Chen‐Hua LiuYu‐Ping ChangJi‐Yuh LeeChi‐Yi ChenWei‐Yu KaoChih‐Lin LinSheng‐Shun YangYu‐Lueng ShihCheng‐Yuan PengFu‐Jen LeeMing‐Chang TsaiShang‐Chin HuangTung‐Hung SuTai‐Chung TsengChun‐Jen LiuPei‐Jer ChenJia‐Horng Kao2026-02-042026-02-042024-0510.1002/jmv.29675https://scholars.csmu.edu.tw/handle/123456789/4980<jats:title>Abstract</jats:title> <jats:p> Early confirmation of sustained virologic response (SVR) or viral relapse after direct‐acting antivirals (DAAs) for hepatitis C virus (HCV) infection is essential based on public health perspectives, particularly for patients with high risk of nonadherence to posttreatment follow‐ups. A total of 1011 patients who achieved end‐of‐treatment virologic response, including 526 receiving fixed‐dose pangenotypic DAAs, and 485 receiving other types of DAAs, who had available off‐treatment weeks 4 and 12 serum HCV RNA data to confirm SVR at off‐treatment week 12 (SVR <jats:sub>12</jats:sub> ) or viral relapse were included. The positive predictive value (PPV) and negative predictive value (NPV) of SVR <jats:sub>4</jats:sub> to predict patients with SVR <jats:sub>12</jats:sub> or viral relapse were reported. Furthermore, we analyzed the proportion of concordance between SVR <jats:sub>12</jats:sub> and SVR <jats:sub>24</jats:sub> in 943 patients with available SVR <jats:sub>24</jats:sub> data. The PPV and NPV of SVR <jats:sub>4</jats:sub> to predict SVR <jats:sub>12</jats:sub> were 98.5% (95% confidence interval [CI]: 98.0–98.9) and 100% (95% CI: 66.4–100) in the entire population. The PPV of SVR <jats:sub>4</jats:sub> to predict SVR <jats:sub>12</jats:sub> in patients receiving fixed‐dose pangenotypic DAAs was higher than those receiving other types of DAAs (99.8% [95% CI: 98.9–100] vs. 97.1% [95% CI: 96.2–97.8], <jats:italic>p</jats:italic>  &lt; 0.001). The NPVs of SVR <jats:sub>4</jats:sub> to predict viral relapse were 100%, regardless of the type of DAAs. Moreover, the concordance between SVR <jats:sub>12</jats:sub> and SVR <jats:sub>24</jats:sub> was 100%. In conclusion, an off‐treatment week 4 serum HCV RNA testing is sufficient to provide an excellent prediction power of SVR or viral relapse at off‐treatment week 12 among patients with HCV who are treated with fixed‐dose pangenotypic DAAs. </jats:p>[SDGs]SDG3Four weeks of off‐treatment follow‐up is sufficient to determine virologic responses at off‐treatment week 12 in patients with hepatitis C virus infection receiving fixed‐dose pangenotypic direct‐acting antiviralsjournal-article