ABSTRACT
Background
Anti‐adhesion barriers are effective in reducing adhesion formation, but their impact on preventing adhesive bowel obstruction remains unclear. This study aimed to evaluate the effectiveness of anti‐adhesion barriers in preventing adhesive bowel obstruction using a nationwide medical database in Japan.
Method
Surgical cases for abdominal gastroenterological cancers were categorized into six categories based on procedure type (Open or Laparoscopic) and target organ (Stomach, Colorectum, and Hepatobiliary‐pancreas). Patients were classified into an anti‐adhesion barriers group (treatment) or a non‐anti‐adhesion barriers group (comparison). Propensity score matching was performed to balance baseline characteristics. Survival analysis with hospitalizations due to adhesive bowel obstruction as the outcome was conducted, and hazard ratios (HR) were calculated using univariate Cox regression analysis.
Results
A total of 163 194 cases were analyzed. In the Open Colorectum and Laparoscopic Colorectum categories, the cumulative incidence curve for the treatment group was lower than that of the comparison group (Log‐rank test; Open Colorectum: p < 0.01, Laparoscopic Colorectum: p = 0.01). The HR was significantly lower in both categories (Open Colorectum: 0.87 [95% CI: 0.80–0.95], Laparoscopic Colorectum: 0.84 [95% CI: 0.73–0.96]). In other categories, no significant differences were found between the two groups. [Correction added on 2 February 2026, after first online publication: The p values of Open Colorectum and Laparoscopic Colorectum have been corrected.]
Conclusion
This study suggests that anti‐adhesion barriers use could effectively reduce the risk of adhesive bowel obstruction in Open Colorectum and Laparoscopic Colorectum surgeries, but not in Open Stomach, Open Hepatobiliary‐pancreas, or Laparoscopic Stomach surgeries. Further research is needed to confirm these findings and explore broader applications.
Keywords: abdominal gastroenterological cancers, anti‐adhesion barriers, disease‐free survival analysis, postoperative adhesive bowel obstruction, propensity score matching
We performed a survival analysis of abdominal gastroenterological cancer surgery cases with and without anti‐adhesive barriers, with the development of adhesive bowel obstruction as the outcome. The incidence of adhesive bowel obstruction was significantly lower in patients undergoing open or laparoscopic colorectal surgery in the anti‐adhesive barriers group.
1. Introduction
Adhesive bowel obstruction is a serious complication in abdominal surgery and remains a major clinical concern. Postoperative adhesive bowel obstruction occurs in approximately 10% of patients following colon surgery, leading to substantial healthcare costs and morbidity [1]. This condition can sometimes necessitate invasive treatments, resulting in further risks to patients [2]. To prevent postoperative adhesions that cause adhesive bowel obstruction, anti‐adhesive barriers are used in clinical practice [3, 4].
Numerous studies have been reported to investigate the effectiveness of anti‐adhesion barriers in preventing adhesive bowel obstruction, but the results have been inconsistent. Although anti‐adhesion barriers have demonstrated efficacy in reducing postoperative adhesion formation itself that could cause various adverse events (organ damage during subsequent surgeries, infertility, chronic pelvic pain, and adhesive bowel obstruction), their impact on preventing adhesive bowel obstruction remains inconsistent [5, 6]. Several randomized controlled trials and systematic reviews have assessed the effectiveness of anti‐adhesion barriers in preventing adhesive bowel obstruction [7, 8, 9, 10, 11]. Even after the publication of systematic reviews, subsequent studies, including recent large‐scale database analyses, have reported conflicting results [12, 13, 14, 15, 16]. Moreover, the timing of adhesive bowel obstruction occurrence varies widely, and the observation periods in previous studies have been inconsistent, making it difficult to determine the temporal trends of adhesive bowel obstruction development [17].
The aim of the study is to evaluate the effectiveness of anti‐adhesion barriers in preventing adhesive bowel obstruction. Using a nationwide medical database, we collected gastroenterological cancer surgery cases and categorized them by operative procedure and organ. We classified the cases into two groups based on whether anti‐adhesion barriers were used during surgery and conducted a survival analysis to assess the impact of anti‐adhesion barriers use on the prevention of adhesive bowel obstruction.
