scope:

This guideline provides recommendations for evaluating the changes between consecutive test results for the same patient in the same matrix. These evaluations are called delta checks. This guideline reviews the selection and use of delta checks and provides basic information for laboratories that intend to use delta checks. This document considers several uses, including detection of misidentified samples, contaminated or otherwise compromised samples, and clinically significant changes in patients' test results. This guideline reviews approaches to setting limits for expected differences in consecutive test results, selection of appropriate measurands for use in delta checks, and the types of comparisons that could be used; an approach to evaluating samples that have delta check alerts; and suggested approaches to evaluate the effectiveness of delta checks once they have been implemented. It also provides guidance for defining appropriate follow-up steps for delta check alerts and for the evaluation of the performance of a laboratory's delta check program.

The intended users of this guideline are medical laboratory management and personnel. This information may also be of interest to hospital or laboratory informatics staff, and software and medical device vendors who need to understand the laboratory's goals when implementing an automated delta check program.

This guideline does not directly discuss informatics aspects (computer programming) for establishing delta checks, or methods for determining the precision of the test methods used.