A clinical evaluation of various delta check methods

Area of Science:

• Clinical Chemistry
• Laboratory Medicine
• Medical Diagnostics

Background:

• Delta checks are used to detect errors in laboratory testing by comparing sequential results.
• Evaluating the performance of different delta check methods is crucial for improving laboratory quality assurance.

Purpose of the Study:

• To assess the effectiveness of three distinct delta check techniques in identifying potential errors in continuous-flow laboratory test results.
• To quantify the rate of true positives versus false positives generated by these delta check methods.

Main Methods:

• Analysis of 707 unselected pairs of continuous-flow test results.
• Application of three different delta check methods, including specific analytes like urea nitrogen/creatinine ratio and anion gap.
• Investigation of delta check failures through subsequent tests, specimen retesting, and patient chart review to classify as true or false positives.

Main Results:

• The percentage of true positive delta check failures ranged from 5% to 29% across the evaluated methods.
• All three methods exhibited variability, with certain test types yielding higher percentages of true positives than others.
• A significant number of false positives were observed, often due to physiological changes from disease processes or therapeutic interventions.

Conclusions:

• Delta check methods are valuable for detecting laboratory errors that might otherwise be missed.
• The clinical utility of delta checks is tempered by a substantial rate of false positives, necessitating thorough investigation.
• Understanding the impact of patient-specific factors like disease and therapy is essential when interpreting delta check results.