Abstract
Introduction
Enhanced recovery after surgery (ERAS) is a widely accepted program aimed at improving short-term outcomes in patients undergoing colorectal surgery. To achieve good postoperative outcomes, adherence of at least 75% to ERAS principles is required, which is particularly challenging during the postoperative period.
Methods
Patients undergoing colorectal resection between May 2016 and October 2022 were prospectively enrolled in the ERAS protocol and stratified according to the retrospectively assessed CCI. Patients with ≥ 5% missing data were excluded. The primary outcome was to evaluate the predictive value of the Charlson Comorbidity Index (CCI) for achieving adequate postoperative ERAS adherence (≥ 75%).
Results
A total of 572 patients were included (CCI 0: 223 [39.0%], CCI 1: 41 [7.2%], CCI 2: 150 [26.2%], CCI 3: 71 [12.4%], CCI ≥ 4: 87 [15.2%]). Patients with a CCI score of 0 had a median postoperative ERAS adherence of 84.6% (range: 15.4–100) compared with 69.2% (range: 16.7–100) in patients with a CCI score of ≥ 4 (p < 0.001). Increasing CCI was significantly associated with a higher complication index (p < 0.001) and a longer length of hospitalization stay (p < 0.001). In the multivariate analysis, CCI ≥ 2 was an independent predictor of failure to achieve adequate postoperative ERAS adherence (≥ 75%).
Conclusion
Higher CCI was associated with lower postoperative ERAS adherence. Based on these findings, an exploratory risk-stratification algorithm is proposed to facilitate the preoperative identification of patients at increased risk for inadequate postoperative ERAS adherence.
Supplementary Information
The online version contains supplementary material available at https://doi.org/10.1186/s12893-026-04051-3.
Keywords: Enhanced recovery after surgery (ERAS), Colorectal surgery, Charlson Comorbidity Index, Postoperative ERAS adherence, Risk stratification
Introduction
The enhanced recovery after surgery (ERAS) program was developed to reduce patients’ recovery time after surgery by minimizing the perioperative stress response [1]. Nowadays, ERAS is a widely accepted concept in the perioperative management of patients across various surgical fields and has been shown to improve short-term outcomes [2]. Implementation of ERAS is associated with lower rates of postoperative complications and a shorter length of hospital stay (LOS) [2–6].
The ERAS program divides the perioperative period into four phases, with specific principles recommended for each phase [7]. Adherence to these principles is measured using a point-based system, with a maximum adherence score of 100% per phase. To achieve the full clinical benefit of ERAS, an adherence score of at least 75% is required [8]. Previous studies have demonstrated that adherence to ERAS principles is lowest during the postoperative ERAS phase, mainly due to the high activity level required from both patients and healthcare professionals [9, 10]. However, the factors influencing adherence during the postoperative ERAS phase remain insufficiently understood, potentially leading to a suboptimal postoperative phase. In a previous study, we investigated the impact of patients´ age on the postoperative ERAS phase. Although older age was associated with a lower postoperative ERAS adherence, age was not identified as an independent predictor [11]. This highlights the need to consider additional factors, such as comorbidities, which are well known to influence the postoperative clinical course [12].
The aim of this study was to evaluate the predictive value of CCI with respect to postoperative ERAS adherence and its subsequent impact on the short-term clinical outcome [13, 14]. Based on the study findings, an exploratory risk-stratification algorithm is proposed to facilitate the identification of patients at increased risk of inadequate postoperative ERAS adherence.
Methods
Study design
This study is a retrospective analysis of prospectively collected ERAS data of patients undergoing colorectal resections in the Department of Surgery at Cantonal Hospital Baselland, Switzerland. Since the implementation of the ERAS program in 2016, the Department of Surgery at Cantonal Hospital Baselland has been a certified ERAS center and, since 2017, a certified colorectal cancer center. In accordance with the recommendations of the ERAS® Society, all ERAS-related data were prospectively recorded in an interactive ERAS audit system by a specially trained ERAS nurse. Demographic and clinical data were retrieved from the ERAS system and the patients’ medical records.
All included patients provided written general consent. The study was approved by the Ethics Committee of Northwestern and Central Switzerland (KEK-Nr. 2023 − 01684).
