Hickam's Dictum: An Analysis of Multiple Diagnoses

Area of Science:

• Medical Diagnosis
• Clinical Reasoning
• Diagnostic Frameworks

Background:

• Hickam's dictum posits patients can have multiple diseases, contrasting with Ockham's razor favoring single diagnoses.
• The phenomenon of multiple diagnoses has lacked formal analysis in clinical practice.

Purpose of the Study:

• To formally analyze the phenomenon of multiple diagnoses.
• To evaluate the relationship between multiple diagnoses and established diagnostic principles like Ockham's razor.
• To develop a framework for understanding and categorizing complex patient cases.

Main Methods:

• Review of 83 published case reports citing Hickam's dictum.
• Analysis of 220 cases from the New England Journal of Medicine.
• Online survey assessing provider intuition on hypothetical multiple-diagnosis scenarios.

Main Results:

• Case reports showed multiple diagnoses categorized as incidentalomas (25.3%), pre-existing diseases (31.3%), causally linked diseases (39.8%), or unrelated diseases (3.6%).
• New England Journal of Medicine cases predominantly featured unifying diagnoses.
• Surveyed providers found causally unrelated, co-occurring diagnoses (Category 4) most surprising (79%).

Conclusions:

• Multiple diagnoses are common, with most being causally linked, incidental, or pre-existing conditions.
• A proposed framework integrating time, probability, and causation reconciles Hickam's dictum and Ockham's razor.
• This framework enhances the practical and pedagogical utility of understanding complex patient cases.