Methodological challenges of performing meta-analyses to compare the risk of hepatocellular carcinoma between chronic hepatitis B treatments

Despite several recent meta-analyses on the topic, the comparative risk of hepatocellular carcinoma in patients with chronic hepatitis B (CHB) receiving entecavir (ETV) or tenofovir disoproxil fumarate (TDF) remains controversial. The controversy partly results from the arbitrary nature of significance levels leading to contradictory conclusions from very similar datasets. However, the use of observational data, which is prone to both within- and between-study heterogeneity of patient characteristics, also lends additional uncertainty. The asynchronous introduction of ETV and TDF in East Asia, where the majority of these studies have been conducted, further complicates analyses, as does the ensuing difference in follow-up time between ETV and TDF cohorts. Researchers conducting meta-analyses in this area must make many methodological decisions to mitigate bias but are ultimately limited to the methodologies of the included studies. It is therefore important for researchers, as well as the audience of published meta-analyses, to be aware of the quality of observational studies and meta-analyses in terms of patient characteristics, study design and statistical methodologies. In this review, we aim to help clinicians navigate the published meta-analyses on this topic and to provide researchers with recommendations for future work.