Study population
All adult patients (> 18 years old) undergoing colorectal resection between May 1, 2016 and October 31, 2022 at the Department of Surgery of the Cantonal Hospital Baselland, Switzerland, were eligible for inclusion. Colorectal resections were performed with primary anastomosis and/or with definitive or temporary stoma formation. Inclusion required a postoperative ERAS dataset with less than 5% missing data. Patients with more than 5% missing ERAS data were excluded from the analysis, as a higher proportion of missing values was considered likely to compromise the reliability of the ERAS adherence assessment. Missing data resulted from incomplete ERAS documentation during a limited study period rather than from patient-related factors. Missing ERAS items were recorded as a separate category and were not imputed. Furthermore, no patients with chronic inflammatory bowel disease were included in the cohort.
ERAS program and perioperative management
All patients were managed perioperatively according to an ERAS protocol adapted from the ERAS® Society guidelines [7]. In this study, the postoperative ERAS phase comprised a total of 13 recommended principles (Supplementary Data Fig. 1). Full adherence to all recommended principles corresponded to an adherence score of 100%. An adherence score of ≥ 75%, which is recommended to achieve the full clinical benefit of ERAS, was therefore defined as sufficient adherence.
During hospitalization, all patients received low-molecular-weight heparin in a prophylactic dose and those who required full anticoagulation were fully heparinized based on the indication for anticoagulation and the bleeding risk. To enhance intestinal motility, all patients initially received magnesium orally. Subsequently, medical therapy was extended to metoclopramide, gastrographin, or neostigmine if needed. All medications were prescribed following a thorough assessment of any contraindications. The standard basic analgesic regimen was acetaminophen combined with metamizole sodium monohydrate. Additionally, patients received either patient-controlled analgesia (PCA) pumps or epidural anesthesia (PDA). When pain control after the removal of PCA and PDA was inadequate, patients were administered oxycodone in combination with naloxone during hospitalization. Upon discharge, patients were typically prescribed basic analgesic therapy. No non-steroidal anti-inflammatory drugs (NSAIDs) were administered.
Charlson Comorbidity Index (CCI)
The original CCI as described by Charlson et al., excluding age, was used in this study [15]. This version includes 16 chronic diseases coded according to the International Classification of Diseases, 10th Revision (ICD-10) (Supplementary Data Fig. 2).
CCI was assessed retrospectively for all included patients. Patients with a CCI score of ≥ 4 were grouped together for analysis.
Outcomes and variables
The primary endpoint was to evaluate the predictive value of the CCI for achieving adequate postoperative ERAS adherence (≥ 75%). Secondary endpoints included the association of CCI with postoperative complications and LOS.
LOS was defined as the number of nights spent in hospital after surgery. Patients undergoing elective surgery were admitted one day before surgery, whereas emergency patients were admitted following presentation to the emergency department. Emergency surgery was defined according to ERAS® Society recommendations as surgery performed within 2 h, within 2 to 48 h, or more than 48 h after emergency department assessment. These categories were summarized as emergency surgery. Emergency patients provided informed consent on postoperative day 1, while all other patients provided consent during the preoperative consultation.
Conversions from minimally invasive to open procedures were classified as open surgery. Postoperative complications, defined as any medical or surgical deviation from the normal postoperative course, were classified according to the Clavien–Dindo classification and summarized as the complication index (IC) [16, 17]. Postoperative ileus was defined as impaired gastrointestinal motility requiring a nasogastric tube placement. Anastomotic leakage was either confirmed using reoperation or endoscopic intervention or diagnosed based on documented extraluminal air or contrast leakage adjacent to the anastomosis. All complications occurring within 30 days after operation were included. The American Society of Anesthesiologists (ASA) scores were grouped as I/II and III/IV.
Furthermore, all patients were included in a multivariable logistic regression analysis to identify factors associated with achieving adequate postoperative ERAS adherence (≥ 75%). Adequate postoperative ERAS adherence was defined as an adherence score ≥ 75%. To further evaluate the influence of malignancy on the Charlson Comorbidity Index (CCI), subgroup analyses were performed separately in patients with benign and malignant disease. Multivariable logistic regression analyses were repeated within each subgroup using the same covariates as in the primary analysis.
In addition, adherence to the individual postoperative ERAS items was analyzed. Poor adherence was defined as fulfillment of a given item in fewer than 75% of patients.
