Fig. 2

Conceptual model of the dynamic population simulation. Each solid circular dot on the left margin represents an AS patient at the time point when he or she enters the simulation. The patients are differentiated into groups, including the prevalent population on 1 January 2014 and incident cohorts in years 2014–2034, whose sizes are calculated based on the sizes of the general population and prevalence and incident rate. Each solid horizontal line represents the temporal movement of each patient, which ends when the patient dies (marked with a solid diamond) or reaches January 1, 2034 (marked with an open circle on the vertical bar on the right margin). The open circles represent the patients in the prevalent population at a time point of interest who are included in the summary statistics of disease measures, costs and health utilities