Systematic review and meta-analysis of use of serum C-reactive protein levels to predict anastomotic leak after colorectal surgery

Background: Several recent studies have investigated the role of C-reactive protein (CRP) as an early marker of anastomotic leakage following colorectal surgery. The aim of this systematic review and meta-analysis was to evaluate the predictive value of CRP in this setting. Methods: A systematic literature search was performed using MEDLINE, Embase and PubMed to identify studies evaluating the diagnostic accuracy of postoperative CRP for anastomotic leakage following colorectal surgery. A meta-analysis was carried out using a random-effects model and pooled predictive parameters were determined along with a CRP cut-off value at each postoperative day (POD). Results: Seven studies, with a total of 2483 patients, were included. The pooled prevalence of leakage was 96 per cent and the median day on which leakage was diagnosed ranged from POD 6 to 9. The serum CRP level on POD 3, 4 and 5 had comparable diagnostic accuracy for the development of an anastomotic leak with a pooled area under the curve of 0.81 (95 per cent confidence interval 0.75 to 0.80), 0.80 (0.74 to 0.86) and 0.80 (0.73 to 0.87) respectively. The derived CRP cut-off values were 172 mg/l on POD 3, 124 mg/l on POD 4 and 144 mg/l on POD 5; these corresponded to a negative predictive value of 97 per cent and a negative likelihood ratio of 0.26-0.33. All three time points had a low positive predictive value for leakage, ranging between 21 and 23 per cent. Conclusion: CRP is a useful negative predictive test for the development of anastomotic leakage following colorectal surgery.