Statistical analysis
Statistical analyses were performed using the R (version 4.1.2). Descriptive and univariable analyses were conducted using Student’s t test and the Mann–Whitney U test for normally and non-normally distributed continuous variables, respectively, and the results are presented as medians. Categorical variables were analyzed using the chi-square test. Multivariable binary logistic regression was performed to identify factors associated with achieving adequate postoperative ERAS adherence (≥ 75%). The results are reported as odds ratios (ORs) with corresponding 95% confidence intervals (CI). To avoid temporal bias, variables available before or at the time of surgery were included in the multivariable model; postoperative variables were excluded. For multivariable analysis, the CCI was dichotomized as < 2 and ≥ 2, ASA was grouped as I/II versus III/IV, and colorectal procedures were categorized as right-sided colorectal procedures (ileocecal resection and right hemicolectomy), left-sided colorectal procedures (left hemicolectomy, sigmoid resection, anterior rectal resection, and low anterior rectal resection), or total colectomy. Independent predictors identified in the multivariable analysis were additionally assessed for multicollinearity to exclude potential correlations between variables. Statistical significance was defined as p ≤ 0.05.
Results
Patient characteristics
During the 6-year study period, a total of 608 patients underwent colorectal surgery with perioperative care according to the ERAS protocol. During the exclusion process, 36 (5.9%) patients were excluded based on the predefined criteria (Fig. 1). The remaining 572 (94.1%) were included in the final analysis and stratified into five groups according to their CCI score (CCI 0 n = 223 [39.0%], CCI 1: n = 41 [7.2%], CCI 2: n = 150 [26.2%], CCI 3: n = 71 [12.4%], CCI ≥ 4: n = 87 [15.2%]; Fig. 1).
Fig. 1.
Flow chart of the study cohort. CCI, Charlson comorbidity index; ERAS, enhanced recovery after surgery
Patient characteristics are summarized in Table 1. The median age in the CCI ≥ 4 patient group was significantly higher than in the CCI 0 group (CCI 0: 61 [range 18–89] years vs. CCI ≥ 4: 74 [range 49–88] years). There were more male patients in the CCI ≥ 4 group with significantly higher ASA scores III/IV (CCI 0: 49 [22.0%] patients vs. CCI ≥ 4: 80 [92.0%] patients; p < 0.001). Regarding the CCI score, patients received two points for localized solid tumors. Therefore, the patients in CCI groups 0 and 1 had only non-malignant underlying diseases. Consequently, the presence of malignancies differed significantly among the CCI groups (p < 0.001).
Table 1.
Patient characteristics of the study cohort in accordance with the CCI
| All (n = 572) |
CCI 0 (n = 223) |
CCI 1 (n = 41) |
CCI 2 (n = 150) |
CCI 3 (n = 71) |
CCI ≥ 4 (n = 87) |
p-value | |
|---|---|---|---|---|---|---|---|
| Age | 66.2 (18–93) | 61 (18–89) | 71 (37–87) | 68 (24–92) | 74 (46–93) | 74 (49–88) | |
| BMI | 26.1 (12.1–45.1) | 26.4 (16.6–45.1) | 26.7 (18.6–40.8) | 25.8 (17.8–39.4) | 26.7 (12.1–38.3) | 25 (17.3–40.3) | 0.2 |
| Gender (male) | 289 (52.1%) | 99 (44.4%) | 16 (39.0%) | 77 (51.3%) | 50 (70.4%) | 56 (64.4%) | < 0.001 |
| ASA | < 0.001 | ||||||
| 1 + 2 | 227 (39.37%) | 174 (78.0%) | 20 (48.8%) | 21 (14.0%) | 5 (7.0%) | 7 (8.0%) | |
| 3 + 4 | 345 (60.3%) | 49 (22.0%) | 21 (51.2%) | 129 (86.0%) | 66 (93.0%) | 80 (92.0%) | |
| Tumor type | < 0.001 | ||||||
| Benign | 283 (49.5%) | 223 (78.8%) | 41 (14.5%) | 11 (3.9%) | 8 (2.8%) | 0 | |
| Malignant | 289 (50.5%) | 0 | 0 | 139 (48.1%) | 63 (21.8%) | 87 (30.1%) |
Age, median, BMI Body mass index (kg/m2), median, ASA American society of Anesthesiologists score
Surgical data and clinical outcome
In the CCI 0 patient group, significantly more patients underwent emergency intervention (p = 0.04) and received minimally invasive treatments (p < 0.001). Among patients with a CCI of 0, sigmoid resections were most commonly performed (n = 192 [86.1%]), whereas anterior resections were the most frequent surgical procedures in patients with a CCI ≥ 4 (n = 33 [37.9%]) (Table 2). The median blood loss and duration of surgery differed significantly among the groups (both p < 0.001). The median LOS increased with higher CCI scores (6 days [range 3–21] in the CCI 0 group vs. 11 days [range 5–29] in the CCI ≥ 4 group; p < 0.001; Table 2). Significantly more patients with a CCI ≥ 4 were discharged to other healthcare facilities (p < 0.001).
