A patient assessment comprises an initial scan for sub epidermal moisture 644 (SEM) of a body location selected for monitoring. The patient is assigned to a risk category, based partially on the initial SEM scan of the body location. A delta value is calculated for a previous SEM scan. If the delta value for a body location is greater than a first threshold, a SEM scan is performed on that body location after a first time interval. If the delta value is exceeds a second threshold, a SEM scan is performed after a second time interval which is shorter than the first time interval. In this way, SEM measurements may be limited to when they are needed.
