Dictionary of Evidence-based Medicine.pdf

84 Dictionary of Evidence-based Medicine
In incremental cost-effectiveness analysis, estimated incremental costs
are divided by the estimated incremental number of effectiveness units to
give an incremental cost-effectiveness ratio (CER). In a multitreatment
comparison, the incremental CER should be calculated relative to the next
most effective mutually exclusive alternative (see Dominance) (Weinstein
MC, Zeckhauser R (1973) Clinical ratios and efficient allocation. Journal of
Public Economics. 2:147-57).
IND
An IND is an investigational new drug in relation to drug licence applications
to the US Food and Drug Administration.
Index date
In a case-control study, subjects are recruited to identify association
between an adverse event (e.g. pulmonary hypertension) and exposure to
a putative risk factor (e.g. anorectic agents). Cases (e.g. patients with
pulmonary hypertension) identified and matched controls are then interviewed
to assess exposure to the risk factor (e.g. anorectic drugs) and
presence of confounding factors (e.g. high body mass index, drug abuse or
smoking). The index date is the date from which the cases and controls
recruited are asked to recall their exposure history to the various risk
factors (e.g. date from which they first perceived a symptom such as dyspnoea
in assessing pulmonary hypertension).
Indifference curve
We are often put in a position of having to choose relative amounts of
different goods which we would like to have at least some of (e.g. food
and medicine or extent and quality of life; my students like to consider
the trade-off between beer and food). An indifference curve is a graphical
illustration of a person's preference between two or more goods. Figure 12
is an example of an indifference curve involving two goods. The subject
concerned is as happy with point PI (15 units of A and 4 units of B) as with
point P2 (6 units of A and 10 units of B).
Information bias (see under Bias)
Informed choice (see under Subjective preference)