Posted by Sten Westgard, MS
What's in a Sigma-metric of 3, 6, or even 11?
Sigma-metrics provide a useful way of classifying method performance and relating that performance to the QC that is necessary to “verify the attainment of the intended quality of test results,” which is a requirement of ISO 15189. But, Sigma-metrics are not foolproof. Does that bother you?
Maybe it's better if we frame this by referencing the 1984 cult film, This is Spinal Tap.
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Posted by Sten Westgard, MS
A recent abstract from the 2009 IFCC/EFCC (Euromedlab) caught my eye:
Quality Indicators for Laboratory Process; assessment in the Trento Department of Laboratory Medicine.
I Caola, C Pellegrini, N Bergamo, E Saurini, P Caciagli.
CCLM 2009
Examining the quality records of five laboratories, they applied a set of Quality Indicators from the IFCC. Errors were tracked and tabulated. The results are quite interesting.
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New Download: Sigma-Metrics Tool (and audioconference presentation)
On September 4th, 2008, Dr. Westgard spoke as part of the AACC audioconference on "New Directions in Laboratory QC" - which was subsequently quoted in the Clin Lab News article on Risk and CLIA. We are pleased to make available Dr. Westgard's complete presentation, as well as two Sigma-metrics Charts and instructions on how to use them in QC Design.
Westgard Sigma Analysis: A new direct HbA1c Method
At the 2008 AACC/ASCLS convention, a poster was presented for a new direct enzymatic assay for %HbA1c. How does it stack up against HPLC and immunoassay methods? How do you judge a method when you've got multiple comparison methods and multiple quality requirements?
Interview: Dr. R. Neill Carey (A brief introduction to EP 15)
We were fortunate to get R. Neill Carey, PhD, the chair of the CLSI EP 15 committee, to present and
explain that new standard at the Chicago Method Validation workshop. He also contributed a chapter to the new Basic Method Validation manual on the same topic. But for those who have never heard of EP 15 before, we conducted a short interview with Dr. Carey. This short introduction to EP 15 may pique your interest in this new guideline.
Thinking about Three Sigma: 2 thoughts on troublesome performance
In a previous lesson, we discussed some possible actions to take when the Sigma-metric for a method is higher than Six. But what about those methods with low Sigma-metrics? What do you do when Sigma analysis delivers bad news?
Posted by Sten Westgard
One of the highlights for me of the AACC convention in Washington, DC, was my inclusion in a poster that analyzed the method performance of the Abbott Architect c8000. I'm pictured here with fellow authors (left to right) Gene Osikowicz, Charles Wilson, and John Baker (lead author). They deserve most of the credit for the work of collecting the data.
The poster can be viewed here and the QC application on Westgard Web can be viewed here. -----
Posted by Sten Westgard, MS
Posted by Sten Westgard, MS
Posted by Sten Westgard, MS
We got the following question emailed to the website recently:
Greetings, I was [wondering] if the following case represents [violation] of 4 1s rule?
Control (A) point 1= EXCEEDS 2 SD /-2 SD lines >> warning
Control (A) point 2= WITHIN 2 SD/-2 SD lines >> accepted
Control (A) point 3= EXCEEDS 2 SD /-2 SD lines >> warning
Control (A) point 4= WITHIN 2 SD/-2 SD lines >> rejection
all the point[s] on the same side of the mean.
What do you think? The answer, after the jump
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Posted by Sten Westgard, MS
Posted by Sten Westgard, MS
Posted by Sten Westgard, MS
Posted by Sten Westgard, MS
Posted by Sten Westgard, MS
Posted by Sten Westgard, MS
A recent op-ed in the New York Times by Dr. Robert Wachter as well as an interview with Don Berwick in HealthLeaders Media broached a taboo topic: is healthcare measuring too much?
'[T]he measurement fad has spun out of control. There are so many different hospital ratings that more than 1,600 medical centers can now lay claim to being included on a “top 100,” “honor roll,” grade “A” or “best” hospitals list. Burnout rates for doctors top 50 percent, far higher than other professions. A 2013 study found that the electronic health record was a dominant culprit. Another 2013 study found that emergency room doctors clicked a mouse 4,000 times during a 10-hour shift. The computer systems have become the dark force behind quality measures.'
How Measurement Fails Doctors and Teachers, New York Times, January 16, 2016
As the global debate over establishing the best error models and performance specifications rages, laboratories are probably asking themselves the same questions that the doctors are asking: how many metrics are too much?
A possible answer, or at least some more questions, after the jump...
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Posted by Sten Westgard, MS