If the threshold is 20,000 per QALY gained then the INB is calculated as: ( 20,000 QALYs gained) Incremental cost. Indirectness The available evidence is different to the review question being addressed, in terms of PICO (population, intervention, comparison and outcome). Intention-to-treat analysis (ITT) An assessment of the people taking part in a clinical trial, based on the group they were initially (and randomly) allocated to. This is regardless of whether or not they dropped out, fully complied with the treatment or switched to an alternative treatment. Intention-to-treat analyses are often used to assess clinical effectiveness because they mirror actual practice: that is, not everyone complies with treatment and the treatment people receive may be changed according to how they respond to it. Intervention In medical terms this could be a drug treatment, surgical procedure, diagnostic or psychological therapy. Examples of public health interventions could include action to help someone to be physically active or to eat a more healthy diet. Intraoperative The period of time during a surgical procedure. Kappa statistic A statistical measure of inter-rater agreement that takes into account the agreement occurring by chance. Length of stay The total number of days a participant stays in hospital. Licence See Product licence . Life years gained Mean average years of life gained per person as a result of the intervention compared with an alternative intervention. Likelihood ratio The likelihood ratio combines information about the sensitivity and specificity. It tells you how much a positive or negative result changes the likelihood that a patient would have the disease. The likelihood ratio of a positive test result (LR+) is sensitivity divided by (1 minus specificity). Chronic Heart Failure Glossary NICE 2018. All rights reserved. Subject to Notice of rights. 