[Systemic autoimmune diseases; diagnostics versus classification].

Area of Science:

• Rheumatology
• Immunology
• Internal Medicine

Background:

• Systemic autoimmune diseases present with diverse clinical features and complex pathogenesis.
• Accurate diagnosis is challenging, often requiring expert evaluation and differential diagnosis.
• Classification criteria, designed for research, are sometimes incorrectly used for clinical diagnosis.

Purpose of the Study:

• To highlight the potential misuse of classification criteria in diagnosing systemic autoimmune diseases.
• To emphasize the importance of clinical diagnosis preceding the application of classification criteria.
• To illustrate the diagnostic challenges arising from overlapping criteria and evolving disease presentations.

Main Methods:

• Review of three distinct patient case histories with systemic autoimmune diseases.
• Analysis of the overlap between established classification criteria for various autoimmune conditions.
• Discussion of the diagnostic process versus the application of classification criteria.

Main Results:

• Two patients met criteria for multiple autoimmune diseases, demonstrating significant overlap.
• A third patient developed a second autoimmune disease (rheumatoid arthritis) after an initial diagnosis (systemic sclerosis), which could have been missed if classification criteria were applied diagnostically.
• Misapplication of classification criteria can obscure accurate diagnosis and disease progression.

Conclusions:

• Classification criteria should not be used as diagnostic tools in clinical practice.
• A thorough clinical diagnosis is essential before utilizing classification criteria for patient cohort selection.
• Understanding the distinction between diagnostic and classification criteria is crucial for managing complex systemic autoimmune diseases.