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<0.01, I²=0%) and more frequent major postoperative complications (RR=1.33; 95% CI, 1.21-1.45; P<0.01, I²=6%), including cardiovascular morbidity (RR=1.77; 95% CI, 1.45-2.15; P<0.01, I²=0%), infections (RR=1.45; 95% CI, 1.19-1.76; P<0.01, I²=0%), and acute renal dysfunction (RR=2.66; 95% CI, 1.49-4.77; P<0.01, I²=1%).

Conclusion: Preoperative lymphopaenia is associated with death and complications more frequently, independent of the type of surgery.

Prospero registry number: CRD42020190702.

Keywords: complications; death; lymphocyte; lymphopaenia; surgery.

Fig 1

PRISMA flow diagram showing literature search results. Eight studies were used for the meta-analysis. PRISMA, Preferred Reporting Items for Systematic Reviews and Meta-Analysis.

Fig 2

Lymphopaenia and mortality. Funnel plot analysis showed symmetrical shape. CI, confidence interval; M-H, Mantel–Haenszel.

Fig 3

Subgroup analysis for mortality based on different cut-offs for lymphopaenia and type of surgery. Funnel plot analysis showed symmetrical shape for all three groups. CI, confidence interval; M-H, Mantel–Haenszel.

Fig 4

Lymphocyte count and mortality. Funnel plot analysis showed symmetrical shape. CI, confidence interval; sd, standard deviation.

Fig 5

Lymphopaenia and postoperative complications. Funnel plot analysis showed symmetrical shape for all groups. CI, confidence interval; M-H, Mantel–Haenszel.