Summary. We studied the epidemiological, laboratory and histological characteristics of a group of patients with positive antibodies against hepatitis C virus (HCV) as determined by third‐generation enzyme‐linked immunosorbent assay (ELISA), and with indeterminate HCV antibody positivity as established by third‐generation recombinant immunoblot assay (RIBA‐3). The results obtained were compared with those recorded in a group of RIBA‐3‐positive patients. Both groups correspond to blood donors in whom the prevalence of hepatitis C is low. There were no statistically significant intergroup differences in mean age, or in the presence of infection risk factors. RNA positivity was much more frequent in the RIBA‐positive group (71%vs10%;P < 0.05), as was transaminase elevation during the 3 years of follow‐up (54%vs13%;P < 0.05). In 46% of the RIBA‐indeterminate patients the liver biopsy proved normal, or only liver steatosis or minimal changes were detected, while 33% had persistent chronic hepatitis, and 21% showed active chronic hepatitis. A mean Knodell index score of 2.28 was recorded; 50% of the subjects showed no fibrosis, 46% grade 1 fibrosis (fibrous portal expansion), 4% grade 2 fibrosis (bridging fibrosis), and none grade 3 fibrosis (liver cirrhosis). In the RIBA‐positive group, a greater percentage of patients had active chronic hepatitis, a greater Knodell index, and increased‐grade fibrosis. It can be concluded that the RIBA‐3‐indeterminate group is epidemiologically similar to the RIBA‐3‐positive series, although with a lesser prevalence of laboratory test alterations, a lower viral replication index, and more likely to have benign disease – particularly in subjects without viral replication.
