Tips for Successful Proficiency Testing

 Everyone wants their proficiency testing (PT) program to be successful. They also want to conduct PT in the most efficient way possible without interfering with patient testing. Following some practical tips can go a long way toward making your proficiency testing process run smoothly. Toward that end, we explored best practices for proficiency testing by interviewing an experienced technical consultant, Elizabeth Staubs, who has consulted with POLs for many years. She provided tips during our interview that are applicable to all laboratories, large or small. The following are excerpts from our interview.

How should I select a PT provider?

When I came on board in a physician’s office about twenty years ago, there were only one or two PT providers. Today more PT providers are available to you and they offer a wider range of options and services.  To make an informed choice, conduct thorough research of available providers by:

Comparing the analytes and modules they offer to your test menu 

Comparing the cost, and the scope and level of service of each provider  

Determining if there is a peer group for your instruments and methods 

Do you have suggestions for what to do when the samples arrive? 

Open the box right away and check the instructions to determine the proper storage conditions until you can perform the testing. Make sure all the samples are intact and the package includes everything you ordered. Contact your PT provider immediately if a container is broken, a sample has leaked, or a sample is missing. Immediate proper storage is essential to avoid sample deterioration, which may yield poor test results.

It is difficult for me to fit PT into my workload. How can I make sure I complete proficiency testing by the deadline? 

Remember that you must return the results to the PT provider by the date indicated on the form (usually within 10 working days of receipt of the samples.) Post a note in the lab to remind you when the results are due.

You should integrate testing the PT samples into your normal workload. In most cases, you are performing PT for tests that you perform regularly anyway. Let’s say you run glucose tests every day but you only run cholesterols twice a week. You can run the PT samples for glucose on any day, and can select the day based on your workload. Same for the cholesterol PT samples- select a day when you would normally be running cholesterols to run your PT. Of course, if by some chance you did not have any patient cholesterol testing to perform before the PT results are due, you would still need to run the PT samples within the specified timeframe.

Who performs the proficiency testing in your lab? 

I recognize that it is important for all personnel who perform patient testing to rotate performing the PT. In fact, performing the PT and getting successful results is part of our employee competency assessment.

The Hematology PT module my lab receives includes samples for CBCs, coagulation, and blood cell identification. The three people who run these tests take turns running the PT specimens. Our lab receives three shipments per year, so each of us performs one event per year.

Physicians, lab directors, and lab managers who perform patient testing should also rotate performing PT. This is a way to demonstrate competency for running the tests they perform.

The lab director in my office is a hematologist who performs the blood cell IDs and manual cell counts when a staff member is on vacation or when our office is especially busy. He makes a point to participate in PT for these tests and I think it sets a good example.

Do you need to participate in PT for unregulated analytes? 

Although labs are not required to enroll in proficiency testing for unregulated analytes, you are required to demonstrate the accuracy of those test results in some other way, such as split sample testing twice a year. 

Reticulocyte counts are an example of an unregulated analyte that we perform. If I sent the five samples to my contracted reference lab for split sample testing, I would have to pay them to perform those tests just as I would for other send-out tests. 

Here’s a cost savings tip. Rather than using a reference lab, I send the samples to a local hospital for testing. A comparison of my results and the split sampling results is an appropriate measure of testing accuracy. 

6. How do you review your PT scores when you receive them?

First, I make sure that I received a score for all the results I submitted. Then I review the mean and standard deviation of each analyte and compare where I stand in relation to the peer groups. This allows me to identify a shift in my data that my quality control testing may not have discovered. In other words, even when my results pass, I always look for variances like all the results for a particular analyte being below the mean. This could indicate a trend that I want to look into to prevent a future PT failure and to make sure my patient results aren’t trending.

If my review reveals that the results are within the acceptable range, with no apparent problems, I write “no deficiencies, no corrective action necessary” on the cover page, then sign and date it. If any analyte fails, I conduct a thorough investigation into the problem, including checking QC, maintenance, and calibration for the instrument. If indicated, I re-evaluate my patient results for the analyte. After I document my review, I have the lab director sign and date the PT scores and we discuss any issues. I also have the lab director sign and date any corrective action.

7. What are some tips for documenting PT?

Craft your own PT checklist that reflects every step in the process. Everyone who performs proficiency testing should use the checklist throughout the PT process to document all PT activities. 

Photocopy your PT results before submission, if you mail them in, and retain all PT documentation for at least two years. Instrument tapes can deteriorate quickly so be sure to photocopy them so they will be preserved. 

8. How do you prefer to submit your results, online or by fax?

I generally submit my results by fax. Because I record my results as I perform the tests, I can fax my results as soon as I complete testing and perform a clerical check. When I fax my results I receive a fax confirmation sheet that documents the exact date and time I submitted the form. 

If I submitted my results online, I would have to reenter my data on the online submittal form, which involves an extra step. I also have to remember to print a copy of the online submittal form for my records before I click the Submit button.

9. Do you have any interesting PT stories for us?

Yes, here’s an interesting experience that demonstrates the value of PT. My PT scores for our dry-slide chemistry analyzer were fine but my quality control results were consistently at the low end of the range. 

My first step was to do split sampling with the reference lab, which confirmed that my patient results were fine. I had the analyzer serviced, and I calibrated a number of times to see if my results would change. Nothing changed. Continuing to investigate, we found that two particular lot numbers of slides yielded the same low results for QC. 

When I switched to another lot number of slides and reran the QC, the results were within acceptable range. I concluded that the analyzer was working properly, as indicated by my successful PT, but a matrix effect between the control material and those particular lots of the slides resulted in my low QC results. Matrix effect is interference, usually caused by the non-human components of the sample that affect the analytical method’s ability to accurately measure the analyte.

Although it took about three months of investigation and documentation, it was well worth the time and effort to prove that my patient results and PT results were accurate.

10. Any last words of advice for the labs out there?

Proficiency testing is more than a way to meet a regulatory requirement. PT is a powerful tool to confirm the accuracy of your testing. That’s why it’s so important to run your PT the same way you run your patient samples- so it’s a true reflection of your everyday performance. It’s great when we get our scores back and we got 100%. It gives us confidence knowing our patient results and the service we provide are on track.

You can also use the PT results to find problems with your instruments. PT serves as an indispensable quality measure and can indicate problems in your patient testing that quality control did not reveal. 

I also use proficiency testing results as a valuable tool when performing competency evaluations. It’s an objective measure of patient testing performance for anyone who performs testing. 

As far as advice, the most common problem associated with PT performance is clerical errors, so always double check your entries! Be careful to select the correct instrument/method code and watch those decimal points. It is also important to save left over PT samples whenever you can so you can use them later for troubleshooting and other purposes, such as calibration verification.

Elizabeth Staubs, MT(ASCP)SH, is President of Tri-State Laboratory Consulting, LCC in Inwood, WV. Ms. Staubs has been advising physician office laboratories since 1992 in laboratory start-up activities, CLIA and OSHA compliance regulations, and general laboratory operations. Additionally, she is a presenter at the COLA Symposium for Clinical Laboratories, teaching labs about POL consulting and documentation and record keeping. Elizabeth is laboratory manager for the high complexity laboratory in a hematology/oncology/internal medicine practice.