Methodological challenges in appraising evidence on diagnostic testing for WHO guidelines on hepatitis B and hepatitis C virus infection

Linking persons with hepatitis B (HBV) and hepatitis C (HCV) infection with appropriate prevention and treatment requires that they first be diagnosed. The World Health Organization (WHO) has developed its first guidelines on testing for chronic HBV and HCV infection, using a framework based on methods from the Grading of Recommendations, Assessment, Development, and Evaluation (GRADE) Working Group for the formulation of recommendations, including determining the strength of recommendations and quality of evidence. Recommendations were formulated based on the overall quality of the evidence, in addition to other considerations, including the balance between benefits and harms, values and preferences, feasibility and resource implications. This article summarizes methodological challenges and additional considerations encountered in applying these procedures to diagnostic testing for viral hepatitis, and strategies to address these. Direct evidence on the effects of tests and test strategies on clinical outcomes was not available. Given the availability of effective treatments for HBV and HCV that are generally acceptable to patients, the Guidelines Development Group (GDG) considered diagnostic accuracy a reasonable surrogate for clinical outcomes. In order to increase the number of patients identified with chronic HBV and HCV infection who could benefit from treatments, the GDG determined that tests and testing strategies associated with slightly lower diagnostic accuracy could be recommended when associated with lower costs; increased testing access, uptake, and linkage to care; greater feasibility; or if preferred by patients.