Ascitic calprotectin and lactoferrin for detection of spontaneous bacterial peritonitis: a systematic review and meta-analysis

Background: Spontaneous bacterial peritonitis (SBP) is a common bacterial infection in cirrhotic patients associated with a high mortality rate. Prompt diagnosis and early antibiotic administration are crucial in minimizing adverse outcomes. Although detection of ≥250 polymorphonuclear leukocytes (PMN) in ascitic fluid is the current gold standard to diagnose SBP, consideration for rapid detection with biomarkers is warranted. Methods: A literature search for studies evaluating ascitic calprotectin and lactoferrin for detection of SBP was performed using PubMed, Embase, Scopus, Google Scholar, Cochrane library, and Clinical Trial Registries. Summary sensitivity, specificity, log diagnostic odds ratio (LDOR), and area under the summary receiver operating curve (AUC) were calculated. Results: In total, 12 and 13 studies evaluated ascitic calprotectin and lactoferrin, respectively, for detection of SBP. Summary sensitivity, specificity, and LDOR for calprotectin were 0.942 (95% CI, 0.916, 0.967), 0.860 (95% CI, 0.799, 0.935), and 4.250 (95% CI, 3.504, 4.990), respectively. AUC for calprotectin was 0.91. Summary sensitivity, specificity, and LDOR for lactoferrin were 0.954 (95% CI, 0.930, 0.979), 0.890 (95% CI, 0.836, 0.945), and 4.630 (95% CI, 3.800, 5.452), respectively. AUC for lactoferrin was 0.958. Conclusions: The overall performance of ascitic calprotectin and lactoferrin was substantial, potentially serving as a screening tool or an alternative to manual cell count. However, a variety of manufacturers, cut-off values, and significant heterogeneity between studies should be noted. Point-of-care testing for calprotectin and lactoferrin may resolve disadvantages associated with the current methods. Future studies on this topic are, therefore, needed.