Study population
Patient recruitment commenced in July 2022 and concluded in March 2023. Among the 150 patients assessed for eligibility, 26 were excluded, leaving a total of 124 patients that were randomly assigned. Following the allocation, both the experimental and control groups experienced six cases of participant loss. Ultimately, 112 participants (56 in the experimental group, 56 in the control group) were included in the analysis. All participants adhered to the prescribed intervention measures. Figure 1 illustrates the flow diagram according to the CONSORT guidelines, including reasons for participant dropout.
Table 1 presents the demographic and clinical characteristics of the patients, including gender, age, body mass index(BMI), diabetes, hypertension, ASA score, smoking history, alcohol consumption history, tumor size, tumor differentiation grade, tumor location, surgical resection method, surgical approach, and preoperative clinical T and N staging. All baseline characteristics of patients in the IN and SEN groups were well-balanced.
Postoperative infections and other complications
Table 2 present the results of postoperative complications. Both groups experienced gastrointestinal intolerance reactions during preoperative enteral nutrition support, but there was no significant difference between the two groups. Compared to patients in the SEN group, patients who received preoperative immunonutrition support had a significantly lower incidence of primary endpoint infectious complications (21.4% vs 37.5%, P=0.040)(Figure 2). The most common infectious complication was pneumonia, with incidence rates of 23.2% in the SEN group and 12.5% in the IN group. There was no statistically significant difference in the incidence of postoperative non-infectious complications between the two groups. The overall incidence of postoperative complications (28.6% vs 44.6%, P=0.049) was significantly lower in the IN group compared to the SEN group, with a statistically significant difference between the two groups.
Postoperative laboratory inflammatory markers
Table 3 and Figure 3 demonstrate that preoperative administration of immunonutrition intervention leads to a reduction in patients' laboratory inflammatory markers. The WBC levels in the IN group were significantly lower than those in the SEN group at preoperative, postoperative day 1, and postoperative day 5 (P=0.011; P=0.019; P=0.034), but there was no significant difference between the two groups on postoperative day 3 (Figure 3A). Moreover, by implementing preoperative immunonutrition intervention, the IN group exhibited significantly lower serum C-reactive protein (CRP) levels than the SEN group at preoperative, postoperative day 1, and postoperative day 3, with statistical significance (P=0.005; P=0.017; P=0.042) (Figure 3B). The IN group also displayed lower IL-6 levels on postoperative day 3 (Figure 3C). However, there were no significant statistical differences observed between the two groups in other laboratory inflammatory markers such as procalcitonin (PCT), IL-1, IL-8, IFN-γ, and TNF-α.
Postoperative laboratory immune markers
As shown in Table 4 and Figure 4, preoperative administration of immunonutrition intervention can also enhance patients' laboratory immune markers. The IN group exhibited significantly higher levels of blood lymphocytes than the SEN group on postoperative day 3 and postoperative day 5 (P=0.016; P=0.011), but no significant differences were observed at preoperative and postoperative day 1 (Figure 4A). Additionally, this study monitored patients' IgA levels and found that the IN group, after 7 days of preoperative immunonutrition intervention, showed significantly higher serum IgA levels compared to the SEN group at preoperative and postoperative day 3, with statistical significance (P=0.048; P=0.027) (Figure 4B). However, no significant statistical differences were observed between the two groups in other laboratory immune markers such as CD4 T lymphocytes, CD8 lymphocytes, CD4/CD8 ratio, IgM, and IgG.
Postoperative recovery and other short-term clinical outcomes of this study
In addition to postoperative complications and infection-related laboratory markers, this study also examined the impact of preoperative administration of immunonutrition on other common short-term clinical outcomes, as shown in Table 5. We found that patients in the IN group had a shorter duration of antibiotic use, with statistical significance (P<0.001), as the results mentioned above demonstrated a lower incidence of infectious complications in the IN group. Furthermore, due to fewer postoperative infections, patients in the IN group had a shorter length of hospital stay (P=0.018) and lower total hospital costs compared to the SEN group (P=0.034). However, in this study, no significant differences were observed between the two groups in terms of surgical duration and intraoperative blood loss. Additionally, the time to first flatus and bowel movement showed no significant differences, which are typically used to evaluate postoperative gastrointestinal functional recovery. One patient in the SEN group was readmitted within 30 days postoperatively due to delayed anastomotic fistula and intra-abdominal infection, requiring continuous irrigation with negative pressure using an infusion-style catheter. No deaths occurred within 30 days postoperatively in either group.
Nutritional status and nutritional markers.
Patients in the IN group experienced an average weight loss of 1.71 kg from preoperative to postoperative day 5, while the SEN group had an average weight loss of 2.25 kg. The IN group exhibited significantly less weight loss during this period, with statistical significance (P=0.043). However, no significant differences were observed between the two groups in terms of albumin, prealbumin, and hemoglobin levels.