The process of formulating economic questions can also help to clarify the set of important measures of resource use, costs or cost-effectiveness (or a combination of these) to be included as target outcomes in a review. These outcomes should be included alongside other target outcomes in the ‘Types of outcome measures’ part of the ‘Criteria for considering studies for this review’ section of a review. Wherever possible, it is useful to break down measures of resource use and costs to the level of specific items or categories (e.g. length of hospital stay in days, duration of operation in minutes, number of outpatient attendances, bleeds from secondary prophylaxis at six-month follow-up, number of days off work, direct medical resource use, direct medical costs, indirect medical resource use or costs, patient out-of-pocket expenses) and to avoid the use of general descriptive terms for outcomes (e.g. ‘costs’, ‘resource utilization’, ‘health economics’). Measures of cost-effectiveness that may be included as target outcome measures in a review include incremental cost-effectiveness ratios (ICERs), incremental cost-per QALY and cost-benefit ratios (see also Section 15.1.2).