CMS100 Week 3 - Differential Diagnosis

differential diagnosis - definition and purpose

• process of considering multiple possible causes of a patient’s signs and symptoms before arriving at a final diagnosis

• must compare patient info to known illness scripts

• prevents premature diagnosis closure and improves clinical decision-making

value of differential diagnoses

• acknowledges that initial diagnostic impressions can be incorrect

• reduces risk of missing serious or high-risk conditions

• particularly important for beginners, whose first guesses are often inaccurate

premature closure/first-guess error

• tendency to stop considering alternatives after initial hypothesis

• strongly influenced by availability heuristic

  • overreliance on recent in memorable cases

• leads to diagnostic error

possibilism

• attempting to list all possible diagnoses

• results in lists that are excessively long and low-value, as well as confusion and unnecessary testing

principles for constructing differentials

• probability - most likely diagnosis

• prognosis - “must-not-miss” conditions (i.e. chest pain → MUST consider MI)

• pragmatism - conditions with favourable benefit:harm ratio if treated

• these considerations are often applied implicitly within threshold-based reasoning

when to form a differential diagnosis

• after obtaining sufficient info about the chief concern

• avoids prematurely generating broad, non-specific lists

• differential diagnoses should be dynamic and updated as new data emerge

role of problem representation

• effective differential diagnosis depends on a well-constructed problem list and patient illness script

• allows direct comparison between patient features and disease illness scripts

• Differential diagnosis improves __________ by ___________

• Errors arise from _________ and _________ about diagnostic reasoning

• Balanced, focused differentials outperform both overly _______ and excessively _________

• Differential diagnosis improves diagnostic accuracy by challenging initial assumptions

• Errors arise from cognitive biases and misconceptions about diagnostic reasoning

• Balanced, focused differentials outperform both overly narrow and excessively broad lists