How Calibration Precision checks are implemented in medical device companies

[Hamaltonian]

Hi all,

As you may be aware, CFR Title 21 820.72.b states that "Calibration procedures shall include specific directions and limits for accuracy and precision."

I understand how accuracy is checked, i.e. comparison to a known standard value, I also understand the meaning of precision but my question is- How do you implement precision checks into a calibration procedure? What is common practice in industry to ensure CFR Title 21 820.72.b is adheared to (with regard to precision limits)?
i.e How does precision fit into calibration activities?

Thanks for your help in advance,
H

 

[Stijloor]

A Quick Bump!

Can someone help?

Thank you very much!

 

[dwperron]

Another interesting subject.

"Specific directions and limits for accuracy" is typically the manufacturer's tolerance. This is because, minus any other guidance, it is assumed that the instrument performance will be within manufacturer specifications. It does happen that limits for accuracy can be determined for the application requirements that the instrument is measuring, and those can be used in the calibration procedure (for example, you only need to know the refrigerator temperature to within ±5°F, not the accuracy of the monitoring device). In most cases the specifications are what determines "accuracy".

How about "precision"? The easy way to determine precision is to analyze a set of multiple measurements. But what do you do about the specific limits for precision? Most instruments do not have specifications for precision (or repeatability), so the manufacturer does not supply guidance. Again, you can derive your own based on your determined measurement requirements.

In most cases, when there is no guidance concerning "precision" requirements, you can make a series of measurements instead of a single measurement, using the manufacturer tolerance as the limit for both accuracy and precision. How many measurements? I'm afraid there is no guidance there, I've seen 3, 5, and 10 measurements used. The requirement is to have a procedure that tells you how many measurements to take and what the limits are on the measurements.

Also, it wouldn't hurt to get guidance from your auditor, if possible.