Patients’ characteristics and morbidity
In total, 108 patients who underwent gastrectomy were enrolled in this study. Of these, 75 were men and 33 were women, with a median age of 71 years. The American Society of Anesthesiologists (ASA) scores, surgical dates, and pathological characteristics are shown in Table 1.
Infectious complications occurred postoperatively in 18 patients (16.6%) (Table 2). Anastomotic leakage was the most commonly observed complication (n = 7), followed by abdominal abscess (n = 4), pancreatic fistula (n = 3), pneumonia (n = 2), cholecystitis (n = 1), and urinary tract infection (n = 1). The median time of infectious disease diagnosis after gastrectomy was 5.8 days.
When the patients’ characteristics were compared between the complication and non-complication groups, there were no significant differences in the patients’ background characteristics, including age, sex, ASA score, or surgical date (Table 3). Regarding surgical factors, only the amount of blood loss was higher in the complication group than in the non-complication group.
The box plot of each biomarker in the perioperative change is shown in Fig. 1a–d. In the 90 patients with no infectious complications, median presepsin levels were 157 pg/mL (25th to 75th percentile: 33–707 pg/mL) and 180 pg/mL (64–1134 pg/mL), 169 pg/mL (56–621 pg/mL), 159 pg/mL (35–792 pg/mL), and 165 pg/mL (48–997 pg/mL), preoperatively and on PODs 1, 3, 5, and 7, respectively. The postoperative values were the same as the preoperative values. In the 18 patients with postoperative infectious complications, the median presepsin levels were 161 pg/mL (25th to 75th percentile: 50–430 pg/mL) and 263 pg/mL (150–1446 pg/mL), 360 pg/mL (211–1097 pg/mL), 450 pg/mL (128–1251 pg/mL), and 380 (76–650 pg/mL), respectively. Preoperative measurements of the presepsin levels were not significantly different between the non-complication and complication groups (p = 0.45). However, presepsin levels on PODs 1, 3, 5, and 7 (p = 0.002, p < 0.0001, p < 0.0001, and p = 0.025, respectively) were significantly higher in the complication group compared to the non-complication group (Table 4).
CRP, WBC, and Neut levels, unlike presepsin, increased and then decreased postoperatively, regardless of infectious complications. CRP and presepsin levels were not significantly different preoperatively between the two groups (p = 0.77), but were significantly higher in the complication group than in the non-complication group on PODs 1, 3, 5, and 7 (p = 0.03, p < 0.0001, p < 0.0001, p = 0.03, respectively). WBC and Neut levels showed no significant differences between the complication and non-complication groups preoperatively (p = 0.24 and 0.45, respectively) and on POD 1 (p = 0.06 and 0.09, respectively), but were significantly higher in the complication group than in the non-complication group on PODs 3 (p = 0.003 and 0.0002, respectively), 5 (p = 0.01 and 0.012, respectively), and 7 (p = 0.01 and 0.01, respectively).
Receiver operator characteristics analysis of the biomarker
We compared the AUC values of presepsin, CRP, WBC, and Neuts, on PODs 1, 3, 5, and 7 between the groups (Fig. 2a–d). The AUC values in the pooled prediction model were comparable to those considered separately. The AUC values were highest for presepsin on PODs 1, 3, and 7 (0.731, 0.89, and 0.77, respectively). On POD 5, the AUC value of presepsin was similar to that of CRP, with a high value > 0.8 (0.86). The AUC values of presepsin were > 0.7 on all days, including on PODs 1, 3, 5, and 7.
Then, the ROC curve was used to calculate the cut-off value for each infectious complication of the PODs (Table 5). On POD 1, the sensitivity and positive predictive value (PPV) of presepsin exceeded 90%, but the specificity and negative predictive value (NPV) were generally as low as 50%. For CRP, WBCs, and Neuts, all values for sensitivity, specificity, the PPV, and NPV were low at 50–70%. On PODs 3, 5, and 7, all the values for sensitivity, specificity, the PPV, and NPV exceeded 80% for presepsin. However, CRP and WBCs showed sensitivity and a PPV that exceeded 80% on PODs 3, 5, and 7, and Neuts showed sensitivity and a PPV exceeding 80% on PODs 5 and 7. For the other parameters, except for presepsin, specificity and NPV did not exceed 80% at any time postoperatively.