Evidence-based Medicine Toolkit

68 Evidence-based Medicine Toolkit7 Did the study include all the relevant outcomes for eachintervention?Usually, economic evaluations will represent outcomes using naturalunits (such as number of heart attacks prevented, life-yearsgained or number of visits to the GP). The disadvantage of suchmeasures is that they don’t usually encompass all of the aspects ofthe intervention.As noted above, costs for each outcome should be provided sothat a cost–benefit analysis can be carried out. The advantage ofnatural units is that they better reflect clinical priorities.Sometimes, a cost–utility study will be conducted, in which thepossible outcomes are rated by patients using a sliding scale torepresent quality of life. This might range from zero (death) to one(perfect health). This helps us to factor in the patients’ views intolarge-scale assessment of cost-effectiveness. Such studies, it’s possibleto measure the ‘amount of health’ gained by an interventionrather than just the specific number of events prevented.