused by pharmacological therapy due to rejection prophylaxis for solid organ transplantation (n = 150; 92.0%). Here, most patients were recorded with a medical history of liver transplantation (n = 98; 60.1%). Similar to the overall cohort, midline herniae (n = 109; 66.8%) with larger width of W2/W3 (n = 150; 92.0%) were most prominent. Laparoscopic approach was performed in 74 (45.4%) patients and hernia repair using IPOM technique was most frequent (n = 80; 49.1%), see also Table 1.
Overall, complications in this cohort were observed in 47 (28.8%) patients and here, SSI were diagnosed in 12 (7.4%) of patients. Complications exceeding Clavien-Dindo IIIa were found in 14 (8.6%) patients while mean hospitalization was 9.3 (± 10.7) days. Details on complications in immunosuppressed patients are displayed in Table 2.
Table 2
Early postoperative outcome
Overall cohort n = 732 | Patients with immunosuppression n = 163 | |
|---|---|---|
Patients with postoperative complications | 166 (22.7) | 47 (28.8) |
Patients with postoperative surgical complications | 109 (14.9) | 24 (14.7) |
Typ of complications* | ||
SSI Seroma Bleeding/hematoma Paralytic Ileus Renal Cardiopulmonary Other | 35 (4.8) 30 (4.1) 12 (1.6) 8 (1.1) 21 (2.9) 27 (3.7) 80 (10.9) | 12 (7.4) 7 (4.3) 1 (0.6) 0 (0) 7 (4.3) 7 (4.3) 31 (19.0) |
Grade of complication (Clavien-Dindo) | ||
≤IIIa ≥IIIb | 137 (18.7) 29 (4.0) | 33 (20.2) 14 (8.6) |
Length of Hospital stay in days | 8.6 ± 11.1 | 9.3 ± 10.7 |
Parameters associated with complications in immunosuppressed patients
In the cohort of immunosuppressed patients, only patients aged > 60 years, patients under therapy with more than two immunosuppressive agents and duration of immunosuppressive therapy beyond 48 months were associated with statistically significant increased rate of complications (p = 0.035, p = 0.003 and p = 0.018), see Table 3.
Table 3
Univariate analysis of impact of clinical variables associated with postoperative complications in immunosuppressed patients
variable | Patients with postoperative complications (%) | p value |
|---|---|---|
Age | ||
< 60 years ≥ 60 years | 22 (22.7) 25 (37.9) | 0.035 |
BMI | ||
< 30 kg/m² > 30 kg/m² | 32 (28.3) 13 (28.3) | 0.994 |
ASA | ||
1/2 3/4 | 13 (24.5) 25 (30.5) | 0.452 |
Comorbidities | ||
COPD Active nicotine consumption Diabetes Oncologic disease | 7 (43.8) 5 (38.5) 19 (36.5) 12 (26.1) | 0.165 0.424 0.137 0.627 |
EHS | ||
Midline (M1-5) Lateral (L1-4) | 32 (29.4) 15 (27.8) | 0.834 |
EHS | ||
W1 W2 W3 | 2 (15.4) 18 (24.7) 27 (35.1) | 0.20 |
Surgical approach | ||
Open Laparoscopic | 25 (28.1) 22 (29.7) | 0.818 |
Duration of surgery | ||
< 120 min > 120 min | 17 (27.0) 30 (30.0) | 0.679 |
Reason for immunosuppression | ||
LT KT Other OT IBD Rheumatological HIV | 28 (28.6) 13 (35.1) 3 (20.0) 3 (50.0) 0 (0) 0 (0) | 0.365 |
Class of immunosuppressive agent | ||
CNI Steroids MMF Antibodies Other | 44 (29.7) 19 (33.9) 17 (27.4) 3 (37.5) 8 (29.6) | 0.428 0.299 0.755 0.579 0.920 |
Number of immunosuppressive agents | ||
≤ 2 > 2 | 23 (21.3) 24 (43.6) | 0.003 |
Duration of immunosuppression | ||
> 12 months > 24 months > 36 months > 48 months | 34 (28.1) 25 (31.3) 23 (35.9) 20 (40.8) | 0.820 0.409 0.076 0.018 |
Multivariate analysis implementing these parameters verified statistical significant association for “age” (HR 0.45, 95%CI 0.21–0.97, p = 0.042), “number of immunosuppressive agents” (HR 0.41, 95%CI 0.19–0.89, p = 0.023) and “duration of immunosuppression” (HR 0.42, 95%CI 0.19–0.92,p = 0.03), see Table 4.