2. Methods
2.1. Data Source
We utilized the Diagnosis Procedure Combination (DPC) database maintained by the research group funded by Japan's Ministry of Health, Labour and Welfare. Participating hospitals voluntarily provide data to this group annually. In 2016, approximately 1200 hospitals contributed to this database [18].
The DPC database comprises several files. Form 1 contains discharge summaries, including disease names (the primary disease, the trigger disease, the most and second‐most medical‐resource‐intensive disease, and comorbidities coded based on the International Classification of Diseases 10th Revision (ICD‐10)), patient demographics (age, sex, height, and weight), admission and discharge dates, and surgical details. Surgical details are recoded using a schedule code consisting of one alphabetic character followed by three to five Arabic numerals or Japanese characters.
Files E and F contain information on medical procedures and medications administered during hospitalization, including dates and quantities. Each medical procedure and medication is coded using a claim code consisting of nine Arabic numerals. These codes enable case selection and identification of medical services provided.
2.2. The Study Population
The target population for this study consisted of patients who underwent abdominal gastroenterological cancer surgery. To ensure data consistency, we restricted the analysis to institutions that provided data throughout the observation period uninterruptedly.
Inclusion criteria were defined based on the study population. We included cases in which primary abdominal gastroenterological cancer surgeries (stomach, small bowel, colon, rectum, anus, liver, bile duct, and pancreas) were performed between April 2011 and March 2016. These cases were identified by the registration of the gastroenterological cancer ICD‐10 code under the most medical‐resource‐intensive disease category, along with the corresponding gastroenterological cancer surgery codes (Tables S1 and S2).
Exclusion criteria comprised cases with missing data and those involving reoperation after the primary surgery. Reoperations were defined as surgeries performed to treat complications arising from the initial abdominal gastroenterological cancer surgery. Cases meeting these criteria were classified as reoperation cases and excluded from the analysis.
2.3. Categorizing the Study Population
We categorized the study population into six categories based on the surgical procedure and the target organ. Previous studies have reported that the type of surgical approach—open versus laparoscopic—significantly influences the occurrence of adhesive bowel obstruction [19]. Additionally, prior clinical studies on similar topics have often focused on specific target organs. Considering these factors, we determined that analyzing the data separately by surgical procedure and organ would be appropriate.
The study population was categorized according to the type of surgery (Open or Laparoscopic) and the target organ:
Stomach
Colorectum (including small bowel, colon, rectum, and anus)
Hepatobiliary‐pancreas (including liver, bile duct, and pancreas)
2.4. Treatment
We classified the study population in each category into two groups based on the use of sheet‐type anti‐adhesion barriers. Cases in which the claim code “730840000” (indicating sheet‐type synthetic anti‐adhesion barriers) was registered on the date of surgery were assigned to the group using anti‐adhesion barriers (treatment group). All other cases were assigned to the group not using anti‐adhesion barriers (comparison group). During the observation period, two types of sheet‐type anti‐adhesion barriers were covered by the national health insurance in Japan. Although these products differ in their characteristics and mechanisms of adhesion prevention, they share the same clinical purpose—prevention of postoperative adhesion formation. Therefore, we treated them as a single category in this study.
2.5. Statistical Analysis
We conducted a survival analysis with adhesive bowel obstruction as the primary outcome. Outcomes were defined by identifying hospitalizations in which an ICD‐10 code corresponding to adhesive bowel obstruction was registered in the most medical‐resource‐intensive disease, the primary disease, or the trigger disease. The relevant ICD‐10 codes included as follows:
K56.5: bowel adhesion with obstruction
K56.6: Other and unspecified bowel obstruction
K56.7: undetailed ileus
K91.3: postoperative bowel obstruction
Follow‐up was confirmed through the presence of outpatient visit or hospitalization records, with a maximum observation period of 60 months postoperatively. Termination criteria included as follows:
Interruption of outpatient visits or hospitalization records for more than 1 year
Abdominal surgery unrelated to bowel obstruction
Death
Data were combined and tracked using hospital and patient codes from the DPC database Form 1.
