Control De Calidad

|A War of Words in Laboratory Medicine, Part IV: |[pic] |
|A Sentinel Example |A word from |
|A Sentinel Test: HbA1c |Dr. Westgard|
|Current Performance | |
|What is test quality today? |  |
|What quality needs to be assured? ||
|What analytical performance is needed? | |
|Lessons to be learned | |
|References ||
|War of Words, Part I | |
|War of Words, Part II | |
|War of Words, Part III| |


Part III of this series concluded that “if we do not manage quality quantitatively, then we must provide our users and customers with information about the quality being achieved, or the uncertainty of test results. The best approach is to manage quality quantitatively when intended use can be objectively defined and to provide information on uncertainty whenintended use has not been well-defined.”
I have argued that the “Total Error framework” is most useful when laboratories want to manage quality in an objective and quantitative manner. But most laboratories today are not doing that! As evidence, let me share some results from a survey of some 300 laboratories in early 2007 (conducted in collaboration with Bio-Rad):
• From yourexperience, what do you think about the performance of your QC?
• 63% - Provides reliable monitoring of test quality
• 24% - Probably is overly sensitive
• 10% - Often gives false alarms
• 4% - Probably not sensitive enough

• How does your lab select its QC rules?
• 41% - Just use 2 SD for all or most tests• 30% - Professional judgment/experience
• 20% - QC planning tools
• 8% - Peer practice

• When asked to provide the quality requirements for their tests, only 8.6% of laboratories provided quantitative values!

These survey results suggest that (a) most laboratories today do not define the quality needed for the clinical use of the test resultsbeing produced, (b) most laboratories select their QC procedures arbitrarily without any consideration of the quality needed for patient care, and yet (c) most laboratories believe that their QC procedure provide reliable monitoring of that undefined and unknown test quality.
Given this absence of quality management, laboratories need to provide their customers with information about theuncertainty of their measurements. Otherwise, physicians may improperly interpret the significance of a patient test value vs a reference limit, cutoff, or serial changes in that patient.
A Sentinel Test!
The state of analytical quality management today can be illustrated using the glycated hemoglobin (GHb) test, which is one of the most important tests performed by laboratories today because of its...