The Westgard Rules

What's New on Westgard Web: May 2011

Posted by Sten Westgard, MS

WHAT'S THE RIGHT GOAL?

Labs are blessed today with a wealth of quality specifications, from
CLIA, Rilibak, RCPA and of course the Ricos et al biological
database. But all those choices can be overwhelming. Often, we are asked,
"What's the best quality requirement?" or "What's the right quality
requirement for my lab?" Here's a guide to help sort the goals and make the
best choice for your needs.

http://www.westgard.com/right-quality-goal.htm


QC REALITY CHECK, PART 4

Dietmar Stockl, PhD, continues his series on real-world internal QC (IQC)
scenarios. What happens when the laboratory purposely sets the wrong
standard deviation?

http://www.westgard.com/dietmar-qc-4.htm


WE NEED MORE DATA, MORE DATA, AND... MORE DATA

The advice about restaurants has its analog in the laboratory. When trying
to assess method performance and conduct validation, laboratories need to
focus on three things: data, data, and more data.

http://www.westgard.com/need-more-datahtm.htm

Q & A: What is a "control range"?

Posted by Sten Westgard, MS

An interesting question came in through email (we always want to hear from you!):

"1. Can we apply Westgard multirules to hematology control?

2. I read in one paper that the hematology control range is calculated as mean +/- 2.5 SD, is this correct and if not how can I calculate own laboratory hematology control range?"

The answer, after the jump...

Q & A: How do you interpret the 2:2s rule?

Posted by Sten Westgard, MS

We got an excellent question the other day via email:

I have heard the term "Within QC" and "Across QC"
used, but what do these refer to specifically and
where can I find more information about what is
meant by those terms? I was not able to find this
information, but laboratory leadership staff said
that "Within QC" referred to assessing multi-rules
"within QC level and across QC runs", and that
"Across Qc" referred to assessing multi-rules
"looking at both QC levels, can be within same run
or back-to-back runs".

A lab has the following multi-rules; "Within QC"
1:3s, 1 QC result outside 3sd; 2:2s, 2 consecutive
QC results outside 2sd on the same side of the mean;
4s, 2 consecutive Qc results differ by more than
4sd; and 1:2s, 1 Qc result outside 2sd and within 3.
(1:2s is used as a warning rule, the others as
rejection rules). The rules for "Across Qc" are as
follows; 2:2s, 2 consecutive Qc results (1 each
multiple levels) are outside of 2sd; and 4s, 2 Qc
results (one of each multiple levels) are >4sd
apart. These are both rejection rules. These
multi-rules are used to assess all tests in a
chemistry lab; the majority of tests are assessed
with 2 levels of Qc, a few use 3 levels of Qc.

The situation arose where QC results on one day for
a cancer antigen were the following:
Day 1A:
Level 1 -Within 2sd, acceptable
Level 2 -1:2s, run was accepted as only the warning
rule 1:2s was encountered.

The next day the results were as follows:
Day 2A:
Level 1 -1:2s
Level 2 -Within 2sd
Leadership said run should not be accepted,
violating the "across" 2:2s rule.

However, leadership said the inverse situation would
have been acceptable as *consecutive* data points
did not violate the "across" 2:2s rule, i.e.

Day 1B:
Level 1 1:2s
Level 2 within 2sd

Day 2B:
Level 1 within 2sd
Level 2 1:2s

In the A group, because Level 2 is outside of 2s,
and the very next data point (Level 1 from the next
day) is also out 2s, the run is unacceptable and
should be rejected. In Group B, since consecutive
data points are okay the run is acceptable.

Is this a correct approach? Is it correct to reject
group A (Day 1A and 2A) and not reject group B (Day
1B and 2B)? Do these multi-rules as outlined and
implemented detect some unacceptable variation in
group A that does not exist in group B? Thank you
for any clarification.

So what's the answer? Are scenarios A and B fundamentally different? More after the jump.

Westgard on Risk: Berlin IFCC

Posted by Sten Westgard, MS

James O. Westgard, PhD, will present a lecture on May 18th on Risk analysis of the analytical testing process as part of the IFCC EuroMedLab conference in Berlin, Germany.

See the program here.

 

Congrats to Linda Thienpont

Posted by Sten Westgard, MS

Congratulations to Dr. Linda Thienpont, a great friend of the Website and a leading voice on standardizatino. At the IFCC Berline conference, she will be given the Robert Schaffer award for Outstanding Achievements in the Development of Standards:

From the press release:

"IFCC, the leading organization in the field of Clinical Chemistry and Laboratory Medicine worldwide, today announced that Professor Linda THIENPONT, Faculty of Pharmaceutical Sciences, Ghent University, Belgium, is the winner of the 2011 IFCC-Robert Schaffer Award for Outstanding Achievements in the Development of Standards for Use in Laboratory Medicine.

"The 2011 IFCC - Robert Schaffer Award for Outstanding Achievements in the Development of Standards for Use in Laboratory Medicine, co-sponsored by NIST and CLSI, recognizes specifically an individual who has made outstanding and unique contributions to the advancement of reference methods and/or reference materials for laboratory medicine to facilitate improved quality of clinical diagnostics and therapies, which would in turn lead to reduced costs and improved patient care. Linda Thienpont, Professor of Analytical Chemistry and Director of the Analytical Chemistry Reference Laboratory at the University of Ghent in Belgium, has shown exceptional leadership in the development of reference measurement procedures for clinical laboratory testing. She has published over 100 peer reviewed papers in the area of analytical method development and standardization and participated as invited speaker at many major medical and clinical congresses throughout the world. She has a long and distinguished record of developing standard methods and reference materials for use in measuring a large number of analytes, including steroid and thyroid hormones, and a number of other analytes.

"Prof. Chris Lam, Chairman IFCC Awards Committee, said: “We are delighted in electing Professor
Thienpont for the 2011 IFCC - Robert Schaffer Award for Outstanding Achievements in the Development of Standards for Use in Laboratory Medicine. Professor Thienpont has a well established international reputation and archievements as a leading expert in the field of standardization and harmonization. She is an active contributor and pioneer to policies and experimental protocols needed to implement standardization”."

Linda has been a strong voice for quality and accuracy and well-deserves this award.