Clinical and pathological characteristics of patients
In this study, the area under the ROC curve (AUC) for PA in predicting severe postoperative complications of MBO was 0.888 (95% CI: 0.832 ~ 0.944). The optimal cutoff point determined by the Youden Index was 89.00, with a corresponding Youden Index of approximately 0.722. This cutoff point exhibited a sensitivity of approximately 94.3% and a specificity of approximately 77.9% (Supplementary Fig. 1). Using this cutoff point, all patients were divided into the super-low PA group (PA<89.0 µg/L, n = 63) and the low PA group (PA ≥ 89.0 µg/L, n = 108). Characteristics of the 171 participants in this study are detailed in Table 1. Among the participants, 113 were male (66.08%), 58 were female (33.92%), with an average age of 63.27 years ± 13.49 years. Diabetes was present in 154 patients (90.06%), and 122 patients had hypertension (71.35%). The tumor was primarily located in the left colon (n = 76, 44.44%), presenting mainly as incomplete obstruction (n = 94, 59.87%), ulcerative type (n = 55, 72.37%), moderately differentiated (n = 74, 83.15%), and tubular adenocarcinoma (n = 76, 64.41%). A few patients experienced intestinal perforation (n = 15, 8.77%), but there was no statistically significant difference between the two groups. In the comparison of the two PA groups, fibrinogen (p = 0.012), albumin(ALB) (<0.001), and total protein (p = 0.009) showed statistical significance. In the PA groups, there were 26 emergency surgery patients (26.90%), with no significant difference between the two groups. The main types of surgery included radical surgery (n = 93, 54.39%) and palliative surgery (n = 78, 45.61%), with palliative surgery comprising palliative tumor resection (n = 26, 15.20%) and simple ostomy (n = 52, 30.41%). The low PA group, compared to the super-low PA group, underwent postoperative chemotherapy (43 vs 36, p = 0.028), had longer postoperative hospital stay (16.19 ± 8.38 vs 12.24 ± 8.7, P = 0.004), total hospital stay (22.67 ± 9.28 vs 18.94 ± 10.01, P = 0.017), and higher hospitalization costs [72604.88(46392.01,98785.77) vs 58462.5(42733.65,77809.62), p = 0.02].
PA is an independent influencing factors for early severe complications (CD ≥ 3) and infectious complications.
In this study, all 171 patients experienced postoperative complications of varying severity, with 95 cases (55.56%) presenting infectious complications. Specifically, 64 cases (37.43%) had incisional infections, 50 cases (29.24%) had pulmonary infections, 20 cases (11.70%) had abdominal infections, and 10 cases (5.85%) developed sepsis (Supplementary Fig. 1). Complications in the low PA group were predominantly classified as CD1 (n = 96, 88.89%), while in the super-low PA group, CD3 complications were more prevalent (n = 26, 41.27%). Overall, there were significant differences between the two groups in different CD classifications of complications (p < 0.001) (Fig. 2 and Supplementary Table 1). Notably, the super-low PA group exhibited a higher rate of CD ≥ 3 complications (n = 32, p < 0.001), indicating that as PA levels decrease, the severity of overall postoperative complications gradually increases (p < 0.001) (Fig. 3). The super-low PA group also had a higher incidence of infectious complications (n = 55,87.30% vs n = 40,37.04%, p < 0.001), with statistically significant differences in various CD classifications between the two groups (p < 0.001), notably higher rates in CD ≥ 3 complications (n = 31,56.36% vs n = 1,2.50%, p<0.001). This suggests that as PA levels decrease, the severity of postoperative infectious complications gradually rises (p < 0.001) (Fig. 3).In this study, both univariate and multivariate logistic regression analyses were conducted on early postoperative severe complications and infectious complications. The results indicate that in the multivariate analysis of all patients, preoperative PA (OR = 0.95, p < 0.001) and preoperative colonic metal stent placement (OR = 10.03, p = 0.015) are significantly associated with early severe complications (CD ≥ 3). Preoperative PA (OR = 0.96, p < 0.001) is significantly associated with infectious complications. However, no significant correlations were found between other indicators and overall complications or infectious complications (Table 2).
PA is identified as an independent influencing factor for overall survival (OS).
In this study, the median follow-up period was 1.58 years, with 19.08% of patients surviving beyond 3 years and a mortality rate of 61.84%. Multifactorial COX regression analysis identified gender,PA levels, pathological staging, surgical approach, and postoperative chemotherapy as independent influencing factors overall survival (OS). Specifically, gender had a hazard ratio (HR) of 0.47 [0.28, 0.78], P = 0.003; tumor history's HR was 1.79 [1.03, 3.12], P = 0.04; PA's HR was 0.99 [0.98, 1], P < 0.001; TNM pathological staging's HR was 2.13 [1.26, 3.61], P = 0.005; surgical approach's HR was 2.49 [1.63, 3.82], P = 0.042; and postoperative chemotherapy's HR was 0.22 [0.13, 0.36], P < 0.001 (Table 3). A multivariate Cox analysis-based line graph for 171 cases of MBO was established, applying it for survival prediction. Gender, PA, TNM staging, tumor history, and postoperative chemotherapy indicators were included in this nomogram (Fig. 4). According to Kaplan-Meier survival curves, patients in the ultra-low PA group had shorter survival than those in the low PA group (P = 0.0016). Factors such as lymph node metastasis, TNM staging, emergency surgery, preoperative complications, infectious complications, early postoperative severe complications, surgical approach, neoadjuvant chemotherapy, and postoperative chemotherapy showed statistically significant differences in survival time (p < 0.05) (Fig. 5).
Compared to traditional nutritional indicators, PA exhibits the highest testing efficiency for early severe postoperative complications in MBO.
In this study, ROC curves were established to compare the predictive ability of PA and other indicators for early postoperative complications (Fig. 6 and Table 4). The AUC values for BMI, ALB, FPR, FAR, and AFR were found to be 0.519, 0.643, 0.871, 0.674, and 0.781, respectively. Notably, AFR exhibited a higher AUC value of 0.888 in predicting early postoperative complications (CD ≥ 3) after MBO surgery, surpassing BMI, ALB, FPR, FAR, and AFR.