QP-13: Coagulation Applications
with Internet Quality-Planning Tools
with Internet Quality-Planning Tools
with Internet Quality-Planning Tools |
|
I've saved the best till last! Here are some quality-planning applications for coagulation tests performed on an automated coagulation analyzer that provides three levels of controls and on-line support for data calculations, display of control charts, and flagging by selected QC rules. Looks like an automated chemistry analyzer to me, which makes it easy to apply similar planning and implementation strategies!
Another important aspect of these applications is the availability of new Internet tools that can be used to prepare the OPSpecs charts. These Internet tools are very simple to use - you just put your numbers in the data-entry boxes and click the button to prepare the OPSpecs charts. As with our earlier tools that support QC training and Method Validation calculations and plotting, these tools demonstrate the power and usefulness of the Internet for education and training in analytical quality management.
Two tools are available - the Method Planner and the QC Planner. These tools run on the server, which means that the input data are sent back to another computer (the server) to be processed, then results are returned to your screen.
Try it! Enter an allowable total error of 15% and select three control materials. Click the button to get the OPSpecs chart. For a 13s control rule, you'll see the x-intercept defines the maximum allowable CV as 3.0%. Click here to try the Method Planner now!
Try it! Enter an allowable total error of 15%, method imprecision of 5% and bias of 1%, and three control materials. You'll find a solution on the 3rd chart which is the N=6 OPSpecs chart having 50% AQA(SE). Click here to try the QC Planner now!
CLIA includes criteria for acceptable performance for three coagulation tests in its hematology category:
- Prothrombin time Target value +/- 15%
- Partial thromboplastin time Target value +/- 15%
- Fibrinogen Target value +/- 20%
The example tests presented here are being performed by an automated coagulation analyzer. Routine QC data are available from four different control materials. One material is used for all three tests, two materials are used only for PT and PTT, and one material is used only for fibrinogen.
- Material 1 CVPT=2.6%, CVPTT=2.3%, CVfibrinogen=3.2% (at 273 mg/dL)
- Material 2 CVPT=3.3%, CVPTT=2.3%
- Material 3 CVPT=3.7%, CVPTT=2.6%
- Material 4 CVfibrinogen=5.2% (at 96 mg/dL)
The average CV for PT is 3.2%, the average CV for PTT is 2.4%, and the average CV for fibrinogen is 4.2%.
The laboratory has two of the automated coagulation analyzers, which are routinely compared to minimize any biases between them. Therefore, for practical purposes, the inaccuracy can be considered as zero.
If you are looking at these examples on the Internet, you can access the QC Planner tool directly, enter the values, and work through the OPSpecs charts. For hardcopy document and off-line study, the normalized OPSpecs charts are shown.
NOTE:
- The QC Planner Tool is available online.
- Normalized OPSpecs operating points can be calculated on this website using the Normalized OPSpecs Calculator. Click here to see the calculator.
- The Normalized OPSpecs charts can be download from this website in PDF format. Click here to download the charts.
The quality requirement is 15%, the observed CV is 3.2%, the observed bias is 0.0%, and three control materials are to be used.
You can enter these values directly into the QC Planner tool now.
- The normalized operating point would have an x-coordinate of 21.3% [(3.2%/15%)100] and a y-coordinate of zero.
- The normalized OPSpecs chart identifies four possible QC procedures, but the 12s rule with N=3 should be eliminated from consideration because of its high false rejection rate (about 14%). The single rule 12.5s may be preferred over the multirule procedure for simplicity, but both provide the necessary error detection.
- The Total QC strategy can depend on the high error detection from statistical QC and should also include the preventive maintenance, instrument function checks, etc., as recommended by the manufacturer, regulatory and accreditation guidelines, and by good laboratory practices.
The quality requirement is 15%, the observed CV is 2.4%, the observed bias is 0.0%, and three control materials are to be used.
You can enter these values directly into the QC Planner tool now.
- The normalized operating point would have an x-coordinate of 16% [(2.4%/15%)100] and a y-coordinate of zero.
- The normalized OPSpecs chart shows that all the possible QC procedures would provide adequate error detection. Again, the 12s rule with N=3 should be eliminated from consideration because of its high false rejection rate (about 14%). the single rule 13s may be preferred over a multirule procedure for simplicity.
- The Total QC strategy can depend on the high error detection from statistical QC and should also include the preventive maintenance, instrument function checks, etc., as recommended by the manufacturer, regulatory and accreditation guidelines, and by good laboratory practices.
The quality requirement is 20%, the observed CV is 4.2%, the observed bias is 0.0%, and TWO control materials are to be used.
You can enter these values directly into the QC Planner tool now.
- The normalized operating point would have an x-coordinate of 21% [(4.2%/20%)100] and a y-coordinate of zero.
- The normalized OPSpecs chart shows two possible solutions, but the 12s rule with N=2 should be eliminated from consideration because of its high false rejection rate (about 9%). The single rule 12.5s should be used; the 13s/22s/R4s multirule procedure is a close second and could be used if it were easier to implement.
- The Total QC strategy can depend on the high error detection from statistical QC and should also include the preventive maintenance, instrument function checks, etc., as recommended by the manufacturer, regulatory and accreditation guidelines, and by good laboratory practices.
The results from the QC Planner tool and the Normalized OPSpecs charts are the same. Note, however, that there is one additional multirule QC procedure being considered on the normalized OPSpecs charts for three materials.
- Unify the QC procedure and TQC strategy when possible to provide simplicity in operation. All three tests here could be controlled using a 12.5s rule, which might make it easier for implementation and training. Not only can the same control rule be used, but also the same TQC strategy.
- Utilize instrument QC software to implement individualized QC designs. Most automated analyzers provide online QC support, but may not include all the control rules considered here. For example, if the 12.5s rule is not available, but multirule support is provided, you could implement QC procedures that provide similar performance. Implement a 13s/2of32s/R4s for PT, 13s for PTT, and 13s/22s/R4s for fibrinogen.
- Utilize Internet quality-planning tools to simplify the quality-planning applications. The simplest tools to use are Internet tools that provide a data-entry form, then a button for executing the next step in the process. For periodic use and infrequent users, Internet tools may be the most practical.
