21 February 2019 - When designing a comparative outcomes or a cost-effectiveness analysis, the time horizon defining the duration of time for outcomes assessment must be carefully considered. 

The time horizon must be long enough to capture the intended and unintended benefits and harms of the intervention(s). In some instances, the time horizon should extend beyond the duration of a clinical trial when a specific end point is measured, whereas in other instances modelling outcomes over a longer period is unnecessary. 

Using a longer time horizon than is necessary may add unnecessary cost and complexity to the cost-effectiveness analysis model.

Read JAMA Guide to Statistics and Methods