Table 2.
Surgical outcome in study cohort according to CCI. Open surgical approach including conversion from minimally invasive to open
| All (n = 572) |
CCI 0 (n = 223) |
CCI 1 (n = 41) |
CCI 2 (n = 150) |
CCI 3 (n = 71) |
CCI ≥ 4 (n = 87) |
p-value | |
|---|---|---|---|---|---|---|---|
| Surgery scheduling type | |||||||
| Elective | 509 (89.0%) | 187 (83.9%) | 37 (90.2%) | 140 (93.3%) | 65 (91.5%) | 80 (92.0%) | |
| Emergency | 63 (11.0%) | 36 (16.1%) | 4 (9.8%) | 10 (6.7%) | 6 (8.5%) | 7 (8.0%) | |
| Surgical approach | < 0.001 | ||||||
| Open | 131 (22.9%) | 23 (10.3%) | 4 (9.8%) | 40 (26.7%) | 27 (38.0%) | 37 (42.5%) | |
| Laparoscopic/robotic | 441 (77.1%) | 200 (89.7%) | 37 (90.2%) | 110 (73.3%) | 44 (62.0%) | 50 (57.5%) | |
| Surgical procedure | < 0.001 | ||||||
| Right hemicolectomy/ileocecal | 132 (23.1%) | 16 (7.2%) | 5 (12.2%) | 54 (36.0%) | 29 (40.8%) | 28 (32.2%) | |
| Left hemicolectomy | 35 (6.1%) | 6 (2.7%) | 1 (2.4%) | 9 (6.0%) | 8 (11.3%) | 11 (12.6%) | |
| Sigmoid resection | 289 (50.5%) | 192 (86.1%) | 34 (82.9%) | 36 (24.0%) | 15 (21.1%) | 12 (13.8%) | |
| Anterior resection | 101 (17.7%) | 5 (2.2%) | 1 (2.4%) | 44 (29.3%) | 18 (25.4%) | 33 (37.9%) | |
| Abdominoperineal resection | 5 (0.9%) | 1 (0.4%) | 0 | 3 (2.0%) | 0 | 1 (1.1%) | |
| Total/subtotal colectomy | 10 (1.7%) | 3 (1.3%) | 0 | 4 (2.7%) | 1 (1.4%) | 2 (2.3%) | |
| Blood loss (ml, median) | 50 (0-3000) | 20 (0-700) | 50 (5-250) | 37.5 (0-1800) | 50 (0-800) | 50 (0-3000) | < 0.001 |
| Duration of the surgical procedure | 200 (80–500) | 180 (80–470) | 185 (90–360) | 211 (100–480) | 225 (100–486) | 240 (90–500) | < 0.001 |
CCI Charlson comorbidity index
The overall complication rates increased with higher CCI scores (p < 0.001). Furthermore, patients with a CCI ≥ 4 experienced significantly more >3a complications according to the Clavien–Dindo classification and, consequently, had a higher index of complication (p < 0.001 each, Table 3).
Table 3.
Clinical outcome in study cohort according to CCI
| All (n = 572) |
CCI 0 (n = 223) | CCI 1 (n = 41) |
CCI 2 (n = 150) | CCI 3 (n = 71) |
CCI ≥ 4 (n = 87) | p-value | |
|---|---|---|---|---|---|---|---|
| LOS | 8.7 (3–42) | 6 (3–21) | 7 (5–28) | 7.5 (3–27) | 7 (5–42) | 11 (5–29) | < 0.001 |
| Discharge | < 0.001 | ||||||
| Home | 461 (80.0%) | 207 (92.8%) | 40 (97.6%) | 116 (77.3%) | 46 (64.8%) | 52 (59.8%) | |
| Other institutions | 111 (19.4%) | 16 (7.2%) | 1 (2.4%) | 34 (22.7%) | 25 (35.2%) | 35 (40.2%) | |
| Overall complications* | < 0.001 | ||||||
| No | 370 (64.7%) | 165 (74.0%) | 27 (65.9%) | 97 (64.7%) | 41 (57.7%) | 40 (46.0%) | |
| Yes | 202 (35.3%) | 58 (26.0%) | 14 (34.1%) | 53 (35.3%) | 30 (42.3%) | 47 (54.0%) | |
| Severity of complications° | < 0.001 | ||||||
| 1-3a | 140 (24.5%) | 39 (17.4%) | 6 (14.6%) | 44 (29.3%) | 23 (32.4%) | 28 (32.2%) | |
| 3b-4b | 64 (11.2%) | 19 (8.5%) | 8 (19.5%) | 9 (6.0%) | 7 (9.9%) | 19 (21.8%) | |
| Index of complications | 10.6 (0-76.7) | 7.2 (0-58.4) | 11.2 (0-59.9) | 10.3 (0-74.2) | 11.8 (0-68.6) | 18.4 (0-76.7) | < 0.001 |
| Postoperative ileus | < 0.001 | ||||||
