The neutrophil-lymphocyte count ratio as a diagnostic marker for bacteraemia: A systematic review and meta-analysis

Background: Bacteraemia is a common cause of increased morbidity and mortality in critically ill patients, but its early diagnosis and identification are complicated. The neutrophil-lymphocyte count ratio (NLCR) has been suggested as a useful indicator for the diagnosis of bacteraemia. We performed this meta-analysis to investigate the diagnostic accuracy of the NLCR for bacteraemia.

Methods: We searched the PubMed, Embase, Web of Science, and Cochrane Library databases for this meta-analysis. We calculated individual and pooled sensitivities and specificities. I² statistics and Cochran's Q test were used to evaluate heterogeneity, and the cause of heterogeneity was explored with sensitivity analyses.

Results: In total, 8 of 1086 eligible articles were included in the present meta-analysis. The pooled analyses revealed that the diagnostic accuracy of the NLCR in terms of its bacteraemia sensitivity was 0.723 [95% CI: 0.660, 0.777], and its specificity was 0.596 [95% CI: 0.556, 0.634]. The area under the summary receiver operating characteristic curve was 0.69 [95% CI 0.65-0.73].

Conclusion: The NLCR is an easy-to-collect marker for bacteraemia. However, the NLCR is inadequate, and only a combination of multiple biomarkers will improve its diagnostic accuracy for bacteraemia.