After premiering this event at ADLM, we are opening it up to everyone through zoom. Please join us September 25th, at 11 am central standard time. At last, a frank look at why we need to do less QC, and how we can make those reductions safely. If you enjoy being out of control every day, if you get a thrill every time you have to repeat a con...
Posted by Sten Westgard, MS
Posted by Sten Westgard, MS
While traveling in the middle east recently, I was asked by a colleague about the new US IQCP regulations, specifically how to implement them in their foreign laboratory.
Frankly, I was a bit shocked. I didn't realize that anyone outside the US was paying attention to the IQCP roll-out.
But it does raise a good question: Is IQCP a global necessity? Or merely a US idiosyncrasy?
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Posted by Sten Westgard, MS
A recent question came in from a technical support consultant for a major diagnostic manufacturer:
"It is for Free T4 analyte. Customer [has] establihed a QC range after 20 QC runs. Mean and SD were derived from 20 runs and %CV achieved from 20 runs is 1.2%. Allowable interassay precision criteria according to CLIA is 6%.
"Now when customer [applies] Mean and SD according to the established range many...times they face QC rules violations of 41s and 10x.
"So can you please suggest, when the SD is too narrow is it necessary to apply these two rules to immunoassays?"
What's your guess? I'll take a stab at an answer, after the jump.
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Posted by Sten Westgard, MS
I came across a very valuable paper in Clinica Chimica Acta on the stability of hematology controls for MCV. (Some of you are already guessing what this is going to be about...)
If you take a hematology control, how many SDs should you expect to see it shift at week 5 of use versus the first week of use? In other words, what is the SDI you should expect?
- 1 SDI
- 2 SDI
- 3 SDI
- 4 SDI
- 5 SDI
- higher than 5 SDI
The answer, after the jump...
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Posted by Sten Westgard, MS
Posted by Sten Westgard, MS
As many of you know, the FDA has issued new draft guidelines about Blood Glucose Monitoring Test Systems for Industry and Manufacturers.
Recently, the AACC held an excellent webinar where an Dr. Courtney Lias, PhD from the FDA discussed the intentions of the new guidances and then fielded a LOT of questions. I don't want to step on what Dr. Lias and the AACC accomplished during their webinar. There was useful information in that presentation and I encourage others to consider getting those materials once they become available on the AACC website.
However, while reading through the guidances and talking to laboratories these past few months, I thought I might share a few observations...
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Posted by Sten Westgard, MLO
In the November 2012 MLO magazine there is an intriguing article by Roy Midyett, a hematology supervisor, titled "Empty QC"
Here's how Mr. Midyett defines "Empty QC":
"Empty QC is any nominal QC that does not give techs performing the test any more confidence than they would have without the QC, and has by logic or experience, no influence on the reporting of the test."
Is Mr. Midyett correct? Have our QC procedures become meaningless gestures? More after the jump.
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Posted by Sten Westgard, MS
So here's a Normalized Method Decision chart for a cholesterol method.
Which method would you choose?
Posted by Sten Westgard, MS
Here's a range of statistics describing the performance of a glucose method. Try to pick: Which one has acceptable performance?
- method with combined uncertainty 3.69%
- method with combined uncertainty 6.79%
- method with expanded uncertainty 7.38%
- method with expanded uncertainty 13.58%
- method with 3.78 Sigma
Which method would you pick?
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Posted by Sten Westgard, MS
In the recent issue of Clinical Chemistry, an editorial reviews the current state of Vitamin D testing: "There is common agreement that 25-OHD is a 'difficult' analyte."
25-Hydroxyvitamin D: A Difficult Analyte, Graham D. Carter, Clin Chem 58:3; 486-488 (2012).
At the same time, the editorial notes that marked process is being made:
"Nevertheless, results submitted to the international Vitamin D External Quality Assessment (DEQAS) have shown a gradual reduction in interlaboratory imprecision (CV) in recent years - from >30% in 1995 to 15% in 2011."
The question is, is that reduction in imprecision good enough? Or is the quality required by Vitamin D still too "difficult"?
More after the jump...
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Posted by Sten Westgard, MS
Here's a question that came in about setting the control limits (or range) for a test:
"for some assays we're using this formula: actual SD * 3 and then divided by 2 plus or minus the mean is this acceptable or not because when we use that give us abit wider range than using the mean plus minus 2SD."
When we asked for an example, we got this data:
Manufacturer Data: SD = 22.5, Mean = 224
Actual Data: SD = 8.79, Mean = 223
"We're multiplying ourSD (8.79) by 3 and then we divide it by 2 to give us the new SD which is 13 (8.79*3/2 = 13).
Then we multiply this new SD 13 by 2 to give us the real 2 SD range which is 26.
So our range is now 197 - 249.
Are we following the right way or not?"
The answer, after the jump...
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From Dr. Carmen Ricos, on behalf o the SEQC-Analytical Quality Commission: