Laboratory Quality Control Based on Six Sigma
Collective expert opinion regarding reducing the risk of harm to the patient and QC frequency can be found in:
- Cooper, et al. “Collective opinion paper on findings of the 2010 convocation of experts on laboratory quality”, Clinical Chemistry Laboratory Medicine. 2011; 49(5):793-802.
Over 40 medical laboratory opinion leaders, pathologists, clinical biochemists and physicians gathered together to discuss current challenges for laboratory medicine including determining the appropriate frequency of quality control. They concluded that a risk-based approach to determining QC frequency is useful and suggested using sigma (σ) to divide tests into groups:
- >6σ (excellent tests) – evaluate with one QC per day (alternating levels between days) and a 1:3.5 s rule.
- 4σ–6σ (suited for purpose) – evaluate with two levels of QC per day and the 1:2.5 s rule.
- 3σ–4σ (poor performers) – use a combination of rules with two levels of QC twice per day.
- <3σ (problems) – maximum QC, three levels, three times a day. Consider testing specimens in duplicate.
For more information on sigma (σ) see the related articles Six Sigma Background, Sigma Values in the Laboratory, Sigma Values calculated from the Unity™ Interlaboratory Programand Sigma Values and QC Strategy Design. For more information on including enough levels see the related article Concentrations of Control Materials.