In Phase III, all subjects from both groups were followed for six months by biochemical screening, including aminotransferase (ALT) and aspartate aminotransferase (AST). Enzyme assays were performed at least three times, thirty days apart. If aminotransferase activity was persistently abnormal, a liver biopsy was performed. The initial six month follow-up was designed to detect chronic liver disease. Once evidence of chronic liver disease had been established, those patients with chronic liver disease and controls were re-evaluated for evidence of liver disease at six-month intervals for three years from the initial visit.