J Gastrointestin Liver Dis, March 2021 Vol. 30 No 1: 88-93 1) Gr. T. Popa Univ. of Medicine and Pharmacy, Institute of Gastroenterol. and Hepatol, Iasi; 2) Dept. of Internal Medicine, Fundeni Clinical Institute, Carol Davila Univ. of Medicine and Pharmacy, Bucharest; 3) Dept. of Gastroenterol. and Hepatol, Victor Babes University of Medicine and Pharmacy, Timișoara; 4) Dunarea de Jos University of Galati, Sf Cuv Parascheva, Clinical Hospital of Infectious Disease Galati; 5) Digestive Diseases and Liver Transplantation Center, Fundeni Clinical Institute, Bucharest, Carol Davila Univ. of Medicine and Pharmacy, Bucharest; 6) Iuliu Hatieganu Univ. of Medicine and Pharmacy, Cluj-Napoca; 7) Prof. Dr. Octavian Fodor Regional Institute of Gastroenterol. and Hepatol, Cluj-Napoca; 8) Babes- Bolyai Univ, Dept. for Clinical Psychology and Psychotherapy, International Institute for Advanced Studies in Psychotherapy and Applied Mental Health, Cluj- Napoca; 9) Prof. Dr. Matei Balș National Institute of Infectious Diseases, Carol Davila University of Medicine and Pharmacy, Bucharest, Romania Address for correspondence: Adrian Streinu-Cercel, Prof. Dr. Matei Balș National Institute of Infectious Diseases, Carol Davila Univ. of Medicine and Pharmacy, Bucharest, Romania astreinucercel@yahoo.com Received: 05.01.2021 Accepted: 12.02.2021 Efectiveness of 8- and 12-Week Treatment with Ombitasvir/ Paritaprevir/Ritonavir and Dasabuvir in Treatment-Naïve HCV Patients in a Real-Life Setting in Romania: the AMETHYST Study Anca Trifan 1 , Carol Stanciu 1 , Laura Iliescu 2 , Ioan Sporea 3 , Liliana Baroiu 4 , Mircea Diculescu 5 , Mihaela-Catalina Luca 4 , Egidia Mifode 4 , Cristina Cijeveschi 1 , Catalina Mihai 1 , Zeno-Adrian Sparchez 6,7 , Cristina Pojoga 7,8 , Adrian Streinu- Cercel 9 , Liliana Gheorghe 5 INTRODUCTION The interferon-free combination of ombitasvir/ paritaprevir/ritonavir plus dasabuvir (OPrD) for the treatment of chronic infection with hepatitis C virus (HCV) has demonstrated its efcacy in randomized controlled clinical trials, including in treatment- naive patients without cirrhosis [1-5]. Although efficacy can be defned as the capacity of a treatment to produce the desired effect in an ideal, controlled environment (eg, a randomized trial), effectiveness is defined ORIGINAL PAPER DOI: http://dx.doi.org/10.15403/jgld-3373 ABSTRACT Background & Aims: Te 12-week regimen of ombitasvir/paritaprevir/ritonavir and dasabuvir (OPrD) has shown high efcacy and tolerability in clinical trials for the treatment of chronic hepatitis C virus (HCV). Te shorter 8-week regimen has been recently incorporated into clinical guidelines and on-label indications, but real-world evidence on its use is limited. Given this knowledge gap, the AMETHYST study aimed to evaluate the efectiveness of the 8- and 12-week regimens of OPrD in treatment-naive patients with HCV with mild to moderate liver fbrosis in Romanian clinical practice. Methods: Tis was a secondary data collection study analyzing data from a 1-year Patient Support Program in HCV in Romania. Patients received OPrD treatment for 8 or 12 weeks. Te efectiveness endpoint was sustained virologic response 12 weeks post-treatment (SVR12). Results: A total of 1,835 treatment-naive patients with HCV with mild or moderate fbrosis were included in the study. Of these, 426 and 1,375 completed the 8-week and 12-week regimens, respectively. SVR12 was 98.1% in the 8-week treatment group and 98.7% in the 12-week treatment group. Conclusion: Te study provides real-world evidence that 8-week and 12-week treatment regimens of OPrD are highly efective in treatment-naive patients with HCV with mild to moderate liver fbrosis. Key words: hepatitis C virus − ombitasvir − paritaprevir − ritonavir − dasabuvir − real-world − sustained virologic response − 8-week and 12-week treatment. Abbreviations: CP: core population; CPSFU: core population with sufcient follow-up data; HCV: hepatitis C virus; LLoQ: lower limit of quantifcation; OPrD: ombitasvir/paritaprevir/ritonavir plus dasabuvir; PSP: Patient Support Program; SVR12: sustained virologic response 12 weeks afer the end of treatment; TE: transient elastography. as the extent to which a drug achieves its intended efect in a real-world context [6, 7]. Effectiveness trials usually include few or no exclusion criteria and a broader patient population from standard clinical practice, a group that is ofen underrepresented in clinical trials [7]. When measured in interventional settings versus routine clinical practice, drug efectiveness estimates difer. Tese diferences are explained by the well-recognized lack of external validity of the clinical randomized trials on one hand and the numerous possible interactions of the real-life factors with the biological efect of the drug on the other [8]. Te initial label recommendation of the OPrD combination was supported by the results of randomized clinical studies that included a 12-week treatment regimen [1, 3-5]. Te current label states that a shortened regimen of 8 weeks is a therapeutic option that can be considered in previously untreated patients with mild to moderate liver fbrosis, based on the GARNET study results [9]. Te 8-week regimen seems to be a more