Inflammatory markers as early predictors of infection after colorectal surgery: the same cut-off values in laparoscopy and laparotomy?

PURPOSE: C-reactive protein and procalcitonin are reliable early predictors of infection after colorectal surgery. However, the inflammatory response is lower after laparoscopy as compared to open surgery. This study analyzed whether a different cutoff value of inflammatory markers should be chosen according to the surgical approach.
METHODS: A prospective, observational study included consecutive patients undergoing elective colorectal surgery in three academic centers. All infections until postoperative day (POD) 30 were recorded. The inflammatory markers were analyzed daily until POD 4. Areas under the ROC curve and diagnostic values were calculated in order to assess their accuracy as a predictor of intra-abdominal infection.
RESULTS: Five-hundred-one patients were included. The incidence of intra-abdominal infection was 11.8%. The median levels of C-reactive protein (CRP) and procalcitonin (PCT) were lower in the laparoscopy group at each postoperative day (p < 0.0001). In patients without intra-abdominal infection, they were also lower in the laparoscopy group (p = 0.0036) but were not different in patients presenting with intra-abdominal infections (p = 0.3243). In the laparoscopy group, CRP at POD 4 was the most accurate predictor of overall and intra-abdominal infection (AUC = 0.775). With a cutoff of 100 mg/L, it yielded 95.7% negative predictive value, 75% sensitivity, and 70.3% specificity for the detection of intra-abdominal infection.
CONCLUSION: The impact of infection on inflammatory markers is more important than that of the surgical approach. Defining a specific cutoff value for early discharge according to the surgical approach is not justified. A patient with CRP values lower than 100 mg/L on POD 4 can be safely discharged.