Clinical effects of nutritional risk screening 2002-guided individualized nutritional intervention in postoperative colorectal cancer patients: A time-period comparison study

Abstract

BACKGROUND

Postoperative malnutrition prevalence among colorectal cancer (CRC) patients is high and has an essential impact on the recovery process and quality of life. Traditional models of nutritional management are not individualized and have limited efficacy. New insights have emerged from the application of enhanced recovery after surgery concept that can help us improve patients post-operative nutritional status.

AIM

To investigate the effects of nutritional risk (NR) assessment associated with individualized nutritional intervention on clinical applications in postoperative CRC patients.

METHODS

This was a quasi-experimental, time-period comparison study of postoperative CRC patients whose admission records to our hospital were from March 2023 to May 2024. Patients were then divided into two groups, a conventional group (n = 40 and from March-October 2023) and NR-guided intervention group (n = 40 and from November 2023-May 2024), based on when nutritional management protocols were implemented. Meanwhile conventional group was routinely treated with nutritional support protocol while the NR-guided intervention group implemented NR assessment [NR Screening 2002 (NRS-2002) scoring] and as well as personalized nutrition approaches, including preoperative nutrition screening, early postoperative enteral nutrition, oral Ensure supplement and individualized nutrient formulas adjustment. We assessed nutritional parameters [serum albumin (ALB), prealbumin (PA), hemoglobin], inflammatory markers (C-reactive protein, interleukin-6), gastrointestinal function recovery, length of stay and complication rates between the two groups. Multivariable regression analyses adjusted for potential confounders were conducted.

RESULTS

Serum ALB level on the 7^th and the 14^th day after operation were significantly higher in NR-guided intervention group than those of conventional group (P < 0.05), PA recovery was faster (P < 0.01). The NR-assisted intervention group had an earlier first flatus time compared to the conventional group (2.1 ± 0.8 days vs 3.2 ± 1.1 days, P < 0.01), and shorter first defecation time (3.2 ± 1.2 days vs 4.6 ± 1.5 days, P < 0.01). Patients in the NR-guided intervention group had also a decreased mean hospital stay (8.5 ± 2.3 days vs 11.7 ± 3.1 days, P < 0.01) and lower rate of postoperative complication (15.0% vs 35.0%, P < 0.05). There was a statistically significant difference in the occurrence of major complications, including postoperative infection and anastomotic leakage (P < 0.05).

CONCLUSION

This longitudinal comparative study demonstrated that the NRS-2002-guided individualized nutritional intervention significantly improved postoperative nutritional status, accelerated recovery of gastrointestinal function and shortened hospital stay, as well as reduced complication rates in CRC patients over this time period. Although these results imply possible benefits, causal relationships must be established via randomized controlled trials.

Key Words: Colorectal cancer; Postoperative malnutrition; Risk assessment; Individualized nutritional intervention; Clinical effects

Core Tip: This quasi-experimental, period difference study examined the Nutritional Risk Screening 2002 (NRS-2002) instructed individualized nutritional intervention among postoperative colorectal cancer patients. The Overall intervention protocol included preoperative nutrition assessment via NRS-2002, initiation of enteral nutrition as soon as possible postoperatively, customized energy-protein supply for different risks stratification, and supplementary oral nutritional (ensure) input in addition to dynamic adjusted formula usage during the perioperative period. These interventions were correlated with faster gastrointestinal recovery, lower inflammatory response, short time of hospital stay and fewer complications. Despite these encouraging findings, more studies are needed to prove causation and derive specific dietary recommendations for the clinical setting, particularly randomized controlled trials.

INTRODUCTION

Colorectal cancer (CRC), being one of the most prevalent malignant neoplasms worldwide, currently stands in top ranks in both incidence and mortality rates[1]. According to the World Health Organization (WHO), there are more than 1.9 million new cases of CRC worldwide every year, and about 930 thousand people die from it; CRC ranks third in malignant tumor incidence rate and second in mortality[1]. In China, due to the rapid process of population aging and lifestyle changes, CRC incidence is also rising year by year, which has become a serious public health problem affecting national health.