We performed propensity score (PS) matching and analyzed the matched cohort to balance covariates between the treatment and comparison groups [20]. PS were calculated using a logistic regression model, incorporating covariates possibly associated with treatment or outcomes, which were extracted from the database. The covariates included as follows:
Patient demographics: age, sex, and body mass index (BMI)
Comorbidities: hypertension, arrhythmia, chronic heart failure, ischemic heart disease, diabetes, chronic obstructive pulmonary disease (COPD), asthma, and cerebrovascular disease
Medications: antithrombotic and steroid use
Other factors: maintenance hemodialysis, cancer stage, high‐volume center, and general anesthesia time
High‐volume centers were defined based on previous studies, as no clear standard definition exists [21]. For this study, we defined a high‐volume center as a facility that performs at least:
30 stomach surgeries per year
50 colorectal surgeries per year
30 hepatobiliary‐pancreatic surgeries per year
We performed 1:1 nearest neighbor PS matching with a maximum caliper width of 0.1 of the standardized deviation of the logit of the PS. Covariate balance between the two groups was assessed using the absolute standardized difference (ASD) in both the pre‐matched and matched cohorts [22].
After obtaining the matched cohort, we evaluated the effectiveness of the treatment using survival analysis. Cumulative incidence curves were constructed with hospitalization due to adhesive bowel obstruction as the outcome, and the log‐rank test was performed to assess differences between the two groups. Proportional hazards between the groups were verified using a log‐minus‐log plot. An adjusted hazard ratio (HR) and its 95% confidence interval (95% CI) were calculated using univariate Cox regression analysis.
All analyses were conducted using R version 4.2.1 (R Foundation for Statistical Computing, Vienna, Austria) with packages “MatchIt”, “survival”, and “survminer”.
3. Results
3.1. Characteristics of the Study Cohort
We collected cases from 296 hospitals. During the study period, 178 073 cases met the inclusion criteria. After excluding 14 879 cases based on the exclusion criteria, 163 194 cases were included in the study population (Figure 1).
Open Stomach: 31 499 cases (comparison group: 14 155; treatment group: 17 344).
Open Colorectum: 40 016 cases (comparison group: 20 149; treatment group: 19 867).
Open Hepatobiliary‐pancreas: 22 421 cases (comparison group: 13 876; treatment group: 8545).
Laparoscopic Stomach: 20 438 cases (comparison group: 17 399; treatment group: 3039).
Laparoscopic Colorectum: 48 357 cases (comparison group: 35 328; treatment group: 13 029).
Laparoscopic Hepatobiliary‐pancreas: 463 cases (comparison group: 361; treatment group: 102).
FIGURE 1.
Flowchart for the study population selection process.
Baseline demographic and clinical characteristics for the overall cohort and each category are presented in Table 1.
TABLE 1.
Baseline demographics and clinical characteristics of all study population and each category.