Table 4
Multivariate logistic regression of parameters associated with postoperative complications in immunosuppressed patients undergoing incision hernia repair
Variable | n | Hazard Ratio | 95% CI | p value | |
|---|---|---|---|---|---|
lower | upper | ||||
Age (< 60* vs. ≥60 years) | 144 | 0.446 | 0.205 | 0.972 | 0.042 |
Number of immunosuppressive agents ≤ 2* vs. >2 | 144 | 0.406 | 0.186 | 0.885 | 0.023 |
Duration of immunosuppression ≤ 48* vs. > 48 months | 144 | 0.422 | 0.193 | 0.922 | 0.03 |
CART analysis identified the number of immunosuppressive agents with most relevance regarding postoperative complications. Patients´ age was most impactful in the subset of patients with up to two immunosuppressive agents and duration of immunosuppression in patients with more than two immunosuppressant, see Fig. 2b.
Parameters associated with hernia recurrence in immunosuppressed patients
Follow-up was available in 155 (95.1%) of patients and mean follow-up was 26.8 (± 20.0) months after hernia repair. During this period, 32 (19.6%) patients reported pain and/or bulging. All of these patients were eventually examined by a surgeon and recurrent hernia was observed in 23 (14.1%) patients, resulting in a specificity of PROs of 71.8%.
Univariate analysis revealed increased rate of recurrence in patients younger than 60 years and in midline herniae (p = 0.045 and p = 0.012, respectively). Further, laparoscopic approach and duration of operation > 120 min were found with statistically significant impact (p = 0.036 and p = 0.023, respectively). A statistically significant, twofold increase of recurrent herniae was observed in patients with more than two immunosuppressive agents (p = 0.049). For details see Table 5.
Table 5
Univariate analysis on impact of clinical parameters on recurrence of hernia in immunosuppressed patients
Variable | Recurrence in Patients with immunosuppression n = 163 | p value |
|---|---|---|
Age | ||
< 60 years ≥ 60 years | 18 (19.6) 5 (7.9) | 0.045 |
BMI | ||
< 30 kg/m² > 30 kg/m² | 15 (14.2) 8 (17.8) | 0.571 |
ASA | ||
1/2 3/4 | 9 (17.6) 11 (14.5) | 0.630 |
Comorbidities | ||
COPD Active nicotine consumption Diabetes Oncologic disease | 4 (25.0) 1 (7.7) 8 (15.7) 4 (9.3) | 0.227 0.449 0.835 0.230 |
Recurrence after prior hernia reparation | 4 (16.7) | 0.813 |
EHS | ||
Midline (M1-5) Lateral (L1-4) | 21 (19.6) 2 (4.2) | 0.012 |
EHS | ||
W1 W2 W3 | 0 (0) 9 (13.2) 14 (18.9) | 0.185 |
Surgical approach | ||
Open Laparoscopic | 8 (9.4) 15 (21.4) | 0.036 |
Duration of surgery | ||
< 120 min > 120 min | 4 (6.7) 19 (20.0) | 0.023 |
Reason for Immunosuppression | ||
LT KT Other OT IBD Rheumatological HIV | 17 (18.3) 2 (5.9) 4 (26.7) 0 (0.0) 0 (0) 0 (0) | 0.224 |
Class of Immunosuppressive Agent | ||
CNI Steroids MMF Antibodies Other | 23 (16.4) 8 (15.1) 9 (15.5) 0 (0) 6 (24.0) | 0.089 0.949 0.854 0.225 0.159 |
Number of Immunosuppressive Agents | ||
≤ 2 > 2 | 11 (10.8) 12 (22.6) | 0.049 |
Duration of Immunosuppression | ||
> 12 months > 24 months > 36 months > 48 months | 5 (23.8) 10 (16.7) 11 (14.9) 14 (15.7) | 0.200 0.566 0.954 0.643 |
Outcome after ventral incisional hernia repair after propensity score matching
After propensity score matching using eight clinical variables, n = 113 patients with ongoing immunosuppression (group IS) were compared to n = 113 patients without (group nIS), see Fig. 1; Table 6. Overall complications did not differ between groups (n = 31/27.4% vs. n = 31/27.4%; p = 0.88). Surgical complications were significantly more frequent in the control group (nIS; n = 24/21.2% vs. IS; n = 15 (13.3%), p = 0.02). Conversely, increased renal complications were observed in the IS group (IS; n = 8/7.1% vs. nIS; n = 2/1.8%, p = 0.05). see Table 7. All patients with renal complications had undergone organ transplantation (liver transplantation: n = 4, kidney transplantation: n = 2, combined kidney/pancreas transplantation: n = 2).