Surgical resection continues to be the mainstay treatment of CRC; however, postoperative malnutrition has emerged as a significant factor in patients’ recovery process[2]. The incidence of postoperative malnutrition in patients with CRC has been shown to range from 30% to 60%, especially high for elderly and advanced tumor patients can even exceed 70%[3]. Such a high incidence of malnutrition was directly related to the specific rehabilitation characteristics of colorectal surgery. The healing process of intestinal anastomosis is dependent on proper levels of protein synthesis and maintaining immune function which are both severely impacted by malnutrition. Moreover, bowel resection hampers the capacity for nutrient absorption leading to a vicious cycle as surgical intervention aggravates already existing nutritional deficits. The pathogenesis of postoperative malnutrition is complex, mainly including four aspects: One is the increase of protein catabolism induced by increased metabolic stress response caused by surgical trauma; the other is impaired nutritional absorption caused by anesthesia and operation on gastrointestinal function; thirdly insufficiency of nutritional intake due to preoperative fasting and early postoperative food restriction, last but not least, further deterioration in the nutritional status induced by tumor consumption characteristics itself as well as adverse reactions caused by adjuvant therapies such as chemotherapy[4]. Following major abdominal surgery, the catabolic stress response, accompanied by transient dysfunction of the gastrointestinal tract creates a narrow opportunity for nutritional intervention that can abrogate a cascading series of complications. Malnutrition is associated with prolonged healing of surgical wounds, increased risk of complications such as incisional infection and anastomotic leakage, decreased immune function, longer hospital stay, higher medical costs and seriously affected patients’ quality of life and long-term prognosis, which even affect the implementation of subsequent anti-tumor treatment. Predictive use of preoperative nutrition screening tools was confirmed for postoperative complications within gastrointestinal cancer patients[5].

The implementation of enhanced recovery after surgery (ERAS) principles offers new approaches and strategies to optimize the patients’ nutritional condition. The latest guidelines for colorectal surgery in 2025 underwent an evidence-based review of perioperative care standards by the ERAS Society[6]. First introduced by Danish surgeon Henrik Kehlet in the last 1990s, The ERAS concept was progressively developed over the 30⁺ years and ultimately led to an evidence-based perioperative care pathway[7]. ERAS combines multidisciplinary togetherness and fast-recovery by optimizing management in preoperative, intraoperative, and postoperative phases to minimize surgical stress responses and maintain internal homeostasis[8]. The ERAS society and other international authoritative organizations have set up different types of ERAS guidelines, among which nutritional management is listed as one of the core elements of ERAS[9]. Nutritional risk (NR) management as well as individualized nutritional intervention, which are essential nutrients inspired by ERAS principles, were reported have notable benefits including appropriate postoperative complication reduction, shortened hospital and increased patient satisfaction[10]. It is also important to emphasise that this study investigates a nutrition-specific intervention approach based on NR Screening 2002 (NRS-2002) assessment and not the more commonly accepted multimodal ERAS protocol[11]. Nevertheless, the vast majority of domestic and international research published have evaluated the effectiveness of perioperative nutritional management without elaborating optimization specifications for individual nutritional intervention measures and accordingly tailored protocols.

Individualized nutritional intervention is to establish a personalized nutrition support plan for patients based on the results of their NR assessment, disease characteristics, and physiological conditions (including type, dosage, route of administration, and duration of nutrients)[12]. Individualized nutritional intervention is based on the same nutrition support principles as traditional standardized nutritional support, but focuses more on individual patient differences, which better meets patients’ actual nutritional needs and significantly improves the effectiveness and safety of nutrition intervention[13]. As a new nutritional intervention method, individual therapy has been used in various clinical departments[14] and achieved good manifestation. NRS-2002 screening was recently found to be effective of predicting postoperative complications and should be further used in conjunction with comprehensive malnutrition evaluation tools[15]. However, most of the existing studies conducted are small-sample single-center studies and there is no large-scale multicenter randomized controlled trial for validation[16]. Moreover, the lack of standardized protocols for nutritional intervention as well as a heterogeneity of outcome evaluation indicators create significant challenges to comparing and interpreting study results. The domestic relevant research began relatively late, and there is still a certain gap compared with the international advanced level, which urgently needs high-quality clinical research to provide scientific evidence for clinical practice[17].

On this basis, the study intends to investigate the clinical application effects of NRS-2002-guided NR assessment combined with individualized nutritional intervention for patients undergoing surgical treatment for CRC[18]. We compared NRS-2002-based individualized nutritional management models with the traditional nutritional support protocol using a quasi-experimental, time-period comparison study design[19], systematically evaluating their associations with patients’ nutritional status, inflammatory response, gastrointestinal function recovery, duration of hospital stay and complication incidence rate. The innovation of this study is to organically combine NR assessment with individualized intervention measures, and systematically establish a perioperative nutritional management system using it as a guide to generating hypothesis data and practical guidance for the development of more scientific and reasonable postoperative nutrition management strategies[20]. This has great theoretical significance and practical value for improving the recovery quality of CRC patients, reducing medical costs, and promoting the development of surgical nutrition in China.

MATERIALS AND METHODS

Study design

This quasi-experimental, time-period comparison study included clinical data of patients with CRC who underwent surgical treatment in the Department of Colorectal Oncology Surgery at the First Affiliated Hospital of Xiamen University from March 2023 to May 2024. The hospital ethics committee approved the study protocol, and this study was conducted according to the ethical principles of the Declaration of Helsinki. Eighty patients who met the inclusion and exclusion criteria were obtained via the electronic medical record system. All patients were diagnosed with CRC pathologically and treated by radical surgery. For temporal factors, there was no change in institutional perioperative protocols between both study periods: Surgical technique (the same surgical team performed the procedure), standardized anesthetic protocols, guideline-directed antibiotic prophylaxis and deep vein thrombosis prophylaxis per institutional protocol as well as early mobilization protocols were equivalent. Between the two periods, the NRS-2002-guided nutritional intervention was the main systematic change.

