Preoperative lymphopaenia, mortality, and morbidity after elective surgery: systematic review and meta-analysis.

Abstract Background In the general adult population, lymphopaenia is associated with an increased risk for hospitalisation with infection and infection-related death. The quality of evidence and strength of association between perioperative lymphopaenia across different surgical procedures and mortality/morbidity has not been examined by systematic review or meta-analysis. Methods We searched MEDLINE, Embase, Web of Science, Google Scholar, and Cochrane databases from their inception to June 29, 2020 for observational studies reporting lymphocyte count and in-hospital mortality rate in adults. We defined preoperative lymphopaenia as a lymphocyte count 1.0–1.5×109 L−1. Meta-analysis was performed using either fixed or random effects models. Quality was assessed using the Newcastle–Ottawa Scale. The I2 index was used to quantify heterogeneity. The primary outcome was in-hospital mortality rate and mortality rate at 30 days. Results Eight studies met the inclusion criteria for meta-analysis, comprising 4811 patients (age range, 46–91 yr; female, 20–79%). These studies examined preoperative lymphocyte count exclusively. Studies were of moderate to high quality overall, ranking >7 using the Newcastle–Ottawa Scale. Preoperative lymphopaenia was associated with a threefold increase in mortality rate (risk ratio [RR]=3.22; 95% confidence interval [CI], 2.19–4.72; P Conclusion Preoperative lymphopaenia is associated with death and complications more frequently, independent of the type of surgery. Prospero registry number CRD42020190702.