Table 6
Group characteristics and univariate analysis after propensity score matching
Immunosuppression (Group IS) n = 113 | No Immunosuppression (Group nIS) n = 113 | p-value | |
|---|---|---|---|
Age* in years; | 57.1 ± 10.3 | 56.0 ± 13.7 | 0.49 |
BMI* in kg/m2, | 26.6 ± 7.3 | 26.7 ± 10.4 | 0.89 |
ASA* | 0.42 | ||
< 3 ≥ 3 | 71 (62.8) 42 (37.2) | 65 (57.5) 48 (42.5) | |
COPD | 12 (8.0) | 9 (10.6) | 0.49 |
Diabetes* | 32 (28.3) | 25 (22.1) | 0.28 |
Active nicotine consumption* | 11 (9.7) | 11 (9.7) | 1.0 |
Oncologic disease | 34 (30.1) | 36 (31.9) | 0.77 |
Reason for IS | 101 (89.4) | - | - |
Solid OT LT KT Other IBD Rheumatological HIV | 66 (58.4) 25 (22.1) 10 (8.8) 4 (3.5) 5 (4.4) 3 (2.7) | ||
Recurrent Hernia* | 17 (15.0) | 17 (15.0) | 1.000 |
Hernia Size in cm | |||
Length Width | 10.9 ± 7.5 9.8 ± 6.2 | 9.5 ± 5.6 9.7 ± 6.3 | 0.13 0.90 |
EHS* | 0.64 | ||
Midline (M1-5) Lateral (L1-4) | 84 (74.3) 29 (25.7) | 87 (77.0) 26 (23.0) | |
EHS* | |||
W1 W2 W3 | 8 (7.1) 51 (45.1) 54 (47.8) | 9 (8.0) 51 (45.1) 53 (46.9) | 0.97 |
Surgical approach | |||
Open Laparoscopic | 60 (53.1) 53 (46.9) | 61 (54.0) 52 (46.0) | 0.89 |
Type of Repair | |||
Onlay Sublay IPOM Other | 4 (3.5) 46 (40.7) 60 (53.1) 3 (2.7) | 7 (6.2) 42 (37.2) 56 (49.6) 8 (7.0) | 0.59 |
Duration of surgery in minutes | 149.9 ± 65.8 | 163.3 ± 105.5 | 0.25 |
Table 7
Comparison of early postoperative outcome in patients with and without immunosuppression after propensity score matching
Immunosuppression (Group IS) n = 113 | No Immunosuppression (Group nIS) n = 113 | p value | |
|---|---|---|---|
Patients with postoperative complications | 31 (27.4) | 31 (27.4) | 0.88 |
Patients with postoperative surgical complication | 15 (13.3) | 24 (21.2) | 0.02 |
Typ of complications* | |||
SSI Seroma Bleeding/hematoma Paralytic Ileus Renal Cardiopulmonary Other | 5 (4.4) 9 (8.0) 1 (0.9) 0 (0.0) 8 (7.1) 5 (4.4) 21 (18.6) | 9 (8.0) 9 (8.0) 1 (0.9) 3 (2.7) 2 (1.8) 7 (6.2) 17 (15.0) | 0.27 0.27 1.0 0.08 0.05 0.55 0.7 |
CDC Grade of complication | |||
≤IIIa ≥IIIb | 20 (17.7) 12 (10.6) | 23 (20.3) 8 (7.1) | 0.32 |
Length of Hospital stay in days | 9.7 ± 11.8 | 8.6 ± 10.4 | 0.46 |
Discussion
This retrospective study aimed to investigate safety and long-term outcome of mesh-implantation for incisional hernia repair in immunosuppressed patients.
Variables associated with occurrence of postoperative complications in the overall cohort were common clinical parameters such as age and comorbidities (COPD, diabetes, nicotine consumption) [30‐32]. However, in this cohort, BMI was not associated with postoperative complications. Length of surgery over 120 min and EHS width showed statistically significant impact on occurrence of postoperative complication, as has been reported in a recent meta-analysis and a large cohort study, respectively [27, 33]. In multivariate analysis of these parameters, age, COPD and duration of surgery showed statistical significance. A statistical impact of immunosuppression on postoperative complications was only observed in univariate analysis, but not in multivariate analysis.
We applied CART analysis to stratify variables for impact on postoperative complications. Interestingly, length of operation was associated with highest impact on occurrence of complications and here, longer operations in combination with preexisting pulmonary disease was relevant. This reflects routine clinical experience in surgery; anesthesia duration exceeding 2.5 h has been associated with a three-fold risk of postoperative pulmonary complications [34].
After propensity score matching, overall complications did not differ between patients with and without immunosuppression. This observation comes in line with recent cohort reports, but opposing findings also exist [19, 20, 35].
