I’ve written before that total error means error from any source not just analytical error. Thus, if a clinician makes an incorrect treatment decision because the test result is wrong due to user error, it is little consolation to know that the analytical system was ok.
All of this applies to SMBG (self-monitoring blood glucose) where the treating “clinician” and user are the patient.
A Letter in Clinical Chemistry (subscription required) shows that whereas 9 out 10 glucose meters met performance standards when the tests were performed by expert users, only 6 out of 10 meters met standards when the tests were performed by routine users.
Of interest as well is that the authors cite as performance standards both the ISO 2013 standard and the suggested FDA draft performance standard from 2014.