Practical delta check limits for tumour markers in different clinical settings

Area of Science:

• Clinical Chemistry
• Laboratory Medicine
• Tumor Marker Analysis

Background:

• Serial monitoring of tumor markers is common, but standardized delta check methods are lacking.
• Delta checks assess the significance of changes in serial laboratory results.
• Few studies have established practical delta check limits for tumor markers.

Purpose of the Study:

• To establish practical delta check limits for five common tumor markers.
• To evaluate these limits across different clinical settings (health check-up, outpatient, inpatient).
• To determine the most appropriate delta check method for serial tumor marker evaluation.

Main Methods:

• Retrospective analysis of tumor marker results (2020-2021) from three university hospitals.
• Data categorized into health check-up, outpatient, and inpatient subgroups.
• Determination and validation of delta percent change (DPC), absolute DPC (absDPC), and reference change value (RCV) limits using development and validation sets.

Main Results:

• Delta check limits (DPC, absDPC) varied significantly across clinical subgroups.
• Proportions requiring further evaluation ranged from 0.2% to 35.3% depending on the method and subgroup.
• In silico simulations demonstrated high negative predictive values (>0.99) for all methods.

Conclusions:

• Delta percent change (DPC) is the most suitable delta-check method for tumor markers.
• Clinical setting-specific delta check limits are recommended for accurate interpretation of serial tumor marker results.