Use of clinical laboratory test results in diagnostic decision making has become an integral part of clinical medicine. More than 60-70% of the most important decisions on admission, discharge, and medication are based on laboratory test results. With this high degree of influence, the reliability of laboratory testing and reporting is of utmost importance. Even though automation, standardization and technological advances have significantly improved the analytical reliability of laboratory tests, lab errors still do occur in the pre-analytical, analytical and post-analytical processes of the total testing process. It is the responsibility of the lab manager to minimize lab errors occurring at any stage of the testing process. Lab errors lead to sample rejection which in turn calls for repeat sample collection and analysis, and thereby cause delays in reporting the test results. Any delay in test results could have adverse consequences on the patients health. Monitoring and control of lab errors is therefore an important challenge in the management of clinical labs so as to produce reliable test results as soon as possible and thereby achieve better lab performance.
Quality control refers to the process of detecting analytical errors within the lab to ensure both the reliability and accuracy of test results in order to provide the best possible patient care. Unreliable performance can result in misdiagnosis, delayed treatment and increased costs due to retesting etc. It is therefore of great importance to ensure all results provided are both accurate and reliable. Many instrument and reagent manufacturers assign their own control values based on a very limited number of results, this leads to large standard deviations and subsequent unrealistic wide ranges. In fact target ranges are often so wide that the laboratory is unlikely to fall outside them regardless of their performance. In addition to this manufacturers often use the same raw materials in their reagents, quality controls and calibrators as such there is an increased risk that a shift in patient results will go unnoticed as the manufacturers own QC will appear fine. Totally independent laboratories are required to generate genuinely independent, multi-method, and multi-analyzer data
The Importance of Instrument Calibration in Clinical Lab Testing.
Testing Effective instrument calibration should be viewed as the foundation of all laboratory patients testing. It's the first step to producing reliable patient results and assuring instrument performance. This is the reason laboratories should be paying closer attention. Calibration is used to establish a reference point that assists instruments to produce accurate results. All instruments of measurement, whatever they measure, require calibration. Even everyday items, such as kitchen scales for food preparation, require calibration. The same principle applies to laboratory analyzers but instead of using weights, labs run calibrators or 'standards' with a known concentration. During calibration the lab programmes the instrument with the concentration of each analyte according to the information provided on the kit insert supplied with the calibrator. The instrument then measures the calibrator and adjusts the reading to match the given values.
Four steps to choosing an appropriate calibration
Use a third party calibrator, with independently assigned values, and which is not optimized to work with any specific instrument or reagent system. Use a calibrator with the same matrix as a patient sample. (For example when calibrating urine chemistry tests ensure you choose a urine based calibrator) Use a multi-analytic calibrator with a long shelf life, this will save your lab time and money. Use a calibrator that is completely traceable to reference materials. This ensures comparable and accurate test results. It's important to know when to recalibrate. To ensure your instrument is establishing a reliable baseline and you are building a strong foundation for accurate patient results, frequent recalibration is recommended.
Five steps to successful laboratory calibration.
Follow the instrument or reagent manufacturer's instructions for calibration. If not available, choose a frequency that is dictated by your internal QC frequency. Assess the required frequency of calibration when validating assays. Depending on the stability of the assay it may be necessary to recalibrate more/less frequently. Re-calibrate every time a reagent batch is changed, unless you can demonstrate that changing reagent lot numbers does not adversely affect control values and patient results. Re-calibrate when your QC results are showing a systematic bias- calibration can eliminate trends or small analytical bias. Re-calibrate after major instrument maintenance, such as lamp changes, which can cause shifts in QC values. By following these guidelines, you can be assured your laboratory equipment is properly calibrated and the foundations for accurate patient results are in place.
TOTAL TESTING PROCESS
An understanding of the most critical steps in the total lab testing process is a pre requisite for setting up a plan for a corrective and preventive strategy aimed at minimizing lab errors and safeguarding the patients. Total testing process is a multi step process that begins and ends with the needs of patients. It consists of three major phases:
Pre-analytical phase: The pre analytical phase deals with the collection of specimens from patients and submitting them to the lab.
Analytical Phase: The analytical phase involves testing, examination; analysis and interpretation of the investigations.
Post Analytical Phase: The post-analytical phase deals with giving the test reports to the clinicians and their patients.
Tests Ordered (Clinicians): This phase starts when a clinician orders tests for her/his patients and ends with the lab receptionist preparing work orders for the phlebotomists for specimen collection.
Specimen Collection: This phase starts with the phlebotomists picking up their work orders from the lab receptionist, preparing bar-coded labels, collecting specimens from patients, and submitting samples to the analytic section of the lab for testing. This phase is known to account for almost 70 % of all lab errors, since many specimen fail to pass sample integrity, often leading to their rejection. Hemolysed blood is the most common. Hemolysis is the breakage of red blood cells causing the release of hemoglobin and other internal components into the blood serum or plasma. It can occur both in-vitro and in-vivo. In-vitro hemolysis happens mostly as a result of inappropriate blood collection practices, and is easily detected by the presence of pink or red color specimens in the sample. Other major reasons for sample rejection are insufficient sample quantity, lipemic, icteric, and clotted samples
Sample preparation: Sample processing in the lab may involve centrifugation, aliquotting, pipetting, dilution, etc. Sample adequacy, a critical pre-analytic factor, affects test result accuracy and usefulness. Accepting samples unsuitable for analysis can lead to erroneous information that could compromise patient care.
Testing: After ensuring sample integrity, the lab technicians carry out tests and examinations of the samples as ordered by the clinicians.
Test Result Validation: This phase deals with activities within the laboratory including technical and medical validation of the test results, the production of test reports, interpretation of test results, and its transmission to the requesting clinicians and their patients.
Diagnosis (Clinicians): These activities occur outside the laboratory such as the clinician's reaction to the report, and interpretation and utilization of laboratory information for diagnosis and treatment.
Laboratory errors may be defined as "any defect from ordering tests to reporting results and appropriately interpreting and reacting on these". Many lab managers believe that lab errors are infrequent in their lab and hence no need for a continuous monitoring and/or recording of lab errors. Such an assumption has serious drawbacks, as wrong lab reports could have adverse impact on patients' health. Lab errors occur in each phase of the Total Testing Process. Phlebotomy errors account for a majority of errors in the pre-analytic phase, lack of quality assurance could lead to wrong test results in the analytic phase, while misidentification errors are common in the post-analytic phase. Lab errors also occur at various stages; before sample collection, during sample collection, transportation of the sample to the lab, centrifugation, analysis, and after test results are obtained (certain readings are extreme, out of range) etc. Lab errors, as and when detected call for sample rejection. Any rejected sample calls for repeat sample collection and analysis leading to delayed reports, and additional costs to the lab, besides impacting service quality and customer satisfaction. It is also possible that some lab errors could even go undetected and thereby could adversely affect the patients' health due to incorrect treatment protocol. Consequences of lab errors, therefore, have implications on finances, service quality, and additional training inputs to lab staff. In short, lab errors cut the profitability margin of the laboratory, and therefore minimizing lab errors is a major task in lab management. Monitoring and control of lab errors is very central to an effective and efficient management of lab activities. Effective management is an indicator of producing reliable test results. Efficient management is an indicator of costs incurred for producing reliable hence controlling lab errors is very central to an effective and efficient management of lab activities. Effective management is an indicator of producing reliable test results. Efficient management is an indicator of costs incurred for producing test results. The words sample and specimen are used interchangeably in the literature. Any biological material taken from our body is called a specimen, while it is called a sample when submitted for analysis.
Author is Microbiologist STDC Srinagar