Chronic Liver Disease and Streptococcus bovis Endocarditis

Sir—The interesting report by Tripodi and colleagues [1] confirms prior reports of Streptococcus bovis endocarditis being associated with advanced age and involvement of native valves. However, the authors comment that their most interesting finding was a remarkable association with chronic liver disease. Caution appears warranted in concluding that there is such an association. Liver disease was due to viral hepatitis in most patients with S. bovis endocarditis and in all patients with other types of endocarditis. Chronic liver disease due to hepatitis B virus or hepatitis C virus typically develops over decades, so that the rates of liver disease would be expected to be higher among older individuals with these infections. Patients with S. bovis endocarditis were significantly older than those with non–S. bovis endocarditis, with a mean age difference of more than a decade. Although all patients underwent serological testing for hepatitis C and hepatitis B markers, results were not provided for patients without chronic liver disease, so the reader cannot determine whether viral hepatitis infection rates differed overall according to the microbial etiology of endocarditis. In addition, more than three-quarters of patients with S. bovis endocarditis were seen since 2000. Judging on the basis of the reported prevalence of S. bovis endocarditis of 25.3% since 2000, the reported prevalence of 7% in the prior decade, and the numbers of cases, the proportion of cases of endocarditis that were due to S. bovis in the period since 2000 was significantly greater than in the preceding decade. The number of patients with chronic liver disease due to hepatitis C has increased (and will continue to increase) dramatically from 1990 through the first years of the 21st century [2]. Unfortunately, no multivariate analysis of findings that adjusted for age and calendar time was included in the study. Therefore, although the rate of liver disease in this study was very high among patients with S. bovis endocarditis, it is not clear from the data presented that the apparent association is not an artifact of older age and an increasing prevalence of chronic liver disease due to hepatitis in the population at risk.