Neutrophil percentage-to-albumin ratio is a new diagnostic marker for spontaneous bacterial peritonitis: a...

The neutrophil percentage-to-albumin ratio (NPAR) is a novel measure of systemic inflammation and infection. Low albumin levels increase the risk of infection, while high neutrophil counts indicate the presence of infection. Spontaneous bacterial peritonitis (SBP) is a serious infection in cirrhotic ascites, and the potential of NPAR in diagnosing SBP is not yet established.

The objective of this study is to determine the diagnostic value of NPAR in identifying SBP.

This prospective multicenter study included 465 patients diagnosed with cirrhotic ascites and SBP according to international guidelines. Demographic, clinical, and laboratory data were collected. The sensitivity and specificity of NPAR values for diagnosing SBP were assessed using the receiver operating characteristic curve.

For SBP diagnosis in the total cohort, NPAR of > 17 had a sensitivity of 85.71%, specificity of 66.67%, and 95% CI (42.1-99.6). In culture-positive SBP, the NPAR at a cut-off > 5.2 had a sensitivity of 85.71%, specificity of 83.33%, and 95% CI (0.709 to 0.979), while in culture-negative SBP, the NPAR at a cut-off > 2.1 had a sensitivity of 92.86%, specificity of 33.33% and CI (0.367 to 0.764). The multivariate analysis revealed that albumin (OR = 2.78, [1.11;3.98], INR (OR = 0.198, [0.066;0.596], creatinine (OR = 0.292, [0.1; 0.81], CRP (OR = 3.18, [1.239;4.52] total leukocytic count (TLC) (OR = 1.97, [1.878; 2.07], platelets (OR = 2.09, [0.99; 2.31] and neutrophil (OR = 3.43, [1.04;3.89] were significantly associated with higher prediction rates for culture positive SBP.

NPAR could be a new, affordable, noninvasive test for diagnosing SBP.