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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Posted by Sten Westgard, MS
In the December 2011 issue of Point of Care journal, an interesting study was published:
Preanalytical Errors in Point-of-Care Testing: Auditing Error of Patient Identification in the Use of Blood Gas Analyzers, Natalie A Smith, David G Housley, Danielle B. Freedman, Point of Care, Volume 10: Number 4, December 2011.
The study looked at patient identification errors on a blood gas analyzer in various departments in a hospital. Bearing in mind that this is just one type of pre-analytical error, what do you think the rate was? Given around 100,000 tests, what would you guess as the number of defects?
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Posted by Sten Westgard, MS
Posted by Sten Westgard, MS
Posted by Sten Westgard, MS
One more shot at error rates! At the IFCC Berlin conference, there was an intriguing abstract about the use of Quality Design/Planning tools in the laboratory:
Abstract #1062: Efficiency of Analytical Qualit yControl with Various Quality Planning Tools in Thai Clinical Laboratory. K. Sirisali, S. Manochiopinj, S. Sirisali.
How high do you think out-of-control rates can go?
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Posted by Sten Westgard, MS
Earlier we discussed error rate issues at the Point-of-Care. But we didn't want to leave the "regular" laboratory out of the fun, so here's a study of error rates that came out in 2010:
Evaluation of errors in a clinical laboratory: a one-year experience, Goswami B, Singh B, Chawla R, Mallika V, CCLM 2010;48(1):63-66.
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A new study in Clinical Chemistry investigated the errors rates for Point-of-Care (POC) devices:
Can you guess what the error rates were?
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Posted by Sten Westgard, MS
[This picture is actually from Curitiba, Brazil, the SBAC conference back in late June, at a lecture I gave there on Sigma-metrics. I don't have a picture of my lecture from Atlanta, but there is video.]
I gave a short booth presentation on Best Practices for Sigma-metrics at the Abbott Diagnostics booth during the AACC/ASCLS convention. This is now available online for those interested.
The link, after the jump.
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Posted by Sten Westgard, MS
It's that time of year again, where the usual and not-so-usual suspects of the laboratory world gather and discuss science - mixed in with a healthy dose of commerce. We have just returned (and are still recovering from) the annual AACC/ASCLS meeting in Atlanta, Georgia.
James O. Westgard at the Westgard QC booth for the 2011 AACC/ASCLS exhibition
More pictures and details of the convention after the jump...
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