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Shift and Trend Analysis in Medical Laboratory Quality Control: Monitoring Accuracy and Reliability

By Dayyal Dg.Twitter Profile | Updated: Thursday, 29 June 2023 17:22 UTC
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Chemist nurse explainig to doctor vaccine development in modern laboratory.
Chemist nurse explainig to doctor vaccine development in modern laboratory. Freepik / @DCStudio

Optimize your medical laboratory quality control with shift and trend analysis. Detect variations in test results for accurate diagnostics. Ensure reliability and patient safety.

Quality control (QC) is an essential aspect of medical laboratory testing, ensuring accurate and reliable results for patient care. Within QC, the concepts of shift and trend analysis play a vital role in monitoring the performance of laboratory testing processes over time. Understanding the difference between shift and trend is crucial for identifying variations, investigating potential issues, and implementing corrective actions promptly. This article explores the significance of shift and trend analysis in medical laboratory QC and their respective implications.

Shift Analysis

A shift in QC refers to a sudden, significant deviation from the established mean or target value. It represents an abrupt change in test results, often caused by various factors such as instrument malfunction, changes in reagents or calibrators, operator errors, or environmental influences. Detecting shifts is crucial because they can indicate problems with the analytical system, which may affect the accuracy and reliability of patient results.

To monitor shifts, laboratories employ statistical process control (SPC) techniques, including control charts such as Levey-Jennings charts. These charts plot QC data over time, allowing visual identification of deviations from the mean or target value. When a shift occurs, it stands out as a data point or series of points that fall outside the acceptable control limits. Prompt detection of shifts enables laboratories to investigate the root cause, take corrective actions, and prevent further inaccurate results from being reported to healthcare providers.

Trend Analysis

Unlike shifts, trends in QC represent a gradual, systematic change in test results over time. They indicate a slow drift away from the target value and are typically caused by factors such as instrument aging, reagent degradation, changes in environmental conditions, or inadequate calibration. Monitoring trends is essential for identifying long-term shifts that might not be evident from analyzing individual data points.

Trend analysis also relies on SPC techniques and control charts, such as moving average charts. These charts display the average of a specific number of consecutive data points over time. By observing the movement of the average line, laboratories can identify trends that show a consistent upward or downward direction. Detecting a trend early allows for timely corrective actions, preventing significant deviations from the target value and ensuring the accuracy and reliability of patient test results.

Importance of Shift and Trend Analysis

Shift and trend analysis are crucial components of medical laboratory QC as they provide insights into the stability and reliability of testing processes. By continuously monitoring shifts and trends, laboratories can:

  1. Ensure Accuracy: Prompt detection and investigation of shifts help identify and rectify problems that may compromise the accuracy of test results. Addressing these issues ensures that patients receive reliable diagnostic information for proper medical treatment.
  2. Enhance Patient Safety: By promptly identifying and resolving shifts and trends, laboratories contribute to patient safety. Accurate and reliable test results are essential for making informed clinical decisions and providing appropriate patient care.
  3. Improve Process Efficiency: Analyzing shifts and trends allows laboratories to identify areas for process improvement. By addressing the root causes of deviations, laboratories can optimize instrument performance, reagent usage, calibration protocols, and other aspects of the testing process, leading to increased efficiency and productivity.
  4. Comply with Quality Standards: Shift and trend analysis align with quality management systems and accreditation requirements for medical laboratories. These practices demonstrate a commitment to continuous quality improvement and adherence to internationally recognized standards.


Shift and trend analysis are integral to medical laboratory QC, providing valuable insights into the accuracy and reliability of test results. By monitoring shifts and trends through statistical process control techniques, laboratories can promptly detect deviations from the target value and take corrective actions. This proactive approach enhances patient safety, ensures accurate diagnoses, improves process efficiency, and demonstrates adherence to quality standards. By implementing robust shift and trend analysis practices, medical laboratories can maintain the highest standards of quality and contribute to improved healthcare outcomes.

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