Natural history of acute hepatitis C.

To study the short- and long-term outcomes of acute hepatitis C, three groups of patients were enrolled. Of 26 patients with acute hepatitis C, 18 (69%) maintained HCV viraemia and 8 had cleared virus naturally at 12 months after the onset. Normalization of ALT was seen in all 8 patients with acute resolving hepatitis, but in only 1 (5%) of the 18 patients with chronic HCV infection (P< 0.001). Changes in liver histology were analysed in 43 patients with acute hepatitis C who underwent repeated liver biopsy. The mean score of the fibrotic stage was 0.9 within 1 year of the onset, and it increased gradually up to 3.5 at 30 years from the onset (0.1 grade/year). The fibrotic stage increased more rapidly in patients aged more than 50 years. In 115 patients, the mean duration between blood transfusion and the diagnosis of HCC increased significantly (P< 0.001) in accordance with increasing age at blood transfusion; 35 +/- 5.3 years in patients aged less than 30 years, 30 +/- 4.9 years in those aged between 30 and 40 years, and 25 +/- 6.8 years in those aged more than 40 years. In conclusion, approximately 70% of patients with acute hepatitis C develop chronic hepatitis. Once patients develop chronic hepatitic fibrosis of the liver, it progresses over several decades, faster in older patients.