Trm.31450

[lef5501]

Question says "If laboratory uses more than one instument/method to test, are the instruments/methods checked against each other at least twice a year for correlation". Just wondering if this would apply to hospitals using both gel and tube methods. We mainly use gel (manual), but on occasion will use our tubes as backup or just to do a quick blood type. Do we need to be doing correlations between these methods or is this more for instrumentation?

[NedB]

Since Blood Bank tests are usually only graded positive or negative the term correlation cannot be applied. The inspectors will want you to QC both methods, to investigate all discrepancies, and to describe the methods in your procedure.

[Malcolm Needs ☆]

Since Blood Bank tests are usually only graded positive or negative the term correlation cannot be applied. The inspectors will want you to QC both methods, to investigate all discrepancies, and to describe the methods in your procedure.

This is not entirely true NedB (although I do note your use of the word "usually").

There are quite a few occasions when the grading of the reaction is important.

Off the top of my head, there are subgroups of ABO, weak and partial D's, k typing, when the KE02 gene is in trans with a KE03, Fyx, titration end points, to name but a few.

You are, of course, absolutely correct in saying that the inspectors will want you to QC both techniques, but there is slightly more to it than that. There does have to be some correlation between the two, otherwise some of the results will be meaningless.

[clmergen]

Yes, I think this applies in this situation. Semi-annually, we will run a selection of specimens on the Instrument and by tube. The results should be the same.

[lorna]

I'm curious of how many samples labs run each time the correlation tests are performed? We have just started using an alternate method, so we'll need to perform this testing now, and so of course now I wonder....how many every 6 months?

Thanks!

[adiescast]

Because we run our CAP survey samples with both of our methods (tube and solid phase), we take care of this comparison of methods three times a year.

It is important to recall that the enhancement medium used in the tube will affect the results (in terms of reaction strength) and the tube method does not always correlate directly with either solid phase or gel, which are more sensitive than tube. In the end, what you are actually correlating is the positive or negative interpretation. What shows up as 4 + by solid phase may only be 2+ in the tube or may not be detectable at all. We have had antibodies that show up only in solid phase and antibodies that only show up in tube. Correlation of these methods can be a bit subjective.

[NedB]

Malcolm Needs

You probably only have one method of running the tests you mentioned, so what would correlate? We all have more than one kind of antibody screen and antibody identification, but when you validated the methods you decided which were best for which situations. What need is there to correlate these? As I said different situations will require use of different methods and it is important that you have a mechanism in place for investigating discrepancies and changing policies or even procedures if necessary.

[Malcolm Needs ☆]

Because we run our CAP survey samples with both of our methods (tube and solid phase), we take care of this comparison of methods three times a year.

It is important to recall that the enhancement medium used in the tube will affect the results (in terms of reaction strength) and the tube method does not always correlate directly with either solid phase or gel, which are more sensitive than tube. In the end, what you are actually correlating is the positive or negative interpretation. What shows up as 4 + by solid phase may only be 2+ in the tube or may not be detectable at all. We have had antibodies that show up only in solid phase and antibodies that only show up in tube. Correlation of these methods can be a bit subjective.

I agree with everything you say here adiescast, but I think it is well for everyone to remember that there are certain antibodies that will always react more strongly by method, rather than another, or even some that only react using a particular method, and so correlation will never be exact for all antibodies.

We find that we detect an awful lot of anti-M's by gel, partly because of the fact that we are (usually) mixing the reactants at room temperature prior to incubation at 37oc, thus allowing sensitization by a "cold" anti-M prior to incubation, and partly because, if I remember TimOz's post correctly, the pH of or in the gel is slightly lower than that of the phosphate buffered saline and LISS we use for tubes.

We notice a rise in titre of about one dilution when we went to gel, but we also sent out a circular to all the hospital Blood Banks and the hospital Obstetric Units prior to "go live" day, to warn them of this expected change. They were quite happy about it and (for once!) took notice.

[Malcolm Needs ☆]

Malcolm Needs

You probably only have one method of running the tests you mentioned, so what would correlate? We all have more than one kind of antibody screen and antibody identification, but when you validated the methods you decided which were best for which situations. What need is there to correlate these? As I said different situations will require use of different methods and it is important that you have a mechanism in place for investigating discrepancies and changing policies or even procedures if necessary.

Yes, I agree with what you are saying NedB, but even when we were choosing which method to use, we had to perform a change control to ensure that the method was as good, if not better, than the "old" method, and this change control included a corrolation between the "old" and the "new".

In certain cases, there was a corrolation, but the "new" results were different from the "old" results (but consistently so), and in such cases we sent out a warning to the hospitals that there would be this change, before we went over to the "new", so that they would be aware of this change.

[kell23]

Does anyone have a procedure they would like to share for comparrisons between gel and tube testing?

[Malcolm Needs ☆]

Does anyone have a procedure they would like to share for comparrisons between gel and tube testing?

