Comparison of glucose point-of-care values with laboratory values in critically ill patients.
BACKGROUND
Blood from central venous or arterial catheters as well as from fingersticks is often used for point-of-care glucose testing.


OBJECTIVE
To compare glucose values obtained with a point-of-care device for catheter and fingerstick blood samples with values obtained by clinical laboratory analysis of a catheter blood sample.


METHODS
A method-comparison design was used. Point-of-care values for fingerstick and catheter blood samples were compared with laboratory values for blood from catheters in a convenience sample of 63 critically ill patients. Device bias and precision were calculated and graphed according to the Bland-Altman method, and a t test was used to determine differences in glucose values for the 2 methods.


RESULTS
Laboratory glucose values for blood from a catheter sample differed significantly from point-of-care values for blood from a fingerstick (t(1,61) = 5.01; P < .001) and from a catheter (t(1,61) = 3.91; P < .001). Bias and precision for the point-of-care device was large (fingerstick, 8.7 and 13.7; catheter, 7.0 and 14.0); 20% of the values differed from the laboratory glucose values by more than 20 mg/dL. Point-of-care glucose values for fingerstick and catheter samples did not differ (P = .41).


CONCLUSIONS
Glucose values obtained with a point-of-care device differ significantly from those obtained by laboratory analysis. The magnitude of these differences calls into question the widespread practice of using point-of-care glucose testing to guide insulin titration for tight glucose control. Errors in dosing could easily be made because of the large bias and precision associated with a point-of-care device.
Providence St Vincent's Medical Center, Portland, Oregon, USA. Anna.Shearer@providence.org
Anna
A
Shearer
Marilyn
M
Boehmer
Melanie
M
Closs
Rosalina
R
Dela Rosa
Jean
J
Hamilton
Karen
K
Horton
Rose
R
McGrath
Christine
C
Schulman
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001786:Blood Glucose / Q000032:analysis*; D002404:Catheterization; D003422:Critical Care; D003955:Diagnostic Tests, Routine / Q000295:instrumentation / Q000592:standards*; D006788:Hospitals, Voluntary; D006801:Humans; D007362:Intensive Care Units; D008875:Middle Aged; D009922:Oregon; D019095:Point-of-Care Systems / Q000592:standards*; D015203:Reproducibility of Results; D055815:Young Adult
D001786:Blood Glucose