Direct-acting antivirals for chronic hepatitis C infection: a protocol for a systematic review of observational studies

BackgroundChronic hepatitis C virus infection presents a substantial global health burden, frequently resulting in severe liver conditions. Hepatitis C virus (HCV) therapy requires complex decision-making. Direct-acting antivirals (DAAs) offer a potential solution by targeting viral proteins to inhibit replication. Understanding DAAs real-world effectiveness and how they impact long-term outcomes beyond clinical trials is essential. We aim to comprehensively evaluate the benefits and harms of DAAs in individuals with chronic HCV infection, reported in observational studies. MethodsWe will consider for inclusion prospective and retrospective observational studies with quasirandomised, cohort, case-control, controlled before-and-after, and cross-sectional designs. Our experimental interventions will be any class of DAAs available on the market or in development. DAAs could have been administered alone, in combination, or with other medical co-interventions. Our control interventions will be untreated chronic HCV conditions, with or without placebo. Participants will be adults, regardless of demographics, treatment history, or healthcare setting. Our primary outcomes will be participants experiencing hepatitis C-related morbidity or all-cause mortality, serious adverse events, and health-related quality of life. Secondary outcomes will include all-cause mortality, cirrhosis, variceal bleeding, hepato-renal syndrome, hepatocellular carcinoma, hepatic encephalopathy, non-serious adverse events, liver transplantation, lack of sustained virological response, histological improvement, and decreases in alanine aminotransferase and aspartate aminotransferase levels. We will apply search strategies to search MEDLINE, Embase, Web of Science, grey literature, and trial registers. We will use Covidence(R) to screen the result, including citations. Individual double-data extraction will include study details and outcomes, with independent review authors resolving discrepancies. We will assess bias using the ROBINS-I tool. Meta-analyses will employ random-effects models for both dichotomous and continuous outcomes, assessing heterogeneity. Subgroup and sensitivity analyses will explore effect modifications and address missing data. Trial Sequential Analysis will control type I and type II errors. We will evaluate publication bias using funnel plots and Eggers regression test and assess certainty of evidence using GRADE. DiscussionThe findings will inform clinical decisions and benefit those affected by HCV, healthcare professionals, and policymakers. Systematic review registrationPROSPERO: CRD42023494844