Antipyrine clearance and response to interferon treatment in patients with chronic active hepatitis C

To determine whether hepatic metabolic function affects the response to interferon treatment, we measured antipyrine clearance (APC) in 85 patients with chronic active hepatitis C and compared the results with treatment outcome. Among 55 patients who responded to interferon by normalization of alanine transaminase (ALT), median APC before treatment was 0.47 (range, 0.12 to 0.98; normal range, 0.34 to 1.02 mL/min/kg body wt), a value that was significantly greater than in 30 nonresponders (0.23; 0.08 to 0.67 mL/min/kg body wt, P < .001). APC was closely associated with response to interferon. The response rate among cases with values > 0.25 mL/min/kg body weight was 79%, the same as in cases without cirrhosis. Cases without cirrhosis and with APC of > 0.25 mL/min/kg body weight had an 85% chance of responding to interferon; this was unlikely a simple reflection of histological activity, because the correlation with Scheuer score was poor in this subgroup (r = -.31, P < .05). A second, independent group of 43 patients was used to test the predictive value of APC (using 0.25 mL/min/kg body wt as a cut-off) for response to interferon treatment. In this group, APC correctly predicted positive response to interferon in 75% of cases. APC was also used to measure the effects of treatment on hepatic metabolic function. Regardless of outcome, there was no change in APC at the end of a 6-month course of interferon treatment. Six months later, however, improvement in APC (14%; P < .05) was evident among responders but not in those who had failed to respond to interferon.(ABSTRACT TRUNCATED AT 250 WORDS)