| All | Open Stomach | Open Colorectum | Open Hepatobiliary‐pancreas | Laparoscopic Stomach | Laparoscopic Colorectum | Laparoscopic Hepatobiliary‐pancreas | |
|---|---|---|---|---|---|---|---|
| n = 163 194 | n = 31 499 | n = 40 016 | n = 22 421 | n = 20 438 | n = 48 357 | n = 463 | |
| Demographics | |||||||
| Age (mean (SD)) | 69.6 (11) | 70.6 (10.6) | 71.1 (11.4) | 69.5 (9.7) | 67.6 (11.1) | 68.7 (11.3) | 69.2 (10) |
| Male (%) | 99 779 (61.1) | 22 008 (69.9) | 22 360 (55.9) | 14 338 (63.9) | 13 508 (66.1) | 27 223 (56.3) | 342 (73.9) |
| Height (cm) (mean (SD)) | 159.3 (9.4) | 159.9 (9.2) | 158 (9.7) | 159.7 (9.3) | 160.7 (9.1) | 159.2 (9.4) | 160.9 (8.4) |
| Weight (kg) (mean (SD)) | 57.3 (11.7) | 56.9 (11.4) | 55.5 (11.9) | 57.7 (11.1) | 58.7 (11.2) | 58.1 (11.7) | 62.3 (24) |
| BMI (mean (SD)) | 22.5 (3.6) | 22.2 (3.5) | 22.1 (3.7) | 22.5 (3.4) | 22.6 (3.3) | 22.8 (3.5) | 24 (9.7) |
| Medical history | |||||||
| Hypertension (%) | 36 925 (22.6) | 7077 (22.5) | 9014 (22.5) | 5945 (26.5) | 4139 (20.3) | 10 639 (22.0) | 111 (24.0) |
| Arrhythmia (%) | 6803 (4.2) | 1401 (4.4) | 1665 (4.2) | 1024 (4.6) | 729 (3.6) | 1969 (4.1) | 15 (3.2) |
| Heart failure (%) | 4412 (2.7) | 927 (2.9) | 1276 (3.2) | 571 (2.5) | 374 (1.8) | 1250 (2.6) | 14 (3.0) |
| Ischemic heart disease (%) | 10 509 (6.4) | 2379 (7.6) | 2582 (6.5) | 1561 (7.0) | 1190 (5.8) | 2770 (5.7) | 27 (5.8) |
| Diabetes (%) | 27 269 (16.7) | 4819 (15.3) | 6410 (16.0) | 6117 (27.3) | 2686 (13.1) | 7114 (14.7) | 123 (26.6) |
| COPD (%) | 1831 (1.1) | 465 (1.5) | 381 (1.0) | 256 (1.1) | 239 (1.2) | 485 (1.0) | 5 (1.1) |
| Asthma (%) | 2372 (1.5) | 458 (1.5) | 612 (1.5) | 298 (1.3) | 286 (1.4) | 709 (1.5) | 9 (1.9) |
| Cerebrovascular disease (%) | 6527 (4.0) | 1427 (4.5) | 1885 (4.7) | 745 (3.3) | 689 (3.4) | 1769 (3.7) | 12 (2.6) |
| Medications | |||||||
| Antithrombotic (%) | 12 382 (7.6) | 2676 (8.5) | 3184 (8.0) | 2327 (10.4) | 1175 (5.7) | 2974 (6.2) | 46 (9.9) |
| Steroid (%) | 3635 (2.2) | 616 (2.0) | 1220 (3.0) | 564 (2.5) | 272 (1.3) | 955 (2.0) | 8 (1.7) |
| Hemodialysis (%) | 1089 (0.7) | 224 (0.7) | 335 (0.8) | 149 (0.7) | 82 (0.4) | 292 (0.6) | 7 (1.5) |
| Cancer stage | |||||||
| 0 (%) | 2702 (1.7) | 29 (0.1) | 589 (1.5) | 291 (1.3) | 34 (0.2) | 1759 (3.6) | 0 (0) |
| I (%) | 52 743 (32.3) | 11 146 (35.4) | 5166 (12.9) | 3566 (15.9) | 16 707 (81.7) | 16 006 (33.1) | 152 (32.8) |
| II (%) | 41 982 (25.7) | 7315 (23.2) | 12 861 (32.1) | 6622 (29.5) | 2130 (10.4) | 12 819 (26.5) | 235 (50.8) |
| III (%) | 45 115 (27.6) | 9146 (29.0) | 14 061 (35.1) | 6355 (28.3) | 1282 (6.3) | 14 208 (29.4) | 63 (13.6) |
| IV (%) | 20 652 (12.7) | 3863 (12.3) | 7339 (18.3) | 5587 (24.9) | 285 (1.4) | 3565 (7.4) | 13 (2.8) |
| Surgical information | |||||||
| High‐volume center (%) | 91 653 (56.2) | 24 369 (77.4) | 31 455 (78.6) | 13 372 (59.6) | 17 953 (87.8) | 42 288 (87.4) | 336 (72.6) |
| Anesthesia time (min) (mean (SD)) | 301 (95.8) | 310.8 (97.2) | 272.6 (112.2) | 495.3 (172.9) | 384.7 (103.7) | 332.6 (118.2) | 390.2 (135.3) |
| Treatment | |||||||
| Anti‐adhesive barrier | 61 926 (37.9) | 17 344 (55.1) | 19 867 (49.6) | 8545 (38.1) | 3039 (14.9) | 13 029 (26.9) | 102 (22.0) |
3.2. Propensity Score Matching
After PS matching, we obtained matched pairs for each category:
Open Stomach: 13 938 pairs.