In this study, immunosuppressive therapy increased the risk of specific postoperative complications e.g. renal dysfunction when compared to the non-immunocompromised cohort. All of these patients had received organ transplantation and this collective is known to suffer of various comorbidities while at the same time those comorbidities are risk factors for complications after abdominal and other surgical interventions [9, 36‐38]. In the cohort of immunosuppressed patients, elderly patients were associated with an elevated risk for complications after operation. However, no other comorbidity reached statistically significant impact, which might be explained due to relatively low numbers. Number of immunosuppressive agents above two and duration of immunosuppressive status over four years revealed negative impact within this cohort and maintained statistical relevance in multivariate analysis. Correspondingly, CART analysis identified the amount of immunosuppressants as most relevant factor for postoperative complications. As mentioned before, effects of immunosuppression on surgical procedures are widely known as well as the immunosuppressive effect of surgery itself [16, 18, 39‐41]. We did not find a previous study to report on the association of the number of administered immunosuppressants and complications, however, we did not assess dosage or trough levels. Recommendations of perioperative handling of immunotherapy remain inconclusive with only poor data and recent guidelines of the World Health Organization for SSI prevention therefore recommend no alteration in the perioperative setting [42]. Our data certainly support this statement.
However, as more than two simultaneously administered immunosuppressants resulted in a significant increase in postoperative complications, a potential benefit might be achieved for a subset of patients when the number of immunosuppressants is reduced in the perioperative setting rather than a dosage reduction. Of interest, combination of immunosuppressants have been observed to amplify their effects: caIcineurin inhibitors might increase immunosuppressive function of steroids and triple immunosuppressive therapy has been reported to affect cytokine profiles beyond the individual drug´s capacity [43, 44].
Still, the choice of substances that might be prone to be paused remains to be evaluated. In LT patients, the phenomenon of tolerance is known, potentially enabling the strategy of pausing the immunosuppression in the perioperative, elective setting. Especially elderly patients might benefit from this [45‐47].
Cumulative mesh-infection rate after hernia repair is reported to be up to 8% and recurrence rate of hernia after using mesh is still up to 30% after 10 years [11, 48]. Recurrence rate in immunosuppressed patients in this study was 14% with a mean follow up of two years. Evaluation of hernia recurrence was therefore limited. Still, our data suggest no detriment for immunosuppressed patients, as estimated recurrence rates of more than 12% have been reported after 2 years [7]. Younger patients were associated with higher rate of recurrence in the group of immunocompromised patients, which is contradictory to other reports [49‐51]. However, a study reporting on on a US database with over 30,000 patients found no age-dependency in ventral hernia repair using mesh and a study based on the Herniamed-Registry found less recurrences in patients > 80 years old [35, 52].
In this study, a laparoscopic approach for incisional hernia repair was associated with increased hernia recurrence in the cohort of immunosuppressed patients. In general, laparoscopic hernia repair has been shown to be equal to open approaches regarding postoperative outcome with benefits in pain, mobilization and length of hospital stay. However, it is mainly recommended in hernia size up to 10 cm maximum [11, 53, 54]. In our cohort, most immunosuppressed patients presented with herniae > 10 cm combined with higher classification in ASA-grading. Thus, the surgical approach might have been influenced by overall morbidity towards minimal-invasive technique, but with the concomitant elevated risk of hernia recurrence. The inferior outcome after laparoscopic hernia repair in our cohort therefore might reflect the complexity of patients´ medical history and should not be generalized.
Of importance, duration of surgery exceeding 120 min and intake of more than two immunosuppressant at time of surgery were associated with increased recurrence of hernia, highlighting the importance of these aspects in this cohort.
Certain limitations of this study have to be addressed. Given its retrospective, single-center character, multiple potential bias might occur. In the setting of a retrospective, exploratory analysis in a large cohort, some findings might be sole statistical phenomena and clinical experience and day-to-day care might not reflect these observation. However, propensity score matching allowed for correction between groups. Thus, certain findings from the overall should be interpreted with the findings from the propensity score matching.
As classification of “immunosuppressed” remains vague due to lack of a coherent definition, some aspects may have been overlooked. Of note, diabetes or an underlying oncological disease/history of disease is sometimes considered as immunosuppressive [55, 56]. Further, we did not assess dosage or serum levels of immunosuppression or reason for combination of immunosuppressants. While increased dosage might hamper e.g. wound healing, most immunosuppressants in this context are trough-level based with focus on rejection prophylaxis in an individualized manner. The clinical concepts or reasonings for multi-drug combinations were not assessed in this analysis.
Conclusion
In this study, incisional hernia repair using mesh proved safe in immunosuppressed patients without increased adverse surgical outcome, especially without increase of SSI. Number of immunosuppressants administered and a longer history of immunosuppression however may increase overall postoperative complications in a subset of patients. To the best of our knowledge, this is the first systematical evaluation of safety of mesh implantation for hernia surgery in immunosuppressed patients with important insight into its feasibility. Still, optimal handling and risks of immunosuppression in surgery and especially hernia repair using allogenic material remain obscure and require further research, preferably in randomized controlled trials.
Declarations
Conflict of interest
The authors have no conflict of interest to disclose.
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