This is not going to be a tremendously helpful post (nothing new there then with my posts), but really it is up to you.

You have to decide for what you are going to use the new technique (be it gel for tube, or tube for gel), and then perform parallel tests with each until you are happy that the new technique is at least as good, if not better, than the old technique (but you have to decide how many comparisons you need to do to be happy about this and record this and the results you obtain).

Sorry.

:redface:

[bevydawn]

Is anyone doing method comparions twice a year as this CAP questions states is necessary? If so, how many patients do you do each time?

[webersl]

Malcolm Needs

You probably only have one method of running the tests you mentioned, so what would correlate? We all have more than one kind of antibody screen and antibody identification, but when you validated the methods you decided which were best for which situations. What need is there to correlate these? As I said different situations will require use of different methods and it is important that you have a mechanism in place for investigating discrepancies and changing policies or even procedures if necessary.

I agree.

[Linda0623]

I am in the process of setting this up myself, and I admit I will be "cheating" a little as I have previously been a chemistry lab supervisor.

My interpretation for this rule in Blood Bank is to be able to prove that your validated use of each method performs as expected, so, that if you use a manual back-up method to your automation, you can be reasonably assured of getting the same results. In this case, it's not necessarily about the individual grading reactions, it's about interpretations, and tolerance between the methods. For example, in Chemistry, we had whole blood sample testing for analytes such as glucose and electrolytes performed in Blood Gas, and plasma testing performed on a different set of analyzers. A ten sample comparison between methods was run. SD applies, it's not about matching exactly. WB testing does range differently than plasma testing, therefore, you build accomodations into it for tolerance in the method comparisons. For example, reproducibility is defined at 10% between runs for glucose. Any outliers are documented and investigated.

This general principle will apply in Blood Bank,.

My intent is to run KNOWN patients (10 of them), both positive and Negative, on Both my ECHO, and in tube(PEG). My tolerance, or acceptability range, will be determined based on the acceptable concordance we achieved during ECHO validation. This will be for Group/Screen, and Panel only, as those are the only processes we routinely run on our ECHO. In the future, when we purchase a 2nd machine, the correlation would be run method vs. method, and analyzer #1 vs. Analyzer #2. The goal was to show that regardless of which method or analyzer was used, the reported results were as expected, or in the case of the analyzer, either one could run a patient and the outcome would be the same.......

I don't know if that helps any, but if anyone has any suggestions, I'd love to hear them!!!

[LaraT23]

We use gel and tubes both manually. In my thinking it is to be expected that they won't correlate all that well. The gel is much more sensitive and not subject to all that much individual interpretation. We in fact were able to purchase the gel after a Jka was missed in the tube and the patient had a lovely DHTR. So, really non correlation is to be expected in my view.

[DPruden]

METHOD CORRELATION OR MADNESS?

By Suzanne H. Butch, MA, MT(ASCP)SBB

First, let me say that quality control is important. As laboratorians, we have a responsibility to

follow federal regulations. Furthermore, we have a responsibility to bring to the attention of our

regulators when there are illogical and time consuming quality control requirements that fail

both the purpose and spirit of quality management. One such example has recently come to my

attention. In the newest (6/15/09) CAP Transfusion Medicine Survey is question TRM.31450 that

asks “If the laboratory uses more than one instrument/method to test for a given analyte, are

the instruments/methods checked against each other at least twice a year for correlation of

results?â€

The question and the explanatory note below is word for word the Chemistry/Toxicology

question CHM.13800: “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 director must establish a protocol for this

check. 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 fresh 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. This checklist requirement applies only to

instruments/methods accredited under a single CAP number.â€

My interpretation of the above is that every six months blood bank laboratories must now

document correlation between all methods used to perform a Type, Screen, Crossmatch and

antibody identification whether by tube, manual or automated microtiter plate, manual or

automated Gel and by different phases. We must document that we get the same answer,

regardless of method.

The rationale behind this CAP question is that correlation studies are a required by CLIA

regulation. This appears to be an unintended consequence of the most recent revision of the

CLIA quality control regulations where individual laboratory requirements were eliminated in

favor of a single set of requirements.

This requirement makes sense when the results being reported vary from day to day and

instrument to instrument. However, blood types do not change without cause. They are not

variable from day to day. In addition, the ABO type is “controlled†by the use of a forward and

reverse grouping. Tube Rh typing result vary by the clone(s), enhancement media, incubation

time, cell suspension and other patient variables. It is well known that the various methods

used for antibody detection and identification have differences in sensitivity and specificity. In

addition, some antibodies are only recognized under very specific circumstances. No two

antibody detection/identification methods get the exact same results. In fact, we employ this

variation in methods to obtain different results when we use enzymes, PEG, LISS, etc. to help us

problem solve when a patient has multiple antibodies, non-specific reactivity, and warm and

cold auto antibodies.

