Fig. 3. Example of how more frequent testing of serum HCV RNA, particularly during the first 3 to 6 months of treatment, can improve recognition of EVR, VR, and the null response. (A) This patient was having a stepwise decline in HCV RNA at 1 and 2 months, but the value at 3 months was slightly higher and fell just short of a 2-log decline from baseline (arrow). By measuring serum HCV RNA monthly during the first 3 months of treatment, it was recognized that the patient already had a 2-log decline in serum HCV RNA at month 2 and that the elevation at 3 months could have represented assay variation. Treatment was continued, and the patient achieved VR by month 6. If only one HCV RNA value had been obtained at month 3 (arrow), treatment would have been discontinued, and the patient would have been labeled as an NR. (B) This patient had become HCV RNA undetectable by treatment month 2 but was HCV RNA positive at treatment month 6 (arrow). If HCV RNA had not been measured at monthly intervals, the patient might have been mischaracterized as an NR at month 6 and treatment discontinued. Because HCV RNA had been measured at monthly intervals, VR had been recognized. The positive HCV RNA value at month 6 was a discordant value, and treatment was continued.
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