1. A method of determining a treatment program for a subject, the method being performed by a processing system, the method comprising: a) obtaining subject data, the subject data representing the subject's a condition of the subject; b) constructing a mathematical model comprising one or more differential equations representing a progression of the condition, the progression being a development of the condition over time; c) analyzing, using the processing system, the subject data and the model of the condition to determine system values representing the condition; d) determining, using the processing system, one or more solution trajectories, the solution trajectories being solutions to the differential equations and representing potential routes of progression of the condition within the subject, the solution trajectories being determined in accordance with the model and the determined system values; and e) determining a treatment program in accordance with the determined solution trajectories.