Clinical Significance of Ascitic Fluid Polymorphonuclear Leukocyte Percentage in Patients With Cirrhosis Without Spontaneous Bacterial Peritonitis

INTRODUCTION: Absolute polymorphonuclear leukocyte (PMN) count (PMN-C) ≥250 cells/mm(3) in ascites is the diagnostic hallmark of spontaneous bacterial peritonitis (SBP) and is associated with high morbidity and mortality. However, the clinical significance of ascitic PMN percentage (PMN-%) and PMN-C in the absence of SBP as additional biomarkers for mortality and future incidence of SBP has not been determined. METHODS: This retrospective cohort included adults with cirrhosis undergoing first-recorded paracentesis with initial PMN-C < 250 cells/mm(3) at 2 tertiary medical centers between 2015 and 2020. Patients with prior SBP were excluded. Outcomes were death and SBP development. Cox regression estimated hazard ratios (HRs) for risk of death and SBP development and Akaike information criterion to compare model fit. RESULTS: Three hundred eighty-four adults (73% male, median age 58 years, 67% with alcohol-associated cirrhosis, median PMN-C 14 cells/mm(3) [interquartile range 5–34], and median PMN-% 10% [interquartile range 4–20]) were included in this study. Univariate risk of death increased 10% per 25-unit increase in PMN-C (95% confidence interval 1.01–1.21, P = 0.03) and 19% per 10-unit increase in PMN-% (95% confidence interval 1.06–1.33, P = 0.003) with PMN-% demonstrating better model fit in assessing mortality risk (Akaike information criterion: 1,044 vs 1,048, respectively). In models adjusted for age, chronic hepatitis C virus infection, and Model for End-Stage Liver Disease-Sodium, PMN-% was associated with risk of death (PMN-% 10%–29%, HR 1.17, P = 0.50; PMN-% ≥ 30% group, HR 1.94, P = 0.03; vs PMN-% < 10%) and SBP development (PMN-% 10%–29%, HR 1.68, P = 0.07; PMN-% ≥ 30%, HR 3.48, P < 0.001; vs PMN-% < 10%). DISCUSSION: Our results suggest PMN-% at first paracentesis represents a better biomarker compared with PMN-C for assessing risk of death and future SBP development in patients with PMN-C < 250 cells/mm(3).