IVDT_In Vitro Diagnostics Technology

IVD Technology, Spring 2013

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CLINICAL DIAGNOSTICS minimal as to be clinically insignifcant. Tus, the goal of risk management in the laboratory is to control risk to a clinically acceptable level. Risk can be reduced either by preventing the error from happening or detecting errors once they occur before the error can lead to harm. Hazard identifcation: Predicting the Potential for Harm A frst step in risk management for clinical testing is to create a process map to understand the sequence of steps required to produce and report a test result. Outline the entire analytical process from test order through specimen collection, testing, and reporting of results. Examine the process for weak points where failures or use errors may occur. Tese failure points can cause hazards that create risk for patients or laboratory workers. Some common causes of laboratory hazards include the environment, the operator (use errors), and the analysis (system failures). Environmental errors can occur from exposure to temperature extremes. Reagents and controls can deteriorate when exposed to hot or cold temperatures. Glucose meters, POCT kits and strips, and laboratory reagents can degrade when exposed to hot temperatures during the summer and frozen in the winter. Visiting nurses transporting POCT kits in their cars and airline transportation of reagent packages can expose test components to the environment. Humidity, light, air exposure and even altitude (in the case of blood gases, for example) can be potential sources of erroneous test results. Operator technique can inadvertently lead to erroneous test results through improper specimen collection, preparation, and handling. Patient misidentifcation, specimen mislabeling, collection of specimens in the wrong tube additive, or delays in transporting specimens to the laboratory can lead to incorrect test results. Failure to explicitly follow ivd tech n o lo gy.com magenta cyan black manufacturer directions and incorrect test interpretation can further impact test performance. Incorrect or delayed result interpretation, particularly for manual, visually interpreted tests, can also lead to diagnostic or treatment errors that could afect patient care. Instrument failure also can afect test results. Incorrect calibration factors, dilutions and calculations are possible causes of erroneous results. Tus, there are a number of potential failure modes that can lead to incorrect test results that can be identifed through a detailed process map. Risk assessment: Reducing Risk through the Right QC Once hazards are identifed, risk needs to be controlled. Historically, liquid controls are used to monitor the stability of an analytical system. Te analysis of liquid controls rose out of the 1950 factory model of quality control, where the performance of a test system (the analyzer, reagents, and operator) is monitored by analyzing a stable surrogate patient sample containing a constant amount of analyte. If the control sample produces results within a statistically determined range of variability, then the system is stable and patient results are assumed to be accurate. Liquid quality control does a good job at detecting systematic changes that afect every test result in a constant and predictable manner. Bias or instability caused by incorrect reagent preparation, improper storage or shipment conditions, incorrect operator technique (dilution, pipette setting), or calibration errors can be detected by liquid quality controls, because these errors will afect all test results—patient and QC samples— beginning at the time of the error. However, errors that afect individual samples in an unpredictable manner are not detectable by liquid quality control. Clots, bubbles, and interfering factors like hemolysis or drugs afect single samples. Control samples cannot detect a single hemolyzed patient specimen. What the labora- tory needs is a fully automated analyzer that inspects every test sample and detects such problems, preventing incorrect test results. Until an analyzer can detect all sample quality problems, use errors, and device failures that could afect patient results, the laboratory needs a robust quality control plan to prevent erroneous, potentially hazardous results from being reported. Newer laboratory devices may have built-in system controls and sample integrity checks. Te laboratory needs to fnd the right balance between control mechanisms engineered into the device by the manufacturer and the use of traditional liquid quality control specimens. Some devices have internal checks that are performed automatically with each specimen, such as the development of a separate control line on pregnancy and drug tests. Other checks are engineered into the device, like bar coding of reagents to prevent use past their expiration date. Such checks are designed to prevent specifc failures from occurring but may not detect failures in other parts of the testing process. No single quality control plan can cover all devices, because the potential for device failures or use errors and available control processes may difer. Laboratory directors have the ultimate responsibility for determining the appropriate quality control plans for their laboratories. Manufacturers of in vitro diagnostic devices have the responsibility for providing adequate information about the performance of devices, the means to control residual risks, and the verifcation of performance within specifcation.4 In practice, quality control is a shared responsibility between manufacturers and users of devices.4 Developing a quality control plan for a laboratory testing process requires a partnership between the manufacturer and the laboratory. Some failures may be detected automatically by the device, while others may require the laboratory to take action. For example, quality control I VD T EC H N O LO G Y | S PR I NG 2 0 1 3 3 1 ES235844_IV1305_031.pgs 04.23.2013 05:08 UBM

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