Open Colorectum: 18 603 pairs.
Open Hepatobiliary‐pancreas: 8534 pairs.
Laparoscopic Stomach: 3027 pairs.
Laparoscopic Colorectum: 13 027 pairs.
Laparoscopic Hepatobiliary‐pancreas: 97 pairs.
The baseline demographic, clinical characteristics of each category before matching are described on the left side and those after matching are on the right side of Tables [Link], [Link]. Figure 2 shows the ASD distribution for each variable before and after PS matching for each category. The ASD after matching was less than 0.1 for almost all variables except for some variables in the Laparoscopic Hepatobiliary–pancreas category.
FIGURE 2.
Graph of the distribution of ASD for each variable before and after PS matching in each category: (a) Open Stomach, (b) Open Colorectum, (c) Open Hepatobiliary‐pancreas, (d) Laparoscopic Stomach, (e) Laparoscopic Colorectum, and (f) Laparoscopic Hepatobiliary‐pancreas.
3.3. Survival Analysis
Figure 3 shows the cumulative incidence curve of adhesive bowel obstruction for each category. In the Open Colorectum and Laparoscopic Colorectum categories, the treatment group exhibited fewer outcomes compared to the comparison group, with minimal overlap in the 95% CIs throughout the observation period (log‐rank test; Open Colorectum: p < 0.01, Laparoscopic Colorectum: p = 0.01) [Correction added on 2 February 2026, after first online publication: The p values of log‐rank test of Laparoscopic Colorectum has been corrected.]. In the Open Stomach, Open Hepatobiliary‐pancreas, and Laparoscopic Stomach categories, the cumulative incidence curves of the two groups were close or overlapped for most of the observation period (log‐rank test; Open Stomach: p = 0.1, Open Hepatobiliary‐pancreas: p = 0.5, Laparoscopic Stomach: p = 1.0) [Correction added on 2 February 2026, after first online publication: The p values of log‐rank test; Open Stomach, Open Hepatobiliary pancreas and Laparoscopic stomach have been corrected.]. In the Laparoscopic Hepatobiliary‐pancreas category, the matched cohort size was too small to generate a meaningful cumulative incidence curve.
FIGURE 3.
Cumulative incidence curves for each category: (a) Open Stomach, (b) Open Colorectum, (c) Open Hepatobiliary‐pancreas, (d) Laparoscopic Stomach, (e) Laparoscopic Colorectum, and (f) Laparoscopic Hepatobiliary‐pancreas [Correction added on 2 February 2026, after first online publication: Figure 3 has been replaced.].
Figure S1 shows the log‐minus‐log plots of each category. In the Open Colorectum and Laparoscopic Colorectum categories, the plots for the two groups were approximately parallel without intersecting, suggesting the proportional hazards assumption was not violated. Table 2 presents the number of outcomes in each category, the outcome rate per 100 person‐years, and the adjusted HR obtained from the univariate Cox regression model. In the Open Colorectum and Laparoscopic Colorectum categories, the treatment group had fewer outcomes and a lower outcome rate compared to the comparison group. The adjusted HR was less than 1.0, with the 95% CI excluding 1.0 [Correction added on 2 February 2026, after first online publication: The HR values of Open Colorectum and Laparoscopic Colorectum have been corrected.]:
Open Colorectum: HR = 0.87 (95% CI: 0.80–0.95)
Laparoscopic Colorectum: HR = 0.84 (95% CI: 0.73–0.96)
TABLE 2.
