INTRODUCTION
Core Knowledge for
Medical Decision-making
Jeffrey R. Avner, MD
Key Points

Rational medical decision-making requires knowledge of cognition, inher-
ent biases, and disease prevalence and risk, and an understanding of pretest
and posttest probabilities.

Medical decision-making is influenced by clinical (ie, history and physical
examination) and nonclinical (eg, patient, clinician, practice) factors.

Clinicians need to learn and recognize the shortcomings and biases that
may be part of their own decision-making.

The hierarchy of study validity can provide a means of interpreting the level
of evidence a study provides.

Evidence-based medicine in the form of systematic reviews is a useful way
of obtaining the best available data on a specific research question.
Overview
Medical decision-making is the cornerstone of diagnostic medicine. It is a
complicated cognitive process by which a clinician sorts through a variety of
clinical information to arrive at a likely diagnosis among many possibilities.
This diagnostic impression then forms the basis of patient management with
the ultimate goal of improved health.
However, any medical decision-making contains some inherent element
of uncertainty. Furthermore, the ability of a clinician to obtain all necessary
information and ensure its accuracy is time-consuming and often impractical
in most clinical settings. Many turn to heuristics, an intuitive understanding of
probabilities, to drive cognition and arrive at an “educated guess,” one that is
based on the recognition of specific patterns in clinical findings associated with
a particular diagnosis and gleaned from years of experience. With this knowl-
edge, the clinician can quickly sort through a limited set of historical and
physical examination findings to support the decision. However, this type of
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