Approaches to economic evaluation in telemedicine.

External validity or generalizability is a major challenge in the economic evaluation of telemedicine. There are two possible ways of increasing generalizability: the first is to use a pragmatic trial design so it better reflects normal patient caseload and everyday practice. The second is to use existing data from the literature and decision modelling to estimate the expected costs and outcomes of different alternatives. The first will increase generalizability to other patients than those in the trial and the second will increase generalizability from place to place. The objective and role of the evaluation will decide the most appropriate evaluation approach. Pragmatic trials should be used in studies where the objective is to provide measurements of costs and outcomes for a specific group of patients in a particular setting. This approach is highly relevant in telemedicine evaluations where the objective is to support local investments strategies and reimbursement systems. Decision modelling provides an overall structure for a decision problem and a formal analysis of the implications of different decisions. Modelling can simulate a trial or mimic a current system or a system that decision makers would like to use. Modelling is a useful approach when decisions need to be made about whether to invest in telemedicine within a broader context.