Fig. 5

Relative risk and sample size per group varying follow-up time. Plotted curves represent the relative risk (Panel a) and the corresponding sample size needed per group (Panel b) while varying the follow-up time using for all other model parameters the baseline values (Table 1, Generic sample size calculation): immediate progression (dotted line); constant progression (dashed-dotted line); and progression at the end (dashed line). The red circles indicate the follow-up time which minimises the sample size needed per group for the constant progression and progression at the end