AGACNP Clinical Reasoning and Screening Study Cards

Vocabulary flashcards focusing on clinical reasoning, diagnostic error cognitive biases, statistical formulas, and clinical screening guidelines based on AGACNP study material.

Clinical reasoning

The process of constructing a differential diagnosis, choosing diagnostic tests, and interpreting the results.

System 1 reasoning

Rapid, intuitive pattern recognition that matches a presentation to a stored illness script.

System 2 reasoning

Slower, explicit, analytic reasoning; used more in complicated or unfamiliar cases.

Availability bias

Considering an easily remembered diagnosis more likely regardless of its actual prevalence.

Base-rate neglect

Pursuing rare diagnoses ('zebras') while underweighting prevalence.

Representativeness bias

Ignoring atypical features that are inconsistent with the favored diagnosis.

Confirmation bias

Seeking data that confirm the initial hypothesis rather than trying to refute it.

Premature closure

Stopping the diagnostic process too soon.

Pivotal point

One of a pair of opposing descriptors that helps organize and narrow a differential (e.g., unilateral vs bilateral edema).

Possibilistic approach

Treats all causes as equally likely and tests for all simultaneously; described as not clinically useful.

Probabilistic approach

Prioritizes the diagnoses with the highest pretest probability.

Prognostic approach

Prioritizes the most serious diagnoses.

Pragmatic approach

Prioritizes diagnoses most responsive to treatment.

Leading hypothesis

The most likely diagnosis based on prevalence, demographics, risk factors, symptoms, and signs.

Active alternatives

Must-not-miss diagnoses, common diagnoses, or diagnoses reasonably likely from the patient's features.

Test threshold

The probability below which disease is so unlikely that it can be excluded without further testing.

Treatment threshold

The probability above which disease is so likely that treatment can begin without further testing.

Sensitivity

The proportion of patients WITH disease who test positive; calculated as $\frac{\text{TP}}{\text{TP} + \text{FN}}$.

Specificity

The proportion of patients WITHOUT disease who test negative; calculated as $\frac{\text{TN}}{\text{TN} + \text{FP}}$.

False-negative rate formula

$$1 - \text{sensitivity} = \frac{\text{FN}}{\text{TP} + \text{FN}}$$

False-positive rate formula

$$1 - \text{specificity} = \frac{\text{FP}}{\text{TN} + \text{FP}}$$

SnNout

A mnemonic stating that a highly SeNsitive test, when Negative, helps rule OUT disease.

SpPin

A mnemonic stating that a highly SPecific test, when Positive, helps rule IN disease.

Positive Likelihood Ratio (LR+)

Calculated as $\frac{\text{Sensitivity}}{1 - \text{specificity}}$. An $\text{LR+} > 10$ causes a large increase in disease probability.

Negative Likelihood Ratio (LR-)

Calculated as $\frac{1 - \text{sensitivity}}{\text{Specificity}}$. An $\text{LR-} < 0.1$ causes a large decrease in disease probability.

Screening

Identifying an unrecognized disease or risk factor in a seemingly well person.

Lead-time bias

Earlier diagnosis makes survival from the time of diagnosis appear longer even if the time of death is unchanged.

Length-time bias

Screening preferentially detects slower-growing disease, creating a screened group with an apparently better prognosis.

USPSTF Grade A

Recommend the service; high certainty of substantial net benefit.

USPSTF Grade B

Recommend the service; high certainty of moderate benefit or moderate certainty of moderate-to-substantial benefit.

USPSTF Grade C

Selectively offer based on professional judgment and patient preferences; net benefit is small.

USPSTF Grade D

Recommend against; no net benefit or harms outweigh benefits.

USPSTF I statement

Evidence is insufficient to determine the balance of benefits and harms.

Abdominal Aortic Aneurysm (AAA)

Defined in the text as an infrarenal aortic diameter $> 3.0\,\text{cm}$.

Friedewald-style LDL equation

$\text{LDL} = \text{total cholesterol} - \left(\frac{\text{triglycerides}}{5} + \text{HDL}\right)$; valid when fasting triglycerides are $< 400\,\text{mg/dL}$.

FRAX

A tool that estimates the $10\text{-year}$ probability of hip fracture or major osteoporotic fracture.

Osteoporosis Self-Assessment Tool (OST) formula

$$[\text{weight\,(kg)} - \text{age\,(years)}] \times 0.2$$

Osteoporosis T-score definition

$$\text{T-score} \le -2.5$$

Osteopenia T-score definition

$\text{T-score}$ between $-1.0$ and $-2.5$.

Overdiagnosis

In prostate screening, the detection of indolent cancers that would never have become symptomatic or affected health.

Number Needed to Treat (NNT)

Calculated as $\text{NNT} = \frac{1}{\text{ARR}}$, where $\text{ARR}$ is absolute risk reduction.