The hepatitis C virus (HCV) remains a major global health burden and a leading cause of liver malignancies. Patients with serious mental illness (SMI) who live with HCV are disproportionately affected and frequently underserved by existing healthcare systems. A prior meta-analysis reported an HCV prevalence of 8% in this population, which exceeds general-population estimates. Given the period of the COVID-19 pandemic and ongoing changes in healthcare delivery and testing, an updated systematic review and meta-analysis is planned to incorporate studies published since the earlier review and to assess any shifts in prevalence, risk factors and barriers to care.
This protocol mirrors the methodology of the original review to ensure continuity and comparability of findings. The update will apply a systematic search across multiple bibliographic databases to identify relevant observational studies published between 2 July 2020 and 22 June 2026. Study designs eligible for inclusion are prospective observational studies and retrospective cross-sectional studies that report laboratory-confirmed HCV status among adults with a verified diagnosis of SMI.
A dual-reviewer approach will be used throughout screening and selection to reduce bias. Two reviewers will independently evaluate titles, abstracts and full texts; a third senior investigator will adjudicate any disagreements. The review will apply a validated quality-assessment instrument and a brief customised global rating to summarise methodological rigour.
Eligible studies must meet the following conditions as defined in the protocol:
If details necessary to confirm eligibility are missing from a study report, this protocol specifies that the study will be evaluated according to the information available; the source did not report additional procedures for handling missing eligibility data.
A comprehensive search strategy will be executed across the following databases: PubMed, Google Scholar, Scopus, CINAHL (Cumulative Index to Nursing and Allied Health Literature), Embase and Web of Science. The search is intended to capture peer-reviewed literature published within the prespecified timeframe to update the evidence base after the original review.
The protocol indicates replication of the earlier review's methods for search construction and study selection; specific search strings, filters or language restrictions were not reported in the source text.
Titles, abstracts and full-text manuscripts retrieved by the search will be screened independently by two reviewers. The dual-reviewer process aims to minimise selection bias and ensure consistent application of inclusion criteria. Discrepancies between reviewers will be resolved by consultation with a third senior investigator who will adjudicate disagreements.
The source did not provide a detailed data-extraction form or a full list of variables to be extracted; it states only that the dual-reviewer protocol will be used for evaluation of retrieved records.
Methodological rigour of included studies will be appraised using the Joanna Briggs Institute (JBI) Critical Appraisal Checklist for Prevalence Studies. This validated tool is designed to assess bias and reporting quality in prevalence research and will support transparent, standardised assessment across studies. The JBI appraisal will be supplemented by a customised three-point global assessment to provide a concise summary judgement of overall study quality.
The protocol does not report how JBI or global-assessment results will influence inclusion or sensitivity analyses; those details were not provided in the source text.
For meta-analytical synthesis the protocol specifies use of a Generalised Linear Mixed Model (GLMM) with a logit transformation. This modelling approach is chosen to accommodate expected between-study heterogeneity and to handle extreme prevalence proportions reliably.
Heterogeneity across studies will be quantified using the I2 statistic to report the degree of inconsistency. The source text does not report planned subgroup or meta-regression analyses, nor does it specify software or thresholds for interpreting I2; those details were not reported.
Formal ethical clearance is not required for this review because it synthesises data from already published studies and does not involve collection of primary data. The protocol states that the study will rely entirely on secondary data from published articles. Plans for dissemination (for example, target journals, conferences or stakeholder engagement) were not detailed in the provided source text.
This systematic review and meta-analysis has been registered on PROSPERO under the registration number CRD420261331799. The registration confirms intent to follow a pre-specified protocol for the update and provides a public record of methods and aims.
Note: Where the source did not report specific procedural details (for example exact search strings, data-extraction variables, planned subgroup analyses or software choices), those specifics were not added and are noted as not reported in the source.