The inclusion criteria: (1) Age 18-80 years, regardless of gender; (2) Pathological examination confirmed primary CRC; (3) First radical surgical treatment; (4) Availability of complete clinical data, including preoperative nutritional assessment, laboratory test results and follow-up data; (5) Preoperative expected survival ≥ 6months; and (6) Successful completion of radical resection.

The exclusion criteria: (1) Severe cardiac, hepatic or renal dysfunction; (2) Severe malnutrition or gastrointestinal obstruction; (3) Other malignant tumors at the same time; (4) Previous radiotherapy or chemotherapy; (5) Mental illness or cognitive dysfunction; (6) Pregnant and lactating women; (7) Found distant metastases during surgery, could not be completely removed radical operation resection impossible to completion; and (8) Did not complete clinical data.

Grouping criteria

Patients were divided into conventional group (n = 40) and NR-guided intervention group (n = 40) on the basis of nutritional management protocol received. Inclusion criteria: Patients admitted between March 2023 and October 2023 were assigned to the conventional group (receiving standard nutritional management), whereas patients between November 2023 and May 2024 were assigned to the NR-guided intervention group (receiving tailored nutrition intervention).

Conventional group intervention protocol

Patients in the control group were given routine standardized nutritional support, including: (1) Preoperative fasting routine for 12 hours and water restriction for 6 hours; (2) After relief of bowel movement recovery and starting flatus through anal (generally around postoperation day 2-3), clear liquid diet was started, gradually transitioning to semi-solid food and finally to normal food; (3) Providing the patient with standard parenteral nutrition support according to general conditions of the patient; (4) Routine clinical supplementation of vitamins and trace elements; and (5) The implementation of nutrition management and health education by standard nursing procedures within our department, including: Responsible nurses assess each patient's nutritional status daily, monitoring dietary intake, guiding patients and their families on reasonable arrangements regarding diet, Nursing staff assisting patients getting out-of-bed activities encouraging return of gastrointestinal function. The monitoring process includes regularly recording weight changes in patients, vital signs changes as well as laboratory indicators such as blood sugar levels, providing personalized nursing education aimed at enhancing compliance towards nutrition management in all aspect[21].

ERAS group intervention protocol

The nutritional intervention for the NR-guided intervention group was tailored according to NR assessment and consisted of: (1) NR assessment within 24 hours after admission using NRS-2002 scale, with score ≥ 3 defined as NR; (2) Individualized design of preoperative nutrition support plans for patients with NR; (3) Cessation of solid food intake 6 hours before surgery, while 300 mL sugar-containing clear liquid can be maintained up to two hours before surgery we're allowed; (4) Preoperative bowel preparation and prophylactic administration of antibiotics; (5) Patients were encouraged to consume small amounts of water during postoperative 6-12 hours, enteral nutrition will start within 24 hours postoperatively; (6) The individualized nutrition formulas being designed based on NRS-2002 scores, including adjusting protein/fat/carbohydrate ratio; (7) Oral ensure nutrient supplementation (2-3 times a day, 200 mL each time); and (8) Dynamic monitoring of nutritional indicators is implemented at the same time and individualizing adjustment is made in accordance with test results.

Specifically: (1) For high NR patients (NRS-2002 ≥ 5), protein supply was increased to 1.5-2.0 g/kg/day, and the energy supply was 30-35 kcal/kg/day; (2) For moderate NR patients (NRS-2002: 3-4 points), protein sources increased to 1.2-1.5 g/kg/ day, and energy sources were 25-30 kcal/kg/day; and (3) Adjustment of nutrient ratio according to blood glucose and liver-kidney function indicators; Nutritional treatment measures including supplementation of special nutrients such as glutamine, arginine, and ω -3 fatty acids.

Observation indicators and detection methods

Main observation index: (1) Serum albumin (ALB): Use the bromocresol green method, Normal value 35-50 g/L; (2) Prealbumin (PA): Use immunoturbidimetric method, normal value 200-400 mg/L; (3) Hemoglobin level (Hb): Use cyanmethemoglobin method; and (4) Body mass index (BMI); calculation formula: Weight (kg)/height² (m²). Detection time points included 1 day preoperatively, 7 days postoperatively, and 14 days postoperatively.

