Fig. 1.

Diagram of combination therapy. Dual therapy is defined as the concurrent use of nucleos(t)ide analogues (NUCs) and interferon (IFN) during the entire treatment course. Add-on therapy is defined as a sequential combination of NUCs and pegylated IFN (PegIFN), whereby the combination is employed for more than 12 weeks, with two types of combinations: NUC-based therapy with add-on PegIFN and PegIFN-based therapy with add-on NUCs. Switch therapy is defined as a long-term NUC or PegIFN therapy with a subsequent switch to PegIFN or NUCs, with or without a short period (≤12 weeks) of overlap of both agents.