The most important “control†we do in the transfusion service is the history check. We do this

for every patient. If we find a discrepancy, we investigate. Doing a method comparison every six

months will not improve patient care. Applying what is a rational requirement when doing

biochemical tests to the serologic results produced by immunohematology testing is not

appropriate. If the method comparison was easy to perform, one might decide to just comply. In

this case, however, meaningful testing is cumbersome, difficult to structure and execution is

expensive to execute. Significant time and resources would need to be devoted to this task.

Testing enough samples to provide a valid comparison of methods is time consuming and

illogical.

The references given for this new requirement are based on biochemical and hematological

studies:

1) Department of Health and Human Services, Centers for Medicare and Medicaid Services.

Medicare, Medicaid and CLIA programs; CLIA fee collection; correction and final rule. Fed

Register. 2003(Jan 24):5236 [42CFR493.1281(a)]

2) Podczasy JJ, et al. Clinical evaluation of the Accu-Chek Advantage blood glucose monitoring

system. Lab Med. 1997;28:462-466

3) Ross JW, et al. The accuracy of laboratory measurements in clinical chemistry: a study of

eleven analytes in the College of American Pathologists Chemistry Survey with fresh frozen

serum, definitive methods and reference methods. Arch Pathol Lab Med. 1998;122:587-608

4) Miller WG, Myers GL, Ashwood ER, et al. State of the Art in Trueness and Inter-Laboratory

Harmonization for 10 Analytes in General Clinical Chemistry. Arch Pathol Lab Med 2008;132:838-

846

5) Clinical and Laboratory Standards Institute. Verification of comparabililty of patient results

within one healthcare system: Approved Guideline. CLSI document C54-A (ISBN 1-56238-671-

9).Clinical and Laboratory Standards Institute, 940 West Valley Road, Suite 1400, Wayne,

Pennsylvania 190871898, USA, 2008.

For those of you who share my opinion and believe the arguments against method correlation

on a 6 month basis are cogent, please write Judy Yost Director, Center for Laboratories US Dept

of Health & Human Services Commission on Medicare & Medicaid Baltimore, MD or CLIA staff at

(410) 786-3407 or (410) 786-3531. Her email is Judith.yost@cms.hhs.gov . I have heard her

speak and she is a proponent of reasonable and effective quality control.

[Malcolm Needs ☆]

A true tour de force!

[Mary**]

Great job! You are so correct!

[ABQ bloodbanker]

We correlate all of our tests that are performed using different methodology. Blood types, we get one of every ABORH (8 total) and run in tubes and gel, for example. We also correlate the same methodology (Antibody screens, for instance) that we run manually and on the ProVue. And then, we have 3 ProVues, so we correlate all 3 ProVues.

I have attached my parity procedure with a nice form I document all results from all locations/instruments. We do this every 6 months.

Denise

HBB PARITY CHECKS.doc

[Townsend]

I read Suzanne Butch's article last year when the CAP revision came out. When we prepared and went through our CAP mock inspection, I called CAP for explanation to see if this really applied to tube vs gel testing (or other methods). They told me that this is exactly what the checklist item was intending to cover. So whether you're convinced or not (I'm voting no), the inspectors will be looking for this when they come out to your BB next time. We created a very general comparison SOP for our gel and tube (antibody screens and direct coombs) to run every 6 months. We currently do manual gel testing with LISS tube as a backup.

Stephanie Townsend, MT (ASCP)SBB

[Kitty Petershagen]

Could you post the attachment by itself? It wasn't with the procedure. Thanks

[ABQ bloodbanker]

Here is the parity worksheet I use.

parity worksheet.xls

[Keith]

I interpret this checklist only applies to the following tests: Blood group and Rh typing, antibody screen, DAT , phenotyping test between different methodologies and it does not apply to the different tests used for antibody investigation because different situations will dedicate which method to be used. Please comment.

[Keith]

Well done. I totally agreed what Suszane Butch's comment about the methods comparsion especially for antibody identifcation methodologies. I think this checklist will make sense for instruments. In our hospital, we have two instruments (Galileo for routine samples and Echo mainly for stat samples). If one is down, then all samples run in the other one. It is important to ensure that it does not matter which instrument to use, the result is the same. I think the comparsion studies will ensure this.

Edited July 4, 2010 by Keith

[Liz]

I would like to ask about the instrument part of “If the laboratory uses more than one instrument/method to test for a given analyte, are the instruments/methods checked against each other at least twice a year for correlation of results?”

~~~~~~~~~

We validate and check the instruments in the Blood Bank and all is well.

However, when the down-time of a machine is long we have had to use the one at the Serology Section. Now, they do their own validations and cross checks and we are all as one Lab Accredited. Yet, one inspector told me that I should not use any instrument that my section, the Blood Bank, has not validated and cross checked. Is that so?

Thank you

Liz