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
In a recent issue of CCLM, an interesting opinion paper reported on a pilot study of the quality of UK laboratories.
Given 5,812 QC data points on 5 different platforms in 9 different laboratories measured over 6 months, and a quality goal of 7.0% how many of those laboratories do you think achieved 5-Sigma quality?
- 100%
- 75%
- 50%
- 25%
- less than 25%
The answer, after the jump...
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Posted by Sten Westgard, MS
Posted by Sten Westgard, MS
It's almost mandatory that any presentation or report discussing patient safety references the landmark IOM report of 2000: To Err is Human - Building a Safer Health System. The takeaway quote from this report is that US hospitals were causing 44,000 to 98,000 deaths that were otherwise preventable. That is, hospitals were causing tens of thousands of avoidable deaths.
A recent paper has attempted to revise that estimate, focusing on Preventable Adverse Events (PAEs) that contributed to the death of patients. Can you guess how lethal US hospitals are now?
- 4,000 to 10,000 PAEs per year
- 44,000 to 98,0000 PAEs per year
- 100,000 to 200,000 PAEs per year
- 210,000 to 440,000 PAEs per year
The answer, after the jump...
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Posted by Sten Westgard, MS
Posted by Sten Westgard, MS
Anyone heading off to Milan this May?
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Posted by Sten Westgard, MS
More evidence of pre-analytical error rates, this time for the Journal of Clinical Pathology. This is from a study back in 2010, my apologies for only finding it this year:
A Six Sigma approach to the rate and clinical effect of registration error in a laboratory, Naadira Vanker, Johan van Wyk, Annalise E. Zemlin, Rajiv T Erasmus, J Clin Pathol 2010:63:434-437.
In this study, they reviewed 47,543 test request forms from a 3 month period of November 2008 to February 2009. The study was conducted at the "chemical pathology laboratory at Tygerberg Hospital - an academic tertiary hospital in the Western Cape Province of South Africa. The laboratory is a division of the National Health Laboratory Services, which is a network of 265 pathology laboratories in South Africa."
Can you guess how many errors they found? And what was the impact of those errors?
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Posted by Sten Westgard, MS
I recently got a smart question from a concerned laboratory scientist. After reviewing one of the Sigma-metric studies on the website, he noted that while a particular method had a bad Sigma-metric, the main reason was due to the bias. His question was essentially (and I am paraphrasing here), "If the bias component comes from a particular difference between the instrument or kit and a reference system, shouldn't it be excluded from the Sigma-metric calculation?"
The reasoning is that the bias problem could be (1) eliminated through recalibration, (2) it may be a bias against a method that is not a reference method, so the difference might not be "real", or (3) if the reference range is adjusted and the method is used in exclusion, bias doesn't matter anyway.
We've had a lot of discussion about bias in our statistics lately. Is this a case where the Sigma-metric is "skewed"? What's your verdict? A discussion after the jump.
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Posted by Sten Westgard, MS
Posted by Sten Westgard, MS
I just wanted to share some pictures of a trip taken back in late April.
The Asian Society of Continuing Medical Education was kind enough to invite me to present in a workshop titled "Assuring Quality, Standardization, and Efficiency in the Laboratory 2012" In Delhi and Mumbai.
Group picture, Mumbai
More pictures, after the jump.
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Posted by Sten Westgard, MS
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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