Presentation on theme: "Levey-Jennings Activity Objectives"— Presentation transcript:
1 Module 6 Lab Exercise I: Quality Control and Construction of Levey-Jennings Charts
2 Levey-Jennings Activity Objectives At the completion of this activity, you will be able to:Perform statistical analysis on analyte values from the previous month’s control values, both normal and abnormal levels, to determine Mean, SD, %CV.Draw a Levey-Jennings chart, label the x and y axis correctly, and properly label the LJ chart for documentation and filing.Plot current month’s values daily and evaluate LJ chart for Westgard single rule violations, trends, shifts.Discuss the necessity of Quality Control Result documentation and how they assess precision and accuracy.Trainer Note: This activity has been used in TOT workshops with great success. By having the participants actually take the numbers and determine the Mean, 1Std Dev, %CV, and 1, 2, 3 value ranges, they gain confidence and understanding of constructing, plotting, and interpreting quality control with respect to why they are running control materials with each patient(s) specimen(s).Here are the steps used to direct participants to be successful with this activity:Participants may either work individually or in groups of (Pairing stronger with weaker participants is advantageous to learning for both).Give graph paper to each group along with a small set of colored pencils to be used in the construction of the charts
3 Quality Control Exercise #1 Quality control sample measurement is used to test the analytical phase of patient testing.This first exercise provides quality control sample results to calculate statistics and establish a Levey-Jennings chart.NOTE:Quality control samples are tested along with patient samples to monitor the validity of the analysis.If quality control samples which have a known concentration do not give expected results, it can often mean an error occurred that affected patient results as well.
4 Last Month’s QC Values (Glucose mg/dL) For Establishing the QC Ranges Day168Day 880Day 15282Day 975Day 16Day 379Day 10Day 1770Day 469Day 1177Day 1878Day 5Day 12Day 1973Day 6Day 1374Day 20Day 7Day 1472Calculate the Mean: __________Calculate Std Dev: __________Calculate %CV: __________Determine+ 3 SD Range: ____________5. Construct graph & plot all pointsYou may use any analyte you choose; I used Glucose for example purposes only.Answers to questions 1-5:Mean = 74.7 mg.dL (I rounded all values to one decimal point for ease of graphing)2. Std Dev: 4.83. %CV: 6.4%3SD (99% limits) range: mg/dLI recommend that students use a black pencil to draw the mean line; a green pencil to draw the -+ 1 SD lines; a yellow/orange pencil to draw the -+ 2 SD lines, and a red pencil to draw the -+ 3SD lines. (green line means go with (accept) the value; yellow/orange line is a warning line (accept value but watch carefully next few days); and red line means stop (and investigate)
5 Instrument: _________________. Test: ____________________ Instrument: _________________ Test: ____________________ Units: ________ Method: ____________________ Month/Year: ______________ Tech: ________ Control: ____________________ Lot #: ____________________ Exp: _________ Control Mean: _______________ 1 Std Dev: ________________ SD Range: ___________1234567891011121314151617181920+ 3s+ 2 s+ 1 sMeanYou may copy this form to give to participant(s) for them to use or you may give them purchased regular graph paper.To grade this activity:Plotting all points = 5 points (use glucose data with units from slide 3)Connecting the points = 2 pointsFilling in Instrument, Test, Units (at top of sheet)= 2 points (Instructor should assign an instrument name.)Filling in Method, Month/Year, Tech (at top of sheet) = 2 points (Instructor should assign a method name and have them use current month, year and their name)Filling in Control, Lot #, expirey date = 2 points (Instructor should assign this information)Filling in Control mean, 1 Std Dev, -+3 SD Range (at top of sheet) = 2 points (This is determined from calculations directed on slide 3)Total possible points = 15 pointsI also go around the group asking how often controls should be run. When a Tech answers once a week, I then ask if they had a sick child would they take their son/daughter to their lab or rather to a lab that runs controls daily / with each batch of patient specimens? The importance of LJ charts hits home when students think about the value of QC on a personal level!For an extra assignment you can assign different groups a LJ chart using made-up control values that will show a trend, shift, etc….. They can earn points as in this assignment and show-and-tell their new charts with the class. I found the more hands-on practice students get, the more they understand. Even if the lab they go to work in has automated equipment with built in QC charts, the understanding comes from the hands-on experience.- 1 s- 2 s- 3 sDays
6 Now Plot the following QC Values (Glucose mg/dL) Day175Day 880Day 1568273Day 9Day 16Day 378Day 1077Day 1770Day 469Day 11Day 1879Day 5Day 1282Day 19Day 6Day 1374Day 20Day 7Day 14726
7 This is what the LJ Chart should look like including plotted data
8 Exercise #2 Evaluate the following QC chart by identifying out of control data, outliers, shifts, and trendsAs time permits, this slide can be copied and given to participants to complete. At a later time, this can be pulled out and discussed and will hopefully spur a lively discussion
9 Key QC Lecture Activity #2 Days 9-16 show an upward trend. Patient results should be rejected on day 16 because of systematic error and the cause of the problem needs to be investigated and resolved. Document the problem and solution to the QC problem. Day 17 shows a +3 SD random error*****. Reject patient results, document and resolve the problem. Day indicates a shift in the mean and results should be rejected on day 24, documented and problem resolved. Day 26 is a warning for possible error. Day 27 shows a systematic error of low results, patient results should be rejected, documented and problem resolved.*****Day 17 is probably NOT a random errors but the continuation of a systemic error that is now out of control. A deteriorating light source looks just like this3 circled areas and 2 pointers note analytical problems shown by patterns of QC results. What are they?