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Quality Control

Garland Pendergraph, Ph. D. (Doctors Lab Inc.)

Quality Control is a comprehensive course in QC terminology, practices, statistics, and troubleshooting for the clinical laboratory. Designed for those who have little or no experience with quality control but need a firm grounding, this course will help all students quickly and easily identify and correct errors in quality control procedures. Concepts covered include: running assayed and unassayed controls, specificity, sensitivity, Westgard rules, Levey-Jennings charts, Youden plots, and CUSUM calculations. MediaLab also offers an "Introduction to Quality Control" course to complement the more detailed and thorough presentation in this course.

Continuing Education (CE) Credits

P.A.C.E. Contact Hours: 2 hour(s)
Florida CE: Quality Control: 2 hour(s)

Other Quality Control & Lab Math Courses

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Quality Control Objectives

Introduce quality control terminology.
Explain quality control graphical tools, including GAUSSIAN curves, LEVEY-JENNINGS charts, CUSUM CALCULATIONS, and YOUDEN plots.
Detail WESTGUARD rules used to identify QC problems.
Provide practical examples of QC in LABORATORY ENVIRONMENTS.
Give suggestions for troubleshooting quality control errors.

Quality Control Outline

Definition of Quality Control

What is Quality Control?

Important Concepts in Quality Control

Controls

What is a Control?
SAFETY and Handling of Controls
Appearance of Controls
Why Run Controls?
ASSAYED and UNASSAYED Controls
Controls should be run every day that testing will take place.
What is an UNASSAYED control?

Precision and Accuracy

Aiming for the Target
Closer, but not Quite
Bullseye!
A lab tech is running GLUCOSE an ASSAYED control. The manufacturer has determined the control to have a value of 95. The lab tech runs the GLUCOSE test ten times, producing the following results: 99, 99, 99, 98, 98, 98, 98, 97, 97, 97. In which area should the lab tech try to improve his skills?

SPECIFICITY

Calculating SPECIFICITY
SPECIFICITY Example
SPECIFICITY Example: Test Results
SPECIFICITY Example: CALCULATIONS (1)
SPECIFICITY Example: CALCULATIONS (2)
SPECIFICITY Example: Comparison
Based on the data for the experimental and tried-and-true PROCEDURES, which test would produce fewer false negatives?
Using the data and formula to the right, we can calculate SPECIFICITY of the West Nile VIRUS test to be:

SENSITIVITY

Calculating SENSITIVITY
SENSITIVITY Example: CALCULATIONS (1)
SENSITIVITY Example: CALCULATIONS (2)
SENSITIVITY Example: Comparison
Based on the data for the experimental and tried-and-true PROCEDURES, which test would produce fewer false positives?
SPECIFICITY vs. SENSITIVITY
Using the data and formula to the right, we can calculate SENSITIVITY of the West Nile VIRUS test to be:

Standards and CALIBRATORS

What are Standards and CALIBRATORS?
CALIBRATION Curve
LINEARITY
LINEARITY Example
Non-linear CALIBRATION Curves
Which of the following meets the strict definition of LINEARITY given by PLAUT?

Random and SYSTEMATIC ERROR

Types of Error
RANDOM ERROR
SYSTEMATIC ERROR
Causes of Error
Indicate which of the problems in the list below are more likely to be RANDOM ERRORS or SYSTEMATIC ERRORS.

Internal and External Quality Control

Internal Quality Control
External Quality Control (1)
External Quality Control (2)
External Quality Control (3)
Comparing Types of Quality Control
Match the type of quality control to the benefits it provides.

Reference Ranges

Reference Ranges

Quality Control PROCEDURES, Documentation and Interpretation

Basic Terms

Overview of STATISTICS
Mean
HISTOGRAMS
STANDARD DEVIATION
Acceptable STANDARD DEVIATION
In a normal distribution, what percent of data would be more than +/- 3 STANDARD DEVIATIONS from the mean?

LEVEY-JENNINGS Chart

The LEVEY-JENNINGS Chart's Inventors
What is a LEVEY-JENNINGS Chart?
On which days did the control data fall at least one STANDARD DEVIATION from the mean?

WESTGUARD Rules

Using WESTGUARD Rules
WESTGUARD Rule 13S
WESTGUARD Rule 22S
WESTGUARD Rule 41s (1)
WESTGUARD Rule 41s (2)
Does the LEVEY-JENNINGS chart to the right show acceptable quality control results?
Does the LEVEY-JENNINGS chart to the right show acceptable quality control results?
Trends
Shifts

Cumulative Summation Limit

What is a Cumulative Summation Limit?
CUSUM Example: Plotting Control Data
CUSUM Example: Calculating CUSUM
CUSUM Example: Exceeding the CUSUM Limit
CUSUM and WESTGUARD Rules

YOUDEN Plot

What is a YOUDEN Plot?
Using a YOUDEN Plot
In the accompanying YOUDEN plot, what conclusions can be drawn about the data?

Systematic Troubleshooting

Troubleshooting
Possible CORRECTIVE Action (1)
Possible CORRECTIVE Action (2)
Possible CORRECTIVE Action (3)
Possible CORRECTIVE Action (4)
Possible CORRECTIVE Action (5)
Put the troubleshooting steps below in the order in which they should be tried.

Establishment of Verification of Method Performance Specifications

What is NON-WAIVED Testing?
Verification for NON-WAIVED Testing

Quality Control Problem

A Quality Control Exercise
Control Testing Results
In this example GLUCOSE run. possible RANDOM ERRORS occurred on days:
According to the WESTGUARD Rules, the GLUCOSE run should have been rejected on day:

Quality Control Keywords

Click on a term below to see its use in this Quality Control course and other available MediaLab courses.

standard deviation (16 occurances)
systematic error (15 occurances)
laboratory (14 occurances)
random error (12 occurances)
westguard (11 occurances)
specificity (9 occurances)
levey-jennings (9 occurances)
calibration (9 occurances)
analyte (8 occurances)
calculation (7 occurances)
corrective (7 occurances)
linearity (7 occurances)
glucose (7 occurances)
sensitivity (7 occurances)
statistical (6 occurances)
cusum (6 occurances)
youden (6 occurances)
westgard (5 occurances)
virus (4 occurances)
clinical laboratory (4 occurances)
blood (4 occurances)
procedures (4 occurances)
gaussian (4 occurances)
samples (3 occurances)
assayed (3 occurances)
concentration (3 occurances)
disease (3 occurances)
evaluation (2 occurances)
clia (2 occurances)
bottle (2 occurances)
calibrated (2 occurances)
analytes (2 occurances)
analytic (2 occurances)
plaut (2 occurances)
unassayed (2 occurances)
amendment (2 occurances)
hiv (2 occurances)
hematology (2 occurances)
non-waived (2 occurances)