18 appendix b: specifications, Determination of alarm performance, Con’t) – Abbott Freestyle PRT03831-xxx User Manual
Page 170
18 Appendix B: Specifications
(con’t)
Determination of Alarm Performance
The threshold alarm is characterized below. The projected alarm performance has not been established.
The performance of low and high glucose alarms was assessed in an in-clinic study using 58 subjects with
type 1 diabetes wearing one FreeStyle Navigator sensor on the arm and one sensor on the abdomen. FreeStyle
Navigator continuous data were masked from the subjects and investigators and the alarms were not turned
on. During 50 hours the subjects’ venous glucose was tested with a YSI 2300 Stat Plus glucose analyzer at 15
minute intervals. Arm and abdomen data were pooled in the alarm analysis. Alarm performance was evaluated
in a retrospective analysis of the study data. As alarm performance was developed retrospectively, your results
may vary from those reported below.
Definitions:
Hypoglycemic event – two or more successive YSI measurements below the alarm threshold or one YSI
measurement 6 mg/dL below the alarm threshold.
Hyperglycemic event – two or more successive YSI measurements above the alarm threshold or one YSI
measurement 6% above the alarm threshold.
True Threshold Alarm – a threshold alarm that occurred ± 30 minutes from the start of a hypoglycemic or
hyperglycemic event
True Alarm Rate – the percentage of time the glucose level was beyond the threshold and an alarm was
activated
Events Detected by True Threshold Alarms
Total Events
X 100
Missed Alarm Rate – the percentage of time the glucose level was beyond the threshold and an alarm was not
activated
Events Not Detected by True Threshold Alarms
Total Events
X 100
False Threshold Alarm – a threshold alarm that occurred when a YSI measurement within ± 30 minutes was
not beyond the threshold setting
False Alarm Rate – the percentage of time an alarm occurred when glucose level was not beyond the threshold
setting
False Threshold Alarms
Total Threshold Alarms
X 100
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Section 18
Appendix B: Specifications