Outcome summary of each category [Correction added on 2 February 2025, after first online publication: Table 2 has been corrected.].
| Comparison | Treatment | ||||||
|---|---|---|---|---|---|---|---|
| Matching Pair | Outcome (%) | Outcome Rate (/100 person‐year) | Outcome (%) | Outcome Rate (/100 person‐year) | HR (95% CI) | ||
| Open | Stomach | 13 938 | 766 (5.5) | 2.33 | 764 (5.5) | 2.10 | 0.92 (0.83–1.01) |
| Colorectum | 18 603 | 1 141 (6.1) | 2.70 | 1 048 (5.6) | 2.29 | 0.87 (0.80–0.95) | |
| Hepatobiliary Pancreas | 8 534 | 187 (2.2) | 0.96 | 181 (2.1) | 0.91 | 0.94 (0.76–1.15) | |
| Laparoscopy | Stomach | 3 027 | 93 (3.1) | 0.97 | 95 (3.1) | 0.95 | 0.99 (0.75–1.32) |
| Colorectum | 13 027 | 442 (3.4) | 1.22 | 381 (2.9) | 1.02 | 0.84 (0.73–0.96) | |
| Hepatobiliary Pancreas | 97 | 0 (0.0) | 0 | 1 (1.0) | < 0.01 | — | |
In the Open Stomach, Open Hepatobiliary‐pancreas, and Laparoscopic Stomach categories, the outcome rates varied between groups, but the 95% CIs for the adjusted HR included 1.0 [Correction added on 2 February 2026, after first online publication: The HR values of Open Stomach, Open Hepatobiliary‐pancreas and Laparoscopic Stomach have been corrected.]:
Open Stomach: HR = 0.92 (95% CI: 0.83–1.01)
Open Hepatobiliary‐pancreas: HR = 0.94 (95% CI: 0.76–1.15)
Laparoscopic Stomach: HR = 0.99 (95% CI: 0.75–1.32)
In the Laparoscopic Hepatobiliary‐pancreas category, the number of matched pairs and outcomes was too small to estimate an HR.
4. Discussion
Using the DPC database, we investigated the effectiveness of anti‐adhesion barriers use in preventing adhesive bowel obstruction following abdominal gastroenterological cancer surgery. We categorized cases into six categories based on surgical approach and target organ, further classifying each category into treatment and comparison groups according to anti‐adhesion barriers usage during surgery. PS matching was applied within each category to ensure covariate balance, and survival analysis was performed with hospitalization due to adhesive bowel obstruction as the primary outcome. Our findings showed that, during the observation period, the treatment group in the Open Colorectum and Laparoscopic Colorectum categories had a significantly lower incidence of adhesive bowel obstruction compared to the comparison group. In contrast, in all other categories, there were no significant differences in outcomes between the two groups. In the Open Colorectum and Laparoscopic Colorectum categories, the log‐minus‐log plots indicated that the proportional hazards assumption was met. The HR was < 1.0, with the 95% CI excluding 1.0, indicating a lower risk of adhesive bowel obstruction in the treatment group.
Our results suggest that anti‐adhesion barriers are effective in preventing adhesive bowel obstruction in patients at high risk of developing adhesive bowel obstruction. Intraperitoneal organs are protected by serous fluid circulating in the abdominal cavity and serous membranes covering organ surfaces [23]. During surgery, the drying of serous fluid and damage to the peritoneal membrane caused by surgical manipulation trigger wound healing processes, leading to adhesion formation on organ surfaces. In colorectal surgery, the intestinal tract is subjected to frequent and direct manipulation, increasing the risk of injury to the intestinal surface [24, 25]. Since the primary site of disease in adhesive bowel obstruction is the intestinal tract, adhesion formation in this region may theoretically increase the risk of disease. In contrast, during stomach and hepatobiliary‐pancreas surgeries, direct manipulation of the intestinal tract is less frequent, except during the reconstruction phase [26, 27, 28, 29, 30]. This difference in surgical manipulation may explain why anti‐adhesion barriers were associated with a reduced risk of adhesive bowel obstruction in the colorectal categories but showed no significant effect in the stomach and hepatobiliary‐pancreas categories. Benign diseases were not included in the study population because the use of anti‐adhesion barriers is not recommended in cases of active inflammation, such as infectious diseases. However, if used appropriately with consideration of the degree of inflammation, the findings of this study may also be applicable to surgical cases involving benign conditions.