| No | 495 (86.5%) | 210 (94.2%) | 37 (90.2%) | 126 (84.0%) | 59 (83.1%) | 63 (73.4%) | |
| Yes | 77 (13.5%) | 13 (5.8%) | 4 (9.8%) | 24 (16.0%) | 12 (16.9%) | 24 (27.6%) | |
| Anastomotic leakage | 0.06 | ||||||
| No | 544 (96.5%) | 219 (89.6%) | 40 (97.6%) | 142 (96.6%) | 65 (92.9%) | 78 (92.9%) | |
| Yes | 20 (3.5%) | 3 (1.4%) | 1 (2.4%) | 5 (3.4%) | 5 (7.1%) | 6 (7.1%) |
LOS Length of hospitalization, median (in days), CCI Charlson comorbidity index
° According to Clavien–Dindo classification
* Within 30 days after operation
Adherence of the postoperative ERAS protocol
In the univariate analysis of the study cohort, significantly fewer patients with a CCI ≥ 4 achieved the required postoperative ERAS adherence score of ≥ 75% necessary to obtain a clinical benefit (CCI 0: 162 patients [72.6%] vs. 37 patients [42.5%]; p < 0.001; Table 4). The median postoperative ERAS adherence score, expressed as a percentage, decreased significantly with increasing CCI scores (84.6% [range 23.1–100] in patients with CCI 0 vs. 69.2% [range 16.7–100] in patients with CCI ≥ 4; p < 0.001; Table 3). When comparing group medians, a marked decrease in adherence was observed between patients with CCI scores of 1 and 2, respectively (Fig. 2). A detailed analysis identified seven items with particularly low adherence: mobilization on postoperative days 1–3, oral energy intake on day of surgery and postoperative day 1, duration of intravenous fluid infusion, and balanced fluid on the day of surgery (Supplementary Data Fig. 4).
Table 4.
Postoperative ERAS adherence score in study cohort according to CCI
| All (n = 572) |
CCI 0 (n = 223) |
CCI 1 (n = 41) |
CCI 2 (n = 150) |
CCI 3 (n = 71) |
CCI ≥ 4 (n = 87) |
p-value | |
|---|---|---|---|---|---|---|---|
| Postop. ERAS adh.* | 76.9 (15.4–100) | 84.6 (23.1–100) | 84.6 (25.0-100) | 75.0 (15.4–100) | 75.0 (23.1–100) | 69.2 (16.7–100) | < 0.001 |
| Postop. ERAS adh.° | |||||||
| ≥ 75% | 342 (59.8%) | 162 (72.6%) | 28 (68.3%) | 78 (52.0%) | 37 (52.1%) | 37 (42.5%) | < 0.001 |
| < 75% | 230 (40.2%) | 61 (27.4%) | 13 (31.7%) | 72 (48.0%) | 34 (47.9%) | 50 (57.5%) |
Postoperat. ERAS adh. Postoperative ERAS adherence, CCI Charlson comorbidity index, ERAS Enhanced recovery after surgery
* In %, median (range)
° Number of patients
Fig. 2.
Univariate analysis of the postoperative ERAS adherence (in %) according to the Charlson comorbidity index. In the boxplot, the line represents the median. ERAS, enhanced recovery after surgery
Anastomotic leakage was assessed only in patients who underwent intestinal anastomosis (n = 564). Patients without an anastomosis were excluded from this analysis.
Multivariable and subgroup analyses of postoperative ERAS adherence
All patients were included in the multivariable logistic regression analysis to identify factors associated with achieving adequate postoperative ERAS adherence (≥ 75%). In the overall cohort, a CCI score ≥ 2, an open surgical approach, and left-sided colorectal procedures were independently associated with a lower likelihood of achieving adequate postoperative ERAS adherence (Fig. 3).
Fig. 3.
