Acute phase proteins in the diagnosis and prediction of cirrhosis associated bacterial infections

Abstract Background Bacterial infections are common cause of morbidity and mortality in patients with cirrhosis. The early diagnosis of these infections is rather difficult. Aims To assess the accuracy of acute phase proteins in the identification of bacterial infections. Methods Concentration of C‐reactive protein ( CRP ), procalcitonin ( PCT ), lipopolysaccharide‐binding protein ( LBP ), sCD 14 and antimicrobial antibodies were measured in serum of 368 well‐characterized patients with cirrhosis of whom 139 had documented infection. Clinical data was gathered by reviewing the patients’ medical charts. Results Serum levels of CRP , PCT and LBP were significantly higher in patients with clinically overt infections. Among the markers, CRP – using a 10 mg/L cut‐off value– proved to be the most accurate in identifying patients with infection ( AUC : 0.93). The accuracy of CRP , however, decreased in advanced stage of the disease, most probably because of the significantly elevated CRP levels in non‐infected patients. Combination of CRP and PCT increased the sensitivity and negative predictive value, compared with CRP on its own, by 10 and 5% respectively. During a 3‐month follow‐up period in patients without overt infections, Kaplan–Meier and proportional Cox‐regression analyses showed that a CRP value of >10 mg/L ( P = 0.035) was independently associated with a shorter duration to progress to clinically significant bacterial infections. There was no correlation between acute phase protein levels and antimicrobial seroreactivity. Conclusions C‐reactive protein on its own is a sensitive screening test for the presence of bacterial infections in cirrhosis and is also a useful marker to predict the likelihood of clinically significant bacterial infections in patients without overt infections.