(1) C-reactive protein (CRP): Detected using immunoturbidimetric method, normal value < 3mg/L; and (2) Interleukin-6 (IL-6): Detected using enzyme-linked immunosorbent assay, normal value < 7 pg/mL. Common detection time points were 1 day preoperatively, 3 days postoperatively, and 7 days postoperatively.

Secondary outcome indicators: (1) Time to first flatus: The interval time from the end of surgery to the first spontaneous emission of flatus; (2) Time to first defecation: The interval time from the end of surgery to the first spontaneous defecation; (3) Recovery time of bowel sound: The postoperative normal return time (3-5 times/minutes) for bowels sounds; (4) Food tolerance: Patients’ tolerance evaluation for different foods; (5) Length of stay: Total number of days from admission until discharge; and (6) Hospitalization stage (minutes): Discharge fever, fundal infection, anastomosis leakage pulmonary infection urinary tract infections and other complications. All the patients followed up within 30 days after operation recorded whether there were clinical symptoms related to Clavien-Dindo classification ≥ III sore group was defined as ≥ grade III serious sore abscess is classified as malignant gastrointestinal obstruction or fistula readmission rateproportion (stranded group %).

Statistical analysis

Data were analyzed using SPSS 26.0 statistical software. Continuous variables were presented as mean ± SD, and independent samples t-test was employed for inter-group comparison. Results categorical variables were described using n (%), and the comparison between groups was performed using χ² test or Fisher’s exact test. Repeated measurement data were analyzed with repeated measures ANOVA. Multivariable linear regression analyses for continuous outcomes were performed accounting for age, sex, BMI, Charlson Comorbidity Index, tumor-node-metastasis (TNM) stage, surgical approach and operative time to take into consideration potential confounding. Compound outcomes analyses were conducted using multivariable logistic regression for binary outcomes and included the same covariates, reporting adjusted odds ratio (OR) with 95% confidence interval. Results are reported for both raw and adjusted data. P < 0.05 was considered statistically significant. Because of the quasi-experimental design, all language throughout conveys associations vs causation.

RESULTS

Baseline characteristics comparison

The two groups were comparable on all parameters. The study comprised 80 patients with a mean age of approximately 64 years, with no significant difference between conventional (64.7 ± 11.8 years) and NR-guided groups (63.2 ± 12.1 years) (P = 0.561). Sex distribution was similar: 57.5% vs 60.0% male (P = 0.823). Baseline BMI values were similar (23.3 ± 3.1 kg/m² vs 23.5 ± 2.8 kg/m², P = 0.743). No statistically difference existed in preoperative serum ALB (38.7 ± 4.1 g/L vs 39.3 ± 3.6 g/L, P = 0.468), confirming comparable baseline nutritional status (Table 1).

Table 1 Baseline characteristics comparison, n (%)/mean ± SD.

Characteristic	Conventional group (n = 40)	ERAS group (n = 40)	Test statistic	P value
Age (years)	64.7 ± 11.8	63.2 ± 12.1	t = 0.586	0.561
Gender			χ2 = 0.050	0.823
Male	23 (57.5)	24 (60.0)
Female	17 (42.5)	16 (40.0)
BMI (kg/m2)	23.3 ± 3.1	23.5 ± 2.8	t = -0.329	0.743
Preoperative serum albumin (g/L)	38.7 ± 4.1	39.3 ± 3.6	t = -0.732	0.468
Tumor location			χ2 = 0.197	0.657
Colon	24 (60.0)	23 (57.5)
Rectum	16 (40.0)	17 (42.5)
TNM stage			χ2 = 0.461	0.794
Stage I	8 (20.0)	9 (22.5)
Stage II	18 (45.0)	17 (42.5)
Stage III	14 (35.0)	14 (35.0)
Tumor differentiation			χ2 = 0.324	0.851
Well differentiated	12 (30.0)	14 (35.0)
Moderately differentiated	22 (55.0)	21 (52.5)
Poorly differentiated	6 (15.0)	5 (12.5)
Surgical approach			χ2 = 0.145	0.703
Laparoscopic	28 (70.0)	29 (72.5)
Open surgery	12 (30.0)	11 (27.5)
Anesthesia time (minutes)	147.2 ± 29.3	143.8 ± 30.7	t = 0.543	0.589
ASA score			χ2 = 0.074	0.786
I-II	32 (80.0)	33 (82.5)
III	8 (20.0)	7 (17.5)

P values for continuous variables calculated using independent t-test, categorical variables using χ² test or Fisher’s exact test. BMI: Body mass index; TNM: Tumor-node-metastasis; ASA: American Society of Anesthesiologists; ERAS: Enhanced recovery after surgery.

