Form for Method Comparison

[Sandy Jo]

Quick! Does anyone have a form they are willing to share (or post in the Library) for method comparison of Blood Bank assays? I would like to include a minimum of 10 patient samples and correlate between Solid Phase (Echo) and tube testing for ABO/Rh and Antibody Screen.

Thanks so much!

Sandy

[David Saikin]

Why would you want to run so many?  Just curious . . .

[Sandy Jo]

That is the quantity we use in other areas of the lab and it is also the quantity used in other facilities in our division. We are standardizing many of the processes so that is what I am using.

Sandy

[R1R2]

8 hours ago, David Saikin said:

Why would you want to run so many?  Just curious . . .

I agree with David.   2 would be enough for me (even 1). 

[mollyredone]

I agree with David and R1R2.  But here is a copy of my comparison form.  I use two positive and 1 negative AB screens and 1 negative and 1 positive DAT every six months for comparison between gel and tube.  

METHOD COMPARABILITY WORKSHEET ABS.xlsx

[exlimey]

On 5/23/2016 at 11:17 AM, Sandy Jo said:

Quick! Does anyone have a form they are willing to share (or post in the Library) for method comparison of Blood Bank assays? I would like to include a minimum of 10 patient samples and correlate between Solid Phase (Echo) and tube testing for ABO/Rh and Antibody Screen.

Thanks so much!

Sandy

Sandy,

How do you deal with discordant results? There's a great difference in sensitivity of the assays you mentioned. Or do you bias the results beforehand by making sure your test samples perform in each system? Not a criticism, just wondering.

[sgoertzen]

I've attached the form I came up with that we use.

Here is the section in my procedure that addresses method correlation:

CAP Checklist: COM.04250

If the laboratory uses more than one nonwaived instrument/method to test for a given analyte, the instruments/methods checked against each other at least twice a year for comparability of results.

 

NOTE: This requirement applies to tests performed on the same or different instrument makes/models or by different methods. This comparison must include all nonwaived instruments/methods. The laboratory must establish a protocol for this check that includes acceptance criteria. Quality control data may be used for this comparison for tests performed on the same instrument platform, with control materials of the same manufacturer and lot number. Otherwise, the use of human samples (whole blood, serum, plasma, urine, etc.) rather than stabilized commercial controls, is preferred to avoid potential matrix effects. In cases when availability or pre-analytical stability of patient/client specimens is a limiting factor, alternative protocols based on QC or reference materials may be necessary but the materials used should be validated (when applicable) to have the same response as fresh human samples for the instruments/methods involved.

 

Method Correlation is performed twice a year, comparing Echo1 vs. Echo2 vs. Manual Capture vs. Tube methods

1.       ABO/Rh – No less than 3 specimens are compared, each with different blood types, at least one should be Rh negative

2.       Antibody Screen – No less than 3 specimens are compared, at least one should be positive

3.       Antigen Typing – comparing tube to Echo, no less than 3 specimens

4.       Antibody ID – No less than 1 positive specimen is compared

Interpretation/ Acceptance Criteria:

·         Manual and Automated Capture methods are expected to correlate closely.

·         Echo1 vs. Echo2 results are expected to correlate (match) closely.

·         Capture vs. Tube methods are expected to show some variability between reactions due to the differences in the nature of the testing systems and enhancements.

·         Corrective action must be taken and documented when criteria are not met.

 

Hope this helps!       Sheri

Q0530F03 Method Correlation 8-12.doc

[AMcCord]

Thanks for sharing Sheri. I like your worksheet a whole lot better than the one I came up with - I'll be making some changes!

 

[Sandy Jo]

23 hours ago, exlimey said:

How do you deal with discordant results? There's a great difference in sensitivity of the assays you mentioned. Or do you bias the results beforehand by making sure your test samples perform in each system? Not a criticism, just wondering.

Basically there is a bias with the selected samples. I would not be picking a patient with a SPD (Solid Phase Dependent) antibody to compare with manual tube methods. We pull samples that have already been run on the Echo and repeat them in tube testing. I also include a "disclaimer" of sorts in the SOP by stating that the methods may not compare 100% due to the sensitivity and specificity of each test method. The goal is not to achieve perfect correlation, but to document comparable results given the difference in sensitivities, specificities and general limitations between the methods. As we all know and love - no one method will always detect all clinically significant antibodies!