Multivariable logistic regression analysis identifying independent factors associated with achieving adequate postoperative ERAS adherence ≥ 75%. A CCI ≥ 2, an open surgical approach, and left-sided colorectal procedures were independently associated with a lower likelihood of achieving adequate postoperative ERAS adherence. BMI, body mass index (kg/m²); CCI, Charlson Comorbidity Index; CI, confidence interval; ERAS, enhanced recovery after surgery
To further evaluate the potential influence of malignancy on the relationship between CCI and postoperative ERAS adherence, separate subgroup analyses were performed in patients with benign and malignant disease.
Among patients with benign disease (n = 283), the maximum CCI score was 3 (CCI 0: 223 [78.8%], CCI 1: 41 [14.4%], CCI 2: 11 [3.9%], CCI 3: 8 [2.8%]). The proportion of patients achieving postoperative ERAS adherence ≥ 75% decreased significantly with increasing CCI score (p = 0.009). Similarly, median postoperative ERAS adherence declined significantly with increasing CCI (p = 0.02). Based on the univariable analysis, the most pronounced decrease in adherence was observed between CCI 1 and CCI 2. In multivariable analysis, CCI ≥ 2 and an open surgical approach remained independently associated with failure to achieve adequate postoperative ERAS adherence (Supplementary Figure 3A).
In the malignant disease cohort (n = 289), 139 (48.1%) patients had a CCI score of 2, 63 (21.8%) a score of 3, and 87 (30.1%) a score of ≥ 4. No significant difference was observed in the proportion of patients achieving postoperative ERAS adherence ≥ 75%. However, median postoperative ERAS adherence decreased significantly with increasing CCI score (p=0.04). Based on the univariable analysis, the most pronounced decrease in adherence was observed between CCI 3 and CCI ≥4. Nevertheless, CCI ≥4 was not independently associated with postoperative ERAS adherence in multivariable analysis (Supplementary Figure 3B).
Exploratory risk-stratification algorithm for preoperative assessment of postoperative ERAS adherence
Based on these findings, an exploratory two-step risk-stratification algorithm was developed for preoperative assessment of the risk of inadequate postoperative ERAS adherence (< 75%) (Fig. 4). In the first step, risk assessment is based on the presence of malignancy; in the second step, patients are stratified according to their CCI score. The algorithm is intended as an exploratory tool to facilitate preoperative identification of patients who may be at increased risk for low postoperative ERAS adherence.
Fig. 4.
Proposed exploratory two-step risk-stratification algorithm for identifying patients at increased risk for inadequate postoperative ERAS adherence (< 75%)
For an internal consistency assessment, the study cohort was re-evaluated using this algorithm. A total of 106 patients (18.5%) were classified as being at elevated risk for a postoperative ERAS adherence < 75%. Their characteristics and surgical outcomes are summarized in Supplementary Tables 1 and 2. Significantly fewer patients in the elevated-risk group achieved ERAS adherence ≥ 75% compared with the standard group (42.5% versus 63.9%; p < 0.001). In addition, the median postoperative ERAS adherence was significantly lower in the high-risk group, the hospital stay was longer, and the comprehensive complication index was higher (p < 0.001 each; Table 5).
Table 5.
Short-term outcomes stratified according to the proposed exploratory risk-stratification algorithm
| Patients with normal risk (n = 466) |
Patients with elevated risk (n = 106) |
p-value | |
|---|---|---|---|
| Postoperative ERAS adh.* | 83.3 (15.4–100) | 69.2 (16.7–100) | < 0.001 |
| Postoperative ERAS adh.° | < 0.001 | ||
| ≥ 75% | 298 (63.9%) | 45 (42.5%) | |
| < 75% | 168 (36.1%) | 61 (57.5%) | |
| LOS | 7 (3–42) | 9.5 (4–29) | < 0.001 |
| Discharge | < 0.001 | ||
| Home | 395 (84.8%) | 66 (62.3%) | |
| Other institutions | 71 (15.2%) | 40 (37.7%) | |
| Overall complication* | < 0.001 | ||
| No | 319 (68.5%) | 51 (48.1%) | |
| Yes | 147 (31.5%) | 55 (51.9%) | |
| Severity of complication°° | 0.3 | ||
| 1-3a | 104 (70.7%) | 35 (63.6%) | |
| 3b-4b | 43 (29.3%) | 20 (36.4%) | |
| Index of complications | 9.1 (0-74.2) | 16.9 (0-76.7) | < 0.001 |
| Postoperative ileus | < 0.001 | ||
| No | 415 (89.1%) | 80 (75.5%) | |
| Yes | 51 (10.9%) | 26 (24.5%) | |
| Anastomotic leakage | 0.2 | ||
| No | 447 (97.0%) | 97 (94.2%) | |
| Yes | 14 (3.0%) | 6 (5.8%) |
Postoperat. ERAS adh. Postoperative ERAS adherence, * in %, median (range); ° number of patients; LOS Length of hospitalization, median (in days); °° according to Clavien–Dindo classification; * within 30 days after operation.
