Cochrane definition: Decision Aids are adjunct to counseling to prepare patients for decision making. According to the Cohcrane systematic review definiton, a DA provides (at a mininmum) information on the alternatives, benefits, and risks appropriate for patients' clinical condition.

Additional elements may or may not include: information on the disease of condition; tailoring the probabilities of outcomes to the patient's clinical risk; exercises for clarifying personal values; information on others' opinions or recommendations; and guidance or coaching in the steps of decision making and communicating with health care providers.

Excluded from the definiton are: a) general educational programs or information materials not geared to a specific decision; b) education designed to promote compliance with a recommneded option rather than a choice based on personal values; and c) passive informed consent materials where patients are advised to have a procedure and are asked to sign a consent form. (BMJ, 1999;319:731-735).

The conscientious, explicit, and judicious use of current best evidence in making decisions about the care of individual patients” (Sackett et al., 1996)

A statistical concept = (probability of gain) * (utility of gain) + (probability of loss) * (utility of loss) .

Normative theory of choice under uncertainty.

A statistical concept. It expresses the overall value one would obtain with repeated lotteries, given a particular probability (p) of gain, and probability (1-p) of loss. The expected value of any lottery =

(probability of gain)*(value of gain) + (probability of loss)*(value of loss)

Deviation from rational decision making behavior.

Examples:

• Hindsight bias
• Framing effects
• Sequencing effects
• Anchoring effects
• Recency effects
• Representative biases, such as ignoring the prior probability of a disease

Normative theory of decisions with multiple objectives.

The appraisal by an individual regarding the relative desirability of entities, such as health states, treatment, outcomes of treatment / care, or other aspects of health care.

p(event) = number of times a event occurs / total number of possible events.

Refers to the concept of involving patients with their health care providers in making treatment decisions that are informed by the best available evidence about treatment options, potential benefits, and harms, and that consider patient preferences.

A quantitive, subjective measure of strength of preference. It indicates under conditions of risk, the position of a set of entities (say Y1, Y2, Y3) relative to the most preferred (x) and least preferred entity (Z) Can be assessed with several methods / metrics.

Generally, the least preferred entity is given a utility score of 0, the most preferred is given a score of 1. Thus, each of the Y entities has a utility score between 0-1.

When utility scores are plotted, the resulting utility functions is are non-linear, because theu are affected by risk attitudes.

In utility theory, the concept of value measures the position of an entitiy on an underlying objective scale, like money, survival time, length of stay. A value function is linear in form.