http://www.hivandhepatitis.com/hep_c/news/2010/0611_2010_a.html
Sustained virological response (SVR) to hepatitis C treatment is usually defined as continued undetectable HCV viral load 24 weeks after completion of therapy. Michelle Martinot-Peignoux and colleagues from France evaluated whether assessment of serum HCV RNA 12 weeks after the end of treatment was as relevant as 24 weeks for determining SVR.
The investigators analyzed sustained treatment outcomes among 573 chronic hepatitis C patients who received pegylated interferon (Pegasys or PegIntron) plus ribavirin and had an end-of-treatment virological response. Viral load was measured using a sensitive TMA assay with a lower limit of 5-10 IU/mL. Viral relapse was defined as reappearance of detectable HCV-RNA between the end of treatment and post-treatment week 24.
Results All 573 participants had undetectable HCV RNA at the end of treatment.
At 12 weeks post-treatment, 409 participants still had undetectable viral load.
At 24 weeks post-treatment, 408 participants (71%) achieved SVR.
Looking back at week 12 results, all but 1 of the patients who were undetectable at week 12 remained so at week 24.
Week 12 response had a positive predictive value of 99.7% for predicting Week 24 SVR.
The researchers concluded that assessment of serum HCV RNA 12 weeks after the end of treatment using a highly sensitive TMA assay "is as relevant as after 24 weeks to predict SVR and make decisions on the management of treated patients, suggesting a new definition for SVR