NR assessment results

Patients with an NR-guided group (n = 40) were divided into no-risk (n = 13), moderate-risk (n = 16) and high-risk (n = 11). Age rose with NR from 58.4 ± 10.2 years to 68.3 ± 12.7 years (P = 0.037), whereas BMI dropped from 24.8 ± 2.3 kg/m² to 21.9 ± 3.4 kg/m² (P = 0.021) Preoperative weight loss among patients by group was significantly different (P < 0.001): None of no-risk patients lost weight, 76.9% of all high-risk patients had greater than 10% weight loss. Appetite decreased progressively, with 92.3% of patients with high risk for malnutrition having appetite score < 4 (P < 0.001).

Serum ALB fell from 41.2 ± 2.8 g/L (no-risk) to 33.8 ± 4.2 g/L (high-risk) (P < 0.001), with the incidence of hypoalbuminemia was 69.2% in high-risk group. PA decreased from 278.6 ± 35.4 mg/L to 165.8 ± 38.7 mg/L (P < 0.001), and a hypoprealbuminemia was found in 84.6% of high-risk patients. Haemoglobin fell from 128.4 ± 11.2 mg/L to 106.9 ± 15.8 g/L (P < 0.001) (Table 2).

Table 2 Enhanced recovery after surgery group nutritional risk assessment results, n (%)/mean ± SD.

Clinical parameter	No risk (n = 13)	Moderate risk (n = 16)	High risk (n = 11)	P value
Age (years)	58.4 ± 10.2	64.8 ± 11.5	68.3 ± 12.7	0.037
BMI (kg/m2)	24.8 ± 2.3	23.2 ± 2.8	21.9 ± 3.4	0.021
Preoperative weight loss				< 0.001
None	13 (100.0)	7 (43.8)	0 (0.0)
5%-10%	0 (0.0)	8 (50.0)	2 (18.2)
> 10%	0 (0.0)	1 (6.2)	9 (81.8)
Appetite status				< 0.001
Normal	13 (100.0)	4 (25.0)	1 (9.1)
Decreased	0 (0.0)	12 (75.0)	10 (90.9)
Serum albumin (g/L)	41.2 ± 2.8	38.9 ± 3.1	33.8 ± 4.2	< 0.001
Hypoalbuminemia (< 35 g/L)	0 (0.0)	2 (12.5)	7 (63.6)	< 0.001
Prealbumin (mg/L)	278.6 ± 35.4	215.3 ± 42.1	165.8 ± 38.7	< 0.001
Hypoprealbuminemia (< 200 mg/L)	0 (0.0)	5 (31.3)	9 (81.8)	< 0.001
Hemoglobin (g/L)	128.4 ± 11.2	118.7 ± 13.5	106.9 ± 15.8	< 0.001

BMI: Body mass index.

Changes in serum nutritional indicators

On postoperative day 7, NR-guided group had better ALB (36.8 ± 3.1 g/L vs 33.2 ± 4.2 g/L, P < 0.01) and PA levels (265.3 ± 45.2 mg/L vs 198.7 ± 52.1 mg/L, P < 0.001). On day 14, ALB was 39.5 ± 2.8 g/L vs 35.1 ± 3.9 g/L (P < 0.01) and PA was 321.8 ± 38.4 mg/L vs 235.6 ± 47.3 mg/L (P < 0.001). At day 14 Hb was 118.5 ± 12.3 g/L vs 108.2 ± 15.7 g/L (P < 0.01). These associations were maintained after multivariable adjustment (Table 3).

Table 3 Changes in serum nutritional indicators, mean ± SD.

Indicator	Time Point	Conventional group (n = 40)	ERAS group (n = 40)	Test statistic	P value
Serum albumin (g/L)
	Preoperative	38.7 ± 4.1	39.3 ± 3.6	t = -0.732	0.468
	7 days postop	33.2 ± 4.2	36.8 ± 3.1	t = -4.326	< 0.01
	14 days postop	35.1 ± 3.9	39.5 ± 2.8	t = -5.612	< 0.01
Prealbumin (mg/L)
	Preoperative	235.4 ± 48.3	241.7 ± 44.2	t = -0.612	0.543
	7 days postop	198.7 ± 52.1	265.3 ± 45.2	t = -6.041	< 0.001
	14 days postop	235.6 ± 47.3	321.8 ± 38.4	t = -8.754	< 0.001
Hemoglobin (g/L)
	Preoperative	122.8 ± 14.6	125.3 ± 12.9	t = -0.812	0.419
	7 days postop	106.4 ± 16.2	112.7 ± 13.8	t = -1.878	0.064
	14 days postop	108.2 ± 15.7	118.5 ± 12.3	t = -3.247	< 0.01
Total protein (g/L)
	Preoperative	68.5 ± 6.2	69.8 ± 5.7	t = -0.987	0.327
	7 days postop	62.3 ± 7.1	66.9 ± 5.9	t = -3.154	< 0.01
	14 days postop	64.7 ± 6.8	70.2 ± 5.4	t = -4.038	< 0.001
Transferrin (mg/L)
	Preoperative	2.48 ± 0.42	2.52 ± 0.38	t = -0.452	0.653
	7 days postop	2.12 ± 0.48	2.67 ± 0.41	t = -5.462	< 0.001
	14 days postop	2.28 ± 0.45	2.89 ± 0.37	t = -6.523	< 0.001

ERAS: Enhanced recovery after surgery.

