Post-operative neutrophil-lymphocyte ratio predicts complications following colorectal surgery

Introduction: The neutrophil-lymphocyte ratio (NLR) correlates with serial organ dysfunction scores in colorectal surgical patients in critical care units. We hypothesised that the NLR on the first day after an elective colorectal resection would identify patients at increased risk of subsequent complications. Methods: With Ethics Committee approval, 100 patients were recruited to a prospective cohort study. Pre-operative test results and the full blood count on the first post-operative day were noted for all patients. The development of any pre-defined post-operative complications was recorded. Results: Elective colorectal resection was associated with an increase in mean NLR from 3.5 to 11.6 (p < 0.001). Thirty patients developed at least one predefined complication. Patients with an NLR ≥9.3 on the first post-operative day had a significantly greater risk of complications (likelihood ratio 2.12; 95% confidence interval 1.366-3.253). Twenty-two patients had a white cell count ≥11 on the first post-operative day but this was not associated with a significantly increased risk of complications (likelihood ratio 1.94; 95% confidence interval 0.94-3.9). Conclusion: NLR ≥9.3 on the first post-operative day is associated with an increased risk of complications. This simple derivation of routinely available data helps to identify patients at high-risk of complications, allowing targeted preventive measures.