This study provides valuable insights into the effectiveness of anti‐adhesion barriers in preventing adhesive bowel obstruction. Previous studies have primarily focused on single organs or procedure [7, 8, 9, 10, 11, 12, 13, 14, 15]. More recently, database studies have been conducted, incorporating organ‐specific analyses [16]. In this study, we applied survival time analysis to evaluate outcomes for each surgical procedure and organ using a large, real‐world database, providing detailed information by visualizing the time trend in the incidence of adhesive bowel obstruction using a cumulative incidence curve. Our findings could be highly suggestive, considering the distinct characteristics of each procedure and organ, including the pathophysiology of adhesive bowel obstruction.
There are several limitations in this study. First, the outcome of this study may not always accurately reflect adhesive bowel obstruction, the primary issue of interest. In the absence of prior studies utilizing the same database, the outcome was independently defined. However, when comparing the incidence of adhesive bowel obstruction in this study population (7483 out of 163 194 cases; 4.6%) with previously reported rates in the literature (approximately 2.4%–10%, varying by organ and procedure), no significant discrepancies were observed. Although the causes of bowel obstruction are varied and there is still a possibility of misclassification in the diagnosis of adhesive bowel obstruction, this could suggest that the definition used in this study is relatively appropriate [1, 31, 32, 33, 34].
Second, some important factors related to adhesive bowel obstruction, such as a history of prior surgeries before the observation period and detailed intraoperative information (e.g., specific procedures and blood loss volume), were not captured in the database. Although propensity score matching was used to adjust for covariates, residual confounding may still exist due to the unavailability of these variables.
Third, follow‐up data based on outpatient visits and hospitalization records may not comprehensively represent actual follow‐up status. Some patients might have sought care at multiple institutions, and surgeries or postoperative follow‐ups might have been conducted at different facilities. As a result, tracking patients who were transferred to other institutions was not possible, a limitation inherent to the nature of the database. However, the follow‐up in this study was reasonably comparable to previously reported data. In the CONCORD‐3 Study, the 5‐year relative survival rates (2010–2014) in Japan were reported as follows: 60.3% for the stomach, 67.8% for the colon, 64.8% for the rectum, 30.1% for the liver, and 8.3% for the pancreas [35]. In this study, the proportion of patients who were followed for at least 5 years postoperatively, regardless of outcome occurrence, was 46.6% for the stomach, 47.2% for the small intestine/colon, 51.0% for the rectum/anus, 41.1% for the liver, and 29.0% for the biliary tract/pancreas. Although the follow‐up rates for each organ were lower than those in the CONCORD‐3 study, this difference may be attributed to the distinction between relative survival rates reported in the CONCORD‐3 study and the observed survival rates in this study. Given these considerations, the follow‐up method in this study appears to be reasonable to some extent for survival analysis.
Fourth, this study was conducted using a database from Japan, and the frequency and background of anti‐adhesion barrier use observed in this study are specific to Japan and may not be directly generalizable to other countries. However, since no racial differences have been reported in adhesion formation or the effects of anti‐adhesion agents, the findings of this study are expected to be applicable to other populations as well. Although the pricing and supply systems of anti‐adhesion barriers are likely to vary across countries, the results of this study may serve as a valuable reference for discussions regarding the appropriate indications and conditions for their use in different healthcare settings.
5. Conclusions
This study suggested that anti‐adhesion barriers could be effective in preventing adhesive bowel obstruction in patients undergoing Open Colorectum and Laparoscopic Colorectum surgery, but not in patients undergoing Open Stomach, Open Hepatobiliary‐pancreas, or Laparoscopic Stomach surgeries. Due to the limited number of cases, we were unable to conduct a sufficient statistical analysis for laparoscopic hepatobiliary‐pancreatic surgeries; therefore, conclusions regarding this group remain inconclusive. As adhesive bowel obstruction remains a critical complication in gastroenterological surgeries, this finding could highlight the potential role of anti‐adhesion barriers in improving surgical outcomes. Given the ongoing interest in this field and the continued implementation of prospective studies, further research is warranted to address the limitations of this study—such as the inability to adjust for key clinical factors—and to confirm the effectiveness and broader applicability of anti‐adhesion barriers in clinical practice.