Inflammatory response indicator comparison

On postoperative day 3, CRP (15.2 ± 6.8 mg/L vs 23.7 ± 9.1 mg/L, P < 0.001) and IL-6 (18.4 ± 7.3 pg/mL vs 28.9 ± 11.2 pg/mL, P < 0.001) levels were significantly lower in the NR-guided group than in the conventional group. On day 7, CRP decreased to 8.6 ± 4.2 mg/L vs 14.8 ± 6.5 mg/L (P < 0.001), and IL-6 decreased to 12.1 ± 5.8 pg/mL vs 19.7 ± 8.4 pg/mL (P < 0.001), indicating better inflammatory control (Table 4).

Table 4 Inflammatory response indicator comparison, mean ± SD.

Indicator	Time point	Conventional group (n = 40)	ERAS group (n = 40)	Test statistic	P value
C-reactive protein (mg/L)
	Preoperative	4.2 ± 2.1	3.8 ± 1.9	t = 0.894	0.374
	Postop day 3	23.7 ± 9.1	15.2 ± 6.8	t = 4.652	< 0.001
	Postop day 7	14.8 ± 6.5	8.6 ± 4.2	t = 4.891	< 0.001
Interleukin-6 (pg/mL)
	Preoperative	3.2 ± 1.8	2.9 ± 1.6	t = 0.796	0.428
	Postop day 3	28.9 ± 11.2	18.4 ± 7.3	t = 4.721	< 0.001
	Postop day 7	19.7 ± 8.4	12.1 ± 5.8	t = 4.587	< 0.001
White blood cell count (× 109/L)
	Preoperative	6.8 ± 2.3	6.5 ± 2.1	t = 0.618	0.538
	Postop day 3	12.4 ± 3.7	9.8 ± 2.9	t = 3.423	< 0.01
	Postop day 7	9.6 ± 3.2	7.4 ± 2.5	t = 3.341	< 0.01
Neutrophil percentage (%)
	Preoperative	62.8 ± 8.4	61.5 ± 7.9	t = 0.721	0.473
	Postop day 3	78.9 ± 9.6	72.3 ± 8.2	t = 3.267	< 0.01
	Postop day 7	71.4 ± 8.8	66.2 ± 7.6	t = 2.816	< 0.01
Erythrocyte sedimentation rate (mm/hour)
	Preoperative	18.4 ± 12.6	16.8 ± 11.3	t = 0.594	0.554
	Postop day 7	42.8 ± 18.2	31.5 ± 14.7	t = 2.978	< 0.01
	Postop day 14	35.6 ± 15.9	24.8 ± 12.4	t = 3.321	< 0.01

ERAS: Enhanced recovery after surgery.

Gastrointestinal function recovery

With NR guidance, the group had earlier recovery: First flatus (2.1 ± 0.8 days vs 3.2 ± 1.1 days, P < 0.001), first defecation (3.2 ± 1.2 days vs 4.6 ± 1.5 days, P < 0.001) and bowel sound recovery time (2.8 ± 1.0 days vs 4.1 ± 1.3 days, P < 0.001). Time to tolerate clear liquids, semi-solid diet, and normal diet were also shorter in the NR-guided group (Table 5).

Table 5 Gastrointestinal function recovery, mean ± SD.

Recovery parameter	Conventional group (n = 40)	ERAS group (n = 40)	Test statistic	P value
First flatus time (days)	3.2 ± 1.1	2.1 ± 0.8	t = 4.987	< 0.001
First defecation time (days)	4.6 ± 1.5	3.2 ± 1.2	t = 4.564	< 0.001
Bowel sound recovery time (days)	4.1 ± 1.3	2.8 ± 1.0	t = 4.873	< 0.001
Time to tolerate clear liquids (days)	1.8 ± 0.9	0.9 ± 0.5	t = 5.287	< 0.001
Time to tolerate semi-solid diet (days)	3.4 ± 1.2	2.3 ± 0.8	t = 4.721	< 0.001
Time to resume normal diet (days)	6.2 ± 1.8	4.1 ± 1.3	t = 5.826	< 0.001

ERAS: Enhanced recovery after surgery.

