Objective: Various antiviral therapies, including interferon therapy, are being conducted to treat chronic hepatitis C and suppress the onset of hepatocellular carcinoma. However, interstitial pneumonia is beginning to be recognized as one of the adverse reactions of this therapy, and is one of the complications associated with chronic hepatitis. Therefore, we measured the level of KL-6, an interstitial pneumonia marker, in patients with HCV-associated chronic disease, and then determined the possibility of utilizing serum KL-6 as a predictive factor for interstitial pneumonia and the clinical significance of KL-6 in HCV-associated chronic disease.
Subjects and methods: The subjects were 308 patients who were diagnosed with chronic liver disease through biochemical blood tests and abdominal diagnostic imaging. All patients tested positive for either the HCV antibody or HCV-RNA, and those who were suspected of having autoimmune hepatitis were excluded. One hundred eighty-five patients had chronic hepatitis (average age: 56 +/- 14 years), while 123 patients had liver cirrhosis (average age: 64 +/- 9 years). The purpose of the present study was explained to every subject, and informed consent was obtained.
Results: The mean KL-6 level for chronic hepatitis patients without interstitial pneumonia was 283.5 +/- 131.4 U/ml, while that for cirrhotic patients without interstitial pneumonia was significantly higher, at 377.6 +/- 212.1 U/ml (p<0.0001). In addition, with a cut-off value of 500 U/ml, the ratio of high KL-6 for the chronic hepatitis patients was 5.41% (10/185), while that for the cirrhotic patients was significantly higher, at 20.33% (25/123) (p<0.0001). Furthermore, the mean KL-6 level for patients with a serum hyaluronic acid level of less than 100 ng/ml was 258.4 +/- 124.6 U/ml, while that for patients with a serum hyaluronic acid level of 100 ng/ml or above was significantly higher, at 381.0 +/- 197.3 U/ml (p<0.0001).
Conclusion: Although KL-6 is a marker of interstitial pneumonia, the results of the present study suggest that, in HCV-associated chronic disease, this marker reflects hepatic fibrosis better than pulmonary fibrosis.