Discussion
The present study revealed an association between higher CCI and lower postoperative adherence to the ERAS protocol. Furthermore, patients with a CCI ≥ 2 experienced significantly more postoperative complications and a longer LOS. Based on these findings, an exploratory risk-stratification algorithm is proposed to facilitate preoperative identification of patients at increased risk for inadequate postoperative ERAS adherence and to allow adjustment of postoperative ERAS support.
CCI is a widely accepted and well-validated comorbidity score [13]. This morbidity score reflects a patient’s general medical condition and has been shown to possess superior predictive capacity compared with other preoperative risk assessment tools [18]. Moreover, CCI is simple to apply and is increasingly used as a surrogate marker of frailty—a condition of growing importance in light of demographic changes [19].
In this study, the original CCI was used to assess patient comorbidities. According to the literature, several modified CCI versions exist that differ according to the diseases that are included. A crucial aspect is transparency regarding which CCI version is applied [20]. The present results demonstrated that patients with a higher CCI were older. Although the CCI used in this study did not include age, age itself has previously been shown not to be independently associated with postoperative ERAS adherence [11]. Therefore, the original CCI was considered more appropriate than the age-adjusted version to specifically evaluate the influence of comorbidity burden independent of chronological age.
Although a postoperative ERAS adherence threshold of 75% was used in the present study, no universally accepted cutoff has been established. The selected threshold was based on previous reports suggesting that adherence rates above 70–75% are generally associated with the benefits of ERAS programs [4, 11]. Furthermore, this threshold has been widely adopted in the ERAS literature. Accordingly, a postoperative ERAS adherence threshold of ≥ 75% was used in the present study. Nevertheless, different thresholds may result in different patient classifications, and future studies should further investigate the optimal adherence cutoff associated with improved postoperative outcomes.
The focus of this study was on the postoperative ERAS phase, as adherence during this ERAS phase is typically the lowest due to less standardized protocols and therefore the greatest potential for improvement [10]. During this phase, both patients and healthcare professionals play particularly active roles, which may contribute to deviations from the ERAS protocol. These findings are consistent with the ERAS elements showing the poorest adherence, namely early mobilization on postoperative days 1–3 and sufficient oral energy intake. Additionally, restrictive fluid management may still be insufficiently implemented in routine clinical practice. The reasons for these discrepancies can only be speculated upon. Even among patients with a CCI of 0, fewer than 75% met the oral energy intake criteria on the day of surgery, possibly due to the effects of anesthesia. Among patients with a CCI of ≥ 4, fewer than 75% adhered to the ERAS principles and there was generally poor adherence. In this group, two additional principles showed low adherence: timely removal of urinary drainage and weight changes on postoperative day 1. This observation may reflect a reluctance to strictly adhere to ERAS recommendations in patients with a higher comorbidity burden, who may be perceived as more frail, despite current evidence indicating that age is not a risk factor for non-adherence to the ERAS program. An additional consideration is the temporal relationship between postoperative ERAS adherence and postoperative complications. Patients who develop complications may be less likely to achieve ERAS items such as early mobilization, adequate oral intake, restrictive fluid management, or timely catheter removal. However, achievement of these postoperative ERAS items also depends on the coordinated efforts of the multidisciplinary healthcare team, including timely patient mobilization, optimization of fluid therapy, and removal of urinary catheters according to the ERAS protocol. Therefore, lower postoperative ERAS adherence may reflect both reduced patient capacity and challenges in implementing postoperative ERAS measures in patients with a more complex postoperative course, rather than patient-related factors alone. These challenges may also be influenced by clinical decision-making and the practical implementation of ERAS measures by the multidisciplinary healthcare team. Consequently, causality cannot be inferred from the present observational analysis, and the observed associations should be interpreted with caution. Nevertheless, the multivariable analysis demonstrated that CCI remained an independent factor associated with postoperative ERAS adherence.
