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Quality Control


Quality Assurance Is the policies, procedures, and activities required to ensure that patient care is delivered appropriately and with high quality.
Quality Assurance In the laboratory requires that test data be accurate and reliable reflecting the true status of the patient so that medical practitioners may rely on the data in making informed patient care decisions.
Quality Control Formal, documented methods of monitoring performance of laboratory personnel, instruments, reagents, products, and equipment to assure accuracy and precision of assay data.
Accuracy: Closeness to the truth.
Precision: Repeatability
Standard A substance that has an exact known value and that, when accurately measured, can produce a solution of an exact concentration.
Standard Used to calibrate new instruments, recalibrate instruments after repair or maintenance, at manufacturer’s recommended intervals, or if a method is out of control
Control A solution that contains the same constituents as those being analyzed in the patient sample.
Control Require a low, normal, and high control. This practice monitors an instrument’s accuracy and precision along a range of assay concentrations.
Controlled Runs Each group of specimens tested (batch) must include controls. If the controls are within the accepted test range, the accuracy of the results obtained from each patient sample in the batch is reasonably assured.
Controlled Runs If, however, the control samples are outside the accepted test range (out of control), the patient test results are invalid and, therefore, test results will not be reported to the physician until the controls are within range.
Duplicate Testing A patient sample from each batch may be randomly selected for a repeat test to monitor precision. It is a prudent practice to repeat all patient sample tests that are abnormal, even if the batch is in control.
Control Charting Quality control chart such as a Levey-Jennings chart.
Mean Arithmetic average.
Standard Deviation Measures how far the data, as a whole, varies from the mean.
In Control (Normal) Variation Data points will vary equally above and below the mean of the control range. Data points will be consistent with the areas under the normal curve. None of the points should be beyond 3 standard deviations of the mean.
Common Causes of Variation Mistakes in measurements, calculations, or documentation. Changes in process. Change of technicians. Changes in supplies and equipment. Defective controls. Improper testing
1-3s: A single point beyond 3 SD indicating a significant change in a process.
4-1s: Four consecutive points on the same side of the mean are beyond 1 SD of the mean.
2-2s: Two consecutive points on the same side of the mean are beyond 2 SD of the mean.
Trend: Seven or more consecutive points traveling in the same direction indicating that a gradual change is occurring.
Shift: Seven or more consecutive points on one side of the mean.
Created by: itsdelis