In the dynamic field of medical testing, particularly within the biochemistry discipline, adhering to ISO 15189:2022 standards is crucial for ensuring the accuracy and reliability of test results. This standard, especially clause 7.3.7.2 regarding Internal Quality Control (IQC), outlines rigorous procedures for maintaining the validity of examination results crucial for clinical decision-making.
Implementing IQC Procedures with Clinical Consideration: A biochemistry laboratory must have a robust IQC procedure to validate the ongoing accuracy of results, like verifying the consistency of glucose measurements for diabetic monitoring. For instance, if the lab is assessing glucose levels for diabetic patients, the clinical implications of hyperglycemia versus hypoglycemia must be considered, as the performance specifications for glucose can differ in a fasting patient compared to one with diabetic ketoacidosis.
Detecting Reagent or Calibrator Variations: The IQC procedures should account for potential variations in reagents and calibrators. For example, when a new lot of reagents for cholesterol testing is introduced, the lab should avoid changing the IQC material in the same run. This is to ensure any variation can be attributed to the new reagent lot rather than a simultaneous change in the control materials.
Utilizing Third-Party IQC Materials: Third-party IQC materials can provide an independent assessment of the test system’s performance. A biochemistry lab might use third-party control materials for liver function tests, such as ALT and AST, to validate the results independently of the reagent supplier’s controls. This can be particularly useful when the reagent supplier’s control does not offer the necessary level of challenge to the test system or does not react in a way that’s representative of patient samples.
Selecting Fit-for-Purpose IQC Materials: Selecting the appropriate IQC material is critical. For tests like electrolyte analysis, the IQC material should be stable, have a matrix similar to patient samples, and react to the testing method as patient samples would. Moreover, it should provide a clinically relevant challenge, such as having concentrations at critical decision points like the high and low limits for sodium or potassium, which are vital in assessing conditions like hypernatremia or hypokalemia.
Monitoring Interpretations and Opinions: In addition to these controls, laboratories can ensure the validity of interpretations and opinions through regular peer review. For example, when reporting on thyroid function tests like TSH, free T3, and free T4, peer review can help verify that the interpretation aligns with clinical presentations and established reference ranges.
Alternative Methods for IQC:
- Trend Analysis of Patient Results: Laboratories can perform trend analysis, such as employing a moving average of patient results or tracking the percentage of samples with results beyond certain clinical thresholds. For instance, tracking HbA1c levels across patients over time can highlight trends that may indicate a systematic issue with the test method.
- Comparison with Alternative Procedures: Regularly comparing patient results with those obtained from alternative validated procedures can ensure consistency. For example, glucose measurements obtained via a point-of-care device can be periodically cross-checked with results from a central lab analyzer that adheres to higher-order reference standards.
- Retesting of Retained Samples: Laboratories might retest retained patient samples, especially when there is a suspicion of an error. If a particular batch of lipid panels yields unusually high triglyceride values, retesting stored samples can help confirm if the anomaly is due to a testing error.
Frequency and Review of IQC:
- IQC should be conducted at a frequency justified by the stability of the test method. For a robust assay such as serum creatinine, the frequency may be less than for a more volatile measurement like blood gases, where rapid changes can occur.
Data Recording and Analysis:
- Data must be recorded in a way that allows for the detection of trends and shifts. Statistical methods, such as Levey-Jennings charts, can be utilized to monitor enzyme activity levels over time, ensuring any drift is promptly identified and addressed.
IQC Review and Acceptability Criteria:
- IQC data should be reviewed against predefined criteria at regular intervals. If enzyme assays, for instance, consistently fall outside of these criteria, immediate review and corrective action are necessary.
Prevention of Result Release on IQC Failure:
- If IQC does not meet acceptability criteria, indicating significant errors, the lab must halt the release of patient results. All samples tested since the last successful IQC should be re-examined once corrections are made, ensuring no erroneous results are reported.
By adhering to these comprehensive practices outlined in ISO 15189:2022, biochemistry laboratories can ensure the reliability of their results, thereby safeguarding patient health and maintaining the highest standards of laboratory quality and performance.
Through careful application of ISO 15189:2022’s IQC requirements, biochemistry laboratories can bolster their quality assurance processes, providing clinicians with results that they can trust for making informed decisions on patient care.
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 chairman of IOL ( An ILAC stakeholder organisation), 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 resources and contact information are available on his websites,https://www.quality-pathshala.com and https://www.sambhuchakraborty.com or via WhatsApp at +919830051583
Thanks Dr. For your great explanation and support to lab staff, may you please also talk about the most important point in laboratory as most lab’s fail to pass it which is ” Calculation of Muserment uncertainty”
Thank you doc. The new ISO seems to be more aligned to patient care derived from quality results released by labs. IQC reviews I agree will play a major role in control labs from releasing erratic patient results.
Your blogs are very informative and would really love to work with you if given opportunity.
Sir very useful for the QA in hospital labs.. kindly update with trainings and workshops