ISBN: 978-1-4731-3093-7 Term Definition Health economics Study or analysis of the cost of using and distributing healthcare resources. Health-related quality of life (HRQoL) A measure of the effects of an illness to see how it affects someone s day- to-day life. Heterogeneity or Lack of homogeneity The term is used in meta-analyses and systematic reviews to describe when the results of a test or treatment (or estimates of its effect) differ significantly in different studies. Such differences may occur as a result of differences in the populations studied, the outcome measures used or because of different definitions of the variables involved. It is the opposite of homogeneity. Imprecision Results are imprecise when studies include relatively few patients and few events and thus have wide confidence intervals around the estimate of effect. Inclusion criteria (literature review) Explicit criteria used to decide which studies should be considered as potential sources of evidence. Incremental analysis The analysis of additional costs and additional clinical outcomes with different interventions. Incremental cost The extra cost linked to using one test or treatment rather than another. Or the additional cost of doing a test or providing a treatment more frequently. Incremental cost- effectiveness ratio (ICER) The difference in the mean costs in the population of interest divided by the differences in the mean outcomes in the population of interest for one treatment compared with another. Incremental net benefit (INB) The value (usually in monetary terms) of an intervention net of its cost compared with a comparator intervention. The INB can be calculated for a given cost-effectiveness (willingness to pay) threshold. If the threshold is 20,000 per QALY gained then the INB is calculated as: ( 20,000 QALYs gained) Incremental cost. 