“…For example, different studies use different modelling approaches, while most use a Markov modelling approach (including health-state transition model [47,61,62], life-long state transition model [63], a discrete-state time dependent semi-Markov model [64]), others use dynamic models (dynamic life-cycle model [35]). The number of states modelled also varies markedly from 3 to 10 states of disease [45,47,51,55,59,64], the variation reflecting in part the focus of the authors (such as cardiac toxicity, recurrence or relapse, HER2 testing and Trastuzumab regime) and the willingness of authors to balance complexity with transparency in models. How models are populated also varies though the relatively small number of trials relating to use of Trastuzumab in early stage breast cancer has served to limit heterogeneity here.…”