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Sigma Metric Analysis

Multimode analysis of cobas 6000 in Turkey

Our first analysis of 2024 tackles a cobas 6000 in Turkey. Can the instrument meet CLIA 2024 standards, EFLM minimum, or EFLM desirable performance specifications?

Multimode analysis of cobas 6000 in Turkey

January 2024
Sten Westgard, MS

See the other analyses in this series:

Sigma Metric Score: 3.0 out of 6. Moderate quality. (biological variation goals, EQA comparison over a longer period of time, imprecision over a longer period of time)

This cobas 6000 data comes from Health Science University, Istanbul Basaksehir Cam and Sakura City Hospital:

A comparative analysis of Sigma metrics using conventional and alternative formulas, Kamil Taha Ucar, Abdulkadir Cat, Clinical Chimica ACta 549(2023) 117536 https://doi.org/10.1016/j.cca.2023.117536

"The study utilized data from January 2022 to June 2022, comprising internal quality control (IQC) and external qualit assessment (EQA) data, for SM[Sigma-metric] calculation. The clinical chemistry parameterswere analyzed on a Roche Cobas 6000 c501 auto analyzer using original reagenets from the manufacturer."

The TEa goals applied can be found on our Consolidated Chemistry Performance Specifications page.

 

TEST % Bias CV
Albumin BCG 1.9 2.00
Albumin BCG 1.9 2.50
ALT 1.8 3.40
ALT 1.8 3.20
Amylase 2.1 4.00
Amylase 2.1 4.80
AST 4.4 2.80
AST 4.4 3.30
Bilirubin, Total 1.8 5.60
Bilirubin, Total 1.8 4.30
Cholesterol, total 1.6 4.50
Cholesterol, total 1.6 4.10
Creatinine Kinase (CK) 1.8 2.50
Creatinine Kinase (CK) 1.8 2.40
Creatinine 1.4 2.80
Creatinine 1.4 4.80
Glucose 1.4 2.00
Glucose 1.4 3.60
CRP 1.9 2.40
CRP 1.9 5.20
GGT 2.2 3.60
GGT 2.2 6.30
HDL C 3.0 3.00
HDL C 3.0 5.30
Iron 2.7 3.30
Iron 2.7 3.00
LDH 0.9 4.90
LDH 0.9 3.00
LDL C 1.2 2.10
LDL C 1.2 5.60
Magnesium 2.1 2.50
Magnesium 2.1 3.70
Phosphorous 1.6 2.10
Phosphorous 1.6 2.30
Triglycerides 1.7 1.40
Triglycerides 1.7 2.40
Protein, Total 1.4 2.90
Protein, Total 1.4 3.70
Urea Nitrogen 2.8 2.50
Urea Nitrogen 2.8 3.70

 

Sigma-metrics according to EFLM-derived DESIRABLE performance specifications

 

Let's get the worst case out of the way. Over half of the performance is below 3 Sigma. It's clear the EFLM desirable specifications, which used to be the de facto global standard, may not be realistically achievable.

No wonder EFLM database officially recommends using the minimum performance specifications, not the desirable. So how does that look?

Sigma-metrics according to EFLM biological variation MINIMUM performance specifications

2024 multimode cobas 6000 Turkey NMEDX2


It's a big improvement, now only just under a third of the performance is below 3 Sigma. Over 40% is now in the Six Sigma bull's-eye..

Here's one of the most interesting new aspects of CLIA's new 2024 goals. Are they more or less demanding than EFLM goals?

Sigma-metrics according to CLIA 2024 performance specifications

2024 multimode cobas 6000 Turkey NMEDX3
 

The CLIA 2024 goals cast a favorable light on the Dymind D7, with only 40% of the performance at 6 Sigma, and just over 25%s at 3 Sigma or below. MCV and Platelets are in the Bull's-eye, as well as one level of WBC performance.

Just for a complete look, let's see how the oldest goals would have graded the Dymind D7.

Sigma-metrics according to CLIA 1992 performance specifications

2023 Dymind D7 Croatia CLIA92 NMEDx

If we apply the CLIA 2024 goals, over 25% of the performance is still below 3 Sigma. So that's better than the EFLM assessments. But notice that only 12.5% of the performance is in the 6 Sigma zone. So the EFLM minimum standards are in some way easier to achieve than CLIA 2024 goals.

Conclusion

As a global leading diagnostic platform, we expect more from the cobas 6000. But this installation in Turkey found it difficult to achieve any of the three of the performance standard sets. This could be a local issue, or it could point to greater problems in the platform. As always, more data is better.