In the overall cohort, CCI ≥ 2 was identified as an independent risk factor for failure to achieve adequate postoperative ERAS adherence (≥ 75%) in both univariate and multivariate analyses. However, patients with malignant disease automatically receive two points within the CCI due to the presence of a localized solid tumor and are therefore classified into a higher CCI category. To address the potential confounding effect of malignancy, separate subgroup analyses were performed in patients with benign and malignant disease. In the benign disease cohort, where malignancy does not contribute to the CCI score, higher CCI remained independently associated with a lower likelihood of achieving adequate postoperative ERAS adherence. This finding suggests that the observed association is not solely explained by the tumor component of the CCI and supports an independent contribution of comorbidity burden to failure to achieve adequate postoperative ERAS adherence. In contrast, no independent association between CCI and postoperative ERAS adherence could be demonstrated in the malignant disease cohort after multivariable adjustment. However, these findings should be interpreted with caution, as the number of patients decreased substantially with increasing CCI categories, resulting in limited statistical power and wide confidence intervals in the higher CCI groups.
The first step is to determine whether the disease is benign or malignant, as failing to do so would place all patients with malignant disease into a higher CCI category. Based on these findings, an exploratory risk-stratification algorithm was developed. The algorithm is intended as a pragmatic tool to facilitate preoperative identification of patients who may be at increased risk for inadequate postoperative ERAS adherence. As an internal evaluation, the algorithm was applied to the study cohort, revealing that fewer than 20% of patients were at elevated risk for postoperative ERAS adherence below 75%. This proportion represents a manageable group that could benefit from intensified perioperative care in routine clinical practice. Patients at an increased risk of non-adherence to the postoperative ERAS items may benefit from intensified supervision, including more frequent involvement of specialized ERAS nursing services in collaboration with medical staff to ensure implementation of the required ERAS items. These findings represent an internal assessment of the proposed algorithm and should be interpreted as hypothesis-generating. External validation in an independent cohort is required before routine clinical implementation can be recommended.
Several limitations of this study should be acknowledged. The cohort included a broad spectrum of colorectal diseases and surgical procedures. Consequently, differences in the underlying disease and treatment pathways may have influenced patients’ general condition, postoperative recovery, and adherence to the ERAS program. However, nutritional status, an important determinant of postoperative recovery, is incorporated into the preadmission ERAS phase, and no relevant differences were observed in the remaining ERAS phases within the study cohort. Treatment-related factors such as neoadjuvant chemoradiotherapy were not specifically evaluated and may have influenced postoperative recovery and ERAS adherence.
Furthermore, data on patients’ personal medications, which may affect the postoperative course, were not available. The cohort also included patients undergoing colorectal emergency surgery, which may represent a potential confounder. To account for this, emergency surgery was included as a covariate in the multivariable analysis. Further, current evidence supports the feasibility of the ERAS program in emergency patients [21–23]. In addition, patients with inflammatory bowel disease were not included in the present study, as this patient population differs with regard to the underlying disease process and perioperative therapeutic strategies. Consequently, the applicability of the proposed exploratory risk-stratification algorithm to patients with inflammatory bowel disease requires further investigation. Nevertheless, because of this heterogeneity, the cohort reflects a typical colorectal patient population encountered in routine clinical practice. Although internal consistency was demonstrated within the present cohort, external validation is required before broader implementation can be recommended.
Conclusions
In conclusion, postoperative ERAS adherence was significantly lower in patients with higher CCI scores and was associated with increased complication rates and prolonged hospital stays. Based on these findings, an exploratory risk-stratification algorithm is proposed to facilitate the preoperative identification of patients who may be at increased risk for low postoperative ERAS adherence. Such an approach may facilitate individualized perioperative care and should be evaluated in future prospective studies to determine whether it improves postoperative outcomes.
Supplementary Information
Acknowledgements
Known.
Abbreviations
- ERAS
Enhanced recovery after surgery
- CCI
Charlson comorbidity index
Authors’ contributions
M.C., conceptualization, writing; A.T., review; O.K., review; N.K., data collection; A.H., review; R.R., conceptualization, review, and editing.
Funding
This research received no funding.
Data availability
The datasets analysed during the current study are available from the corresponding author on reasonable request.
Declarations
Ethics approval and consent to participate
This study was approved in November 2023 by the Ethics Committee of Northwestern and Central Switzerland (KEK-Nr. 2023 − 01684). All participants provided written informed consent prior to inclusion in the study.
Consent for publication
Not applicable.
Competing interests
The authors declare no competing interests.
Footnotes
Publisher’s note
Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.
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Associated Data
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Supplementary Materials
Data Availability Statement
The datasets analysed during the current study are available from the corresponding author on reasonable request.