All troponins are not created equal

Area of Science:

• Cardiology
• Clinical Chemistry
• Biomarker Analysis

Background:

• Troponin assays are crucial for diagnosing acute coronary syndromes (ACS).
• Clinical decisions rely on categorizing troponin results as positive or negative.
• Variability between troponin assays may impact patient diagnosis and management.

Purpose of the Study:

• To evaluate the categorical agreement between four different troponin assays.
• To assess the impact of assay variability on the classification of troponin results.

Main Methods:

• Analysis of 60 blood samples using three troponin I assays (Centaur, Architect, i-STAT) and one troponin T assay (Roche Elecys).
• Determination of upper reference limits based on a 10% coefficient of variation.
• Assessment of continuous agreement using Pearson's correlation and categorical agreement using Cohen's kappa.

Main Results:

• Continuous agreement between assays was generally good (Pearson's r = 0.871-0.995).
• Categorical agreement varied from poor (kappa = 0.37-0.48) to good (kappa = 0.68).
• The percentage of positive results ranged from 37% to 72%, a nearly twofold variation.

Conclusions:

• Significant variations exist in the proportion of positive results among different troponin assays.
• This variability may lead to missed diagnoses or false positives, affecting ACS management.
• Clinical judgment and context are essential when interpreting troponin results, rather than relying solely on local assay normal ranges.