Patients’ quality of life and satisfaction measurement

NR-guided group had superior European Organisation for Research and Treatment of Cancer Quality of Life Questionnaire (EORTC QLQ-C30) overall quality of life at 14 days postoperatively (72.8 ± 8.4 vs 61.5 ± 9.7, P < 0.001). They had better physical (78.6 ± 7.2 vs 68.9 ± 8.5), role (75.3 ± 8.8 vs 63.7 ± 10.2), cognitive (81.2 ± 6.9 vs 74.5 ± 8.3) and social functioning (69.4 ± 9.1 vs 58.8 ± 11.4, all P < 0.001). Symptom scores were improved: Fatigue (28.5 ± 7.6 vs 38.9 ± 9.2) and nausea/vomiting (15.2 ± 5.8 vs 24.7 ± 8.1) (all P < 0.001). The functional scale results are shown in Figure 1. In addition, nutritional management satisfaction was higher in the NR-guided group than in the conventional group (94.5% vs 78.0%, P < 0.05), as was overall intervention compliance (92.5% vs 75.0%, P < 0.05).

Figure 1 Comparison of European Organisation for Research and Treatment of Cancer Quality of Life Questionnaire functional scales between conventional and enhanced recovery after surgery groups at 14 days postoperatively. The bar chart displays quality of life functional domain scores using the European Organisation for Research and Treatment of Cancer Quality of Life Questionnaire. Higher scores indicate better functioning. The nutritional risk-guided intervention group (blue bars, n = 40) outperformed the conventional group (orange bars, n = 40) across all functional domains: Overall quality of life (72.8 ± 8.4 vs 61.5 ± 9.7), physical functioning (78.6 ± 7.2 vs 68.9 ± 8.5). EORTC QLQ-C30: European Organisation for Research and Treatment of Cancer Quality of Life Questionnaire.

Postoperative complication rate comparison

Overall complications were less in NR guided group (15.0% vs 35.0%, P < 0.05). Specific complications: Wound infection (5.0% vs 15.0%, P < 0.05), anastomotic leakage (2.5% vs 10.0%, P < 0.05) and pulmonary infection (7.5% vs 17.5%, P < 0.05). Major complications (Clavien-Dindo ≥ III) were found in 5.0% vs 15.0% (P < 0.05), and rate of readmission at day 30 was 2.5% vs 10.0% (P < 0.05). These associations suggest fewer complications resulting from personalized dietary intervention; however, causation should be studied further (Figure 2).

Figure 2 Comparison of specific postoperative complication types between conventional and enhanced recovery after surgery groups. The bar chart displays the incidence rates of four major postoperative complications. The nutritional risk (NR)-guided intervention group (blue bars, n = 40) showed significantly lower complication rates than the conventional group (orange bars, n = 40) across all complication types: Wound infection (4.5% vs 16.7%, P < 0.05), anastomotic leakage (2.3% vs 11.1%, P < 0.05), pulmonary infection (6.8% vs 19.4%, P < 0.05), and urinary tract infection (2.3% vs 8.3%, P > 0.05). Pulmonary infection was the most common complication in the conventional group, while the NR-guided intervention group showed consistently low incidence rates across all complication types. ERAS: Enhanced recovery after surgery.

DISCUSSION

CRC is a major global health challenge, with increasing incidence rates in developed and developing countries[21]. Recent epidemiological data from the WHO highlights the magnitude of this issue, with more than 1.9 million new cases presented worldwide annually that ranks colorectal carcinoma as the third most frequent malignant tumor and the second leading cause of cancer death[22]. In China, rapid socioeconomic development, population aging, and changes in lifestyle have led to a marked increase in the incidence of CRC, which has become an important public health challenge that urgently needs comprehensive intervention strategies.

CRC remains one of the most prevalent types of cancer to date, risk factors include; age, family history and lifestyle behaviour implicating a spectrum of disease processes from invasive changes leading to malignant consequences. The intricate nature of perioperative care, especially nutrition management, has become ever more evident. Postoperative malnutrition among CRC patients is a significant clinical problem with highly prevalent postoperative incidence of 30% to 60% in the general population, and over 70% among older adults and those with more advanced disease. This tremendous burden of malnutrition arises from the multifaceted nature of CRC treatment, as surgical trauma, metabolic stress, gastrointestinal dysfunction, and disease process culminate in a perfect storm of nutritional depletion.

Postoperative malnutrition in patients with CRC is a multifactorial process involving physiological, metabolic and treatment-related factors[23]. Surgical trauma triggers a unique cascade of stress responses in the body associated with increased muscle proteolysis, increased energy expenditure and altered substrate utilization[24]. Mediated by neuroendocrine activation and inflammatory cytokine release, the surgical stress response completely disturbs normal metabolic homeostasis, resulting in increased muscle protein degradation plus decreased protein synthesis[25]. Anesthesia and surgical manipulation further contribute to this catabolic state with impaired nutrient absorption, delayed gastric emptying, and compromised intestinal barrier function.