Author Contributions
Shota Ebinuma: conceptualization, methodology, data curation, investigation, validation, formal analysis, writing – original draft, writing – review and editing, visualization. Susumu Kunisawa: methodology, writing – review and editing, supervision, software. Daisuke Takada: methodology, writing – review and editing. Kiyohide Fushimi: writing – review and editing, resources. Akinobu Taketomi: writing – review and editing. Yuichi Imanaka: project administration, writing – review and editing, funding acquisition.
Ethics Statement
This study was approved by the Ethics Committee of the Graduate School of Medicine, Kyoto University (Approval number: R0135).
Consent
Data for this study was anonymized, and individual informed consent was waived.
Conflicts of Interest
The authors declare no conflicts of interest.
Supporting information
Figure S1: Log‐minus‐log plots for each category: (a) Open Stomach, (b) Open Colorectum, (c) Open Hepatobiliary‐pancreas, (d) Laparoscopic Stomach, (e) Laparoscopic Colorectum, and (f) Laparoscopic Hepatobiliary‐pancreas [Correction added on 2 February 2026, after first online publication: Figure S1 has been replaced.].
Table S1: List of operation K codes using in this study.
Table S2: List of ICD‐10 codes using in this study.
Table S3: Baseline characteristics between treatment and comparison groups for Open Stomach category before and after matching.
Table S4: Baseline characteristics between treatment and comparison groups for Open Colorectum category before and after matching.
Table S5: Baseline characteristics between treatment and comparison groups for Open Hepatobiliary‐pancreas category before and after matching.
Table S6: Baseline characteristics between treatment and comparison groups for Laparoscopic Stomach category before and after matching.
Table S7: Baseline characteristics between treatment and comparison groups for Laparoscopic Colorectum category before and after matching.
Table S8: Baseline characteristics between treatment and comparison groups for Laparoscopic Hepatobiliary‐pancreas category before and after matching.
Funding: This study received support from the Health and Labour Sciences Research Grant (Grant Number: JPMH24AA2006 and JPMH25IA1002) from the Ministry of Health, Labour and Welfare, and JSPS KAKENHI (Grant Number JP23H00448) from the Japan Society for the Promotion of Science (awarded to Yuichi Imanaka). The funders had no role in the study design, data collection and analysis, decision to publish, or manuscript preparation.
Data Availability Statement
The data that support the findings of this study are available from the corresponding author upon reasonable request. The database generated and analyzed during the study can be obtained from the corresponding author upon reasonable request.
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Associated Data
This section collects any data citations, data availability statements, or supplementary materials included in this article.
Supplementary Materials
Figure S1: Log‐minus‐log plots for each category: (a) Open Stomach, (b) Open Colorectum, (c) Open Hepatobiliary‐pancreas, (d) Laparoscopic Stomach, (e) Laparoscopic Colorectum, and (f) Laparoscopic Hepatobiliary‐pancreas [Correction added on 2 February 2026, after first online publication: Figure S1 has been replaced.].
Table S1: List of operation K codes using in this study.
Table S2: List of ICD‐10 codes using in this study.
Table S3: Baseline characteristics between treatment and comparison groups for Open Stomach category before and after matching.
Table S4: Baseline characteristics between treatment and comparison groups for Open Colorectum category before and after matching.
Table S5: Baseline characteristics between treatment and comparison groups for Open Hepatobiliary‐pancreas category before and after matching.
Table S6: Baseline characteristics between treatment and comparison groups for Laparoscopic Stomach category before and after matching.
Table S7: Baseline characteristics between treatment and comparison groups for Laparoscopic Colorectum category before and after matching.
Table S8: Baseline characteristics between treatment and comparison groups for Laparoscopic Hepatobiliary‐pancreas category before and after matching.
Data Availability Statement
The data that support the findings of this study are available from the corresponding author upon reasonable request. The database generated and analyzed during the study can be obtained from the corresponding author upon reasonable request.