Delta check, also known as Delta Delta check or Delta difference check, is a quality control practice used in medical laboratories to detect significant changes in patient test results over time. It involves comparing the current test result for a specific analyte with the previous results for the same patient. The goal of the delta check is to identify unexpected or large variations in results that might indicate errors, physiological changes, or other factors that need further investigation.
Delta check is applied by setting predefined criteria for acceptable changes in test results. If the difference between the current result and the previous result exceeds these criteria, it triggers an alert for laboratory personnel to review the results and take appropriate actions if necessary.
Here’s how the delta check is applied:
- Collecting Data: The laboratory collects and stores historical test results for each patient. This data includes the patient’s previous test results for the same analyte.
- Setting Criteria: The laboratory establishes acceptable delta limits based on factors such as the analyte being measured, the patient’s clinical condition, and the potential for natural variability. Delta limits can be expressed as absolute differences (e.g., ±10 mg/dL) or as a percentage change (e.g., ±15%).
- Comparing Results: When a new test result is generated for a patient, the laboratory’s information system automatically calculates the difference between the new result and the previous result for the same analyte.
- Delta Check Analysis: The calculated delta (difference) is compared to the predefined delta limits. If the delta exceeds these limits, it triggers an alert or flag in the laboratory’s information system.
- Investigation and Verification: Laboratory personnel review the flagged results to determine the cause of the significant change. They may consider factors such as sample collection errors, instrument malfunctions, changes in patient conditions, medication adjustments, or other clinical reasons.
- Appropriate Action: Based on the investigation, laboratory personnel take appropriate actions. This could involve repeating the test, verifying the patient’s clinical condition, confirming the patient’s identification, checking for instrument calibration issues, or communicating with the healthcare provider if necessary.
Example: Hemoglobin Levels:
Let’s say a patient’s hemoglobin level was tested six months ago and was recorded as 12.5 g/dL. Now, a new test is conducted, and the hemoglobin level is 15.2 g/dL. The delta check is applied to compare the current result with the previous result.
If the predefined delta limit for hemoglobin is ±1.0 g/dL (indicating an acceptable change of up to 1.0 g/dL), the difference between the previous result (12.5 g/dL) and the current result (15.2 g/dL) exceeds the limit (2.7 g/dL). This would trigger an alert for laboratory personnel to review the results and determine the reason for the significant change.
In this scenario, a potential reason for the significant increase could be a sample collection or testing error, a real physiological change, or another factor that needs to be investigated and resolved.
In summary, the delta check is a valuable quality control practice that helps identify and address unexpected variations in patient test results. It enhances the accuracy and reliability of clinical laboratory data and contributes to patient safety and effective healthcare decisions.
About the author
Dr. Sambhu Chakraborty is a distinguished consultant in quality accreditation for laboratories and hospitals. With a leadership portfolio that includes directorial roles in two laboratory organizations and a consulting firm, as well as chairmanship in a prominent laboratory organization, Dr. Chakraborty is a respected voice in the field. For further engagement or inquiries, Dr. Chakraborty can be contacted through email at director@iaqmconsultants.com and info@sambhuchakraborty.com. Additional resourcesand contact information are available on his websites, https://www.quality-pathshala.com and https://www.sambhuchakraborty.com, or via WhatsApp at +919830051583
Thanks for the great blog.
What’s the time interval over which the Delta check is valid?
What’s the criteria to define Delta check limits?
Thank you so much sir for a insightful knowledge. Please put some light on MU also.