Past Events
We will be at the AACC Anaheim 2023
Booth Number 4576
Conveniently located in Hall A near the Posters
Take the QC Quiz and win a GATOR!
Poster Display Date/Time: Wednesday Jul 26, 2023 9:30 AM - 5:00 PM U.S. Pacific Time Hall A Presentation Time – Discuss posters, quality and risk with Zoe Brooks: 1:30 - 2:30 PM U.S. Pacific Time
Impact of Seven Incremental Scenarios of QC Strategies
Abstract Number: 820
Poster Number: B-156
Metrics to express risk in terms of:
A. risk sources,
B. potential events,
C. their consequences and
D. their likelihood
- as recommended by ISO 31000
Abstract Number: 975
Poster Number: B-157
Sigma Metric Equation Proposed by James O. Westgard is Wrong
Abstract Number: 463
Poster Number: B-155
Please send questions in advance or book an appointment to discuss posters, risk and software with Zoe:
Impact of Seven Incremental Scenarios
of QC Strategies
Background
Background
CLSI EP23A states that “At the least, the ability of the QC procedures to detect medically allowable error should be evaluated.” It also defines that “The QC strategy using QC samples should include the following for each measuring system:
•The type and number of QC samples tested per test event
•The statistical QC limits used to evaluate the results
•The frequency of QC sample test events
•The frequency of periodic review
•The actions taken when results exceed acceptable limits”
Methods
The number of results reported before the first QC flag after a simulated shift to a 5% error was calculated using CatalystQC software for seven incremental scenarios of quality control beginning with [A] Original QC rules (1-3s/2-2s), chart limits, frequency (once per day), analytical bias & SD; [B] Westgard Rules based on sigma values; [C] Westgard QC frequency; [D] Chart means & SDs set to measured values; [E] Improved bias and/or SD where advised by CatalystQC software; [F] Single CatalystQC rules; [G] QC bracketed at the end of each day.
Conclusion:
Selecting Westgard rules and frequency alone will not reduce patient risk significantly. Assigning QC chart values to recent mean and SD and improving analytical bias and SD have the most impact on reduction of patient risk. CatalystQC single rules are more effective than Westgard rules. Bracketing QC with verified-effective QC will reduce patient risk to zero.
Metrics to express risk in terms of A. risk sources, B. potential events, C. their consequences and D. their likelihood - as recommended by ISO 31000
Background:
ISO 31000 Risk Management Guidelines provides guidelines on managing risk faced by all organizations. “Risk is usually expressed in terms of A. risk sources, B. potential events, C. their consequences, and D. their likelihood.” I compared risk metrics to implement these guidelines in medical laboratories to sigma metrics to examine the most effective way to enable risk evaluation as ‘the process of comparing the estimated risk against given risk criteria to determine the acceptability of the risk’ (CLSI EP 23A.)
Conclusion:
There is a good relationship between sigma and projected failures per year.
Sigma is NOT a good indicator of cost of error per year, or the number or cost of failures reported after a simulated failure.
Sigma Metric Equation Proposed by James O. Westgard is Wrong - as recommended by ISO 31000
Background
2022 AACC Poster #132 of the same title described how the Westgard sigma metric equation of [A] SM = (TEa – Bias)/SD proposed by James O. Westgard is NOT wrong when compared to the industrial practice of calculating sigma as [B] the difference between the mean and nearest upper or lower tolerance limit divided by the SD. Formulae [A] and [C] produce the same results. The often-recommended practice of calculating sigma as [C] Sigma = (%TE -|%Bias|)/CV%, however, produces results that differ from either formulae described above whenever bias is not zero. This formula [C] using percentages is