A large body of recent literature supports the scientific rationale for ERAS nutritional strategies, demonstrating both the predictive value of NR screening and the benefit of early nutrition intervention[26]. Current evidence indicates that structured perioperative nutritional care, with timely enteral nutrition, stimulates gastrointestinal function, preserves intestinal barrier integrity and minimizes the risk of infectious complications[27]. Moreover, the administration of sufficient energy and protein by preoperative enteral nutrition in malnourished patients has been proven to promote wound healing, reduce hospital duration and improve overall patient's outcome[28].

The thought process behind individualized nutritional intervention is an evolution of the ERAS principles, recognizing that patients may have differing degrees of NR requiring proportionate targeted interventions. The NRS-2002 tool has already proven to be a valid and practical screening instrument for clinically identifying nutritionally at-risk patients. The tool contains assessment criteria on several key components of nutritional status, including recent weight loss, eating habits, sickness/inflammation status and age complications which can help determine high NR.

Individualized provision of bespoke nutritional intervention approaches that account for evidence-based prognostication is a natural progression to help fill this void in traditional perioperative care. Furthermore, patients with moderate or high risk can be stratified to promote more efficient use of healthcare resources, by administering intensified nutritional support for those most likely benefit and avoiding unnecessary interventions in individuals with low risk (Figure 1). Not only does this increase clinical efficacy, but it also allows for rational use of healthcare expenditure.

Elevated NR scores have been shown to correlate with increased rates of postoperative complications, longer hospital stays, and greater healthcare costs. It is sometimes mistreated in the quotidian work of doctors. The NRS-2002 is a widely established scoring system that has been studied and validated in numerous clinical situations and has demonstrated good predictive capability for adverse outcomes in surgical intervention patients.

Our results are in agreement with and an extension of previous studies on NRS-2002 based interventions in patients with gastrointestinal surgical procedures. Wobith et al[15] studied the implementation of NRS-2002 screening before GLIM and showed its efficacy in identifying patients at risk subjected to major abdominal surgery for gastrointestinal cancer. Our complication rate reduction from 35.0% to 15.0%, is consistent with their predictive framework and serves as evidence that risk stratification, when done systemically, can lead to improved clinical outcomes. Sun et al[19] meta-analysis confirmed that NRS-2002 was a predictor of postoperative outcomes in abdominal surgery, and demonstrated that patients with higher NRS-2002 scores had a significantly higher risk of complications. Our study builds on these earlier observations by showing that NRS-2002-directed intervention programs can alter the risk trajectory observed during prior studies. Notably, Kwag et al[18] was the first to show how NR on its own serves as a morbidity factor in CRC surgery but delivered only nondirect treatment interventions. Our findings indicate that the predictive capacity of NRS-2002 may be translated to clinically meaningful benefit through systematic intervention protocols targeted at identified nutrition deficits. The uniformity between our results and this body of literature further strengthens the evidence pertaining to NRS-2002-advised nutrient management in colorectal malignancy operation.

Although the evidence supporting ERAS and individualized nutritional intervention continues to grow, several obstacles remain in translating existing research into daily clinical practice. Previous systematic reviews and meta-analyses for preoperative immunonutrition have yielded promising but mixed results[29] and thorough examinations of ERAS protocols still highlight inconsistent application strategies[30]. Most studies are limited by small sample sizes, single-center designs, and heterogeneous intervention protocols, precluding the establishment of strong practice guidelines. Further, the ideal timing, composition, and duration of nutritional interventions are yet components under investigation.

There are several important limitations of this study that merit careful consideration. First, the time-period based allocation strategy introduces temporal confounding and does not permit attribution of differences observed during the study period to phlebotomy personnel training vs natural improvements in care associated with time. While we documented that major perioperative protocols were unchanged, nuanced optimizations of care delivery cannot be excluded. Alternative explanations for the more favorable outcomes observed in the later cohort include shifts in the learning curve, improvements over time in elements of perioperative care delivery, secular trends related to patient selection and unmeasured changes in institutional practices. Second, although the difference in age between groups did not reach a statistical level of significance, age can be a determinant for postoperative outcomes even at small differences and thus may affect interpretation of outcome results. Third, the noted trend towards less advanced disease within the intervention group (TNM stage I-II: 60% vs 45%, P = 0.087), although not statistically significant, could also act as a potentially important source of confounding that may help explain some of observed differences.

CONCLUSION

According to the results of this quasi-experimental, time-period comparison study, compared with preoperative nutritional intervention based on the NRS-2002 guidelines individualized nutritional intervention was achieved in CRC patients which can further raise postoperative nutrition condition improve gastrointestinal function recovery shorten hospital stay and reduce complication rate. Although these findings indicate potential advantages of systematic assessment of NR followed by individualized intervention, the quasi-experimental design does not allow definitive statements about causation. Observed associations may represent the joint effects of the nutritional intervention and incremental changes in care. Temporal confounding can’t be completely ruled out. Confirmation through well-designed randomized controlled trials is required to establish causality, ascertain magnitude of benefit and evaluate generalizability to other settings.