Accuracy of reagent strips in detecting hypoglycemia in the emergency department.

STUDY OBJECTIVE

Although reagent strips are commonly used, their reliability to estimate blood glucose concentration and guide administration of dextrose solutions in the emergency department environment has not been proved. We determined the accuracy of visually interpreted reagent strips (Chemstrip bG, Boehringer Mannheim Corp, Indianapolis, IN) and their ability to identify hypoglycemic patients in the ED.

METHODS

We conducted a prospective, nonrandomized blinded clinical study of the visual estimation of blood glucose values by ED personnel using Chemstrip bG reagent strips during a 4-month period. Simultaneously obtained blood samples sent for laboratory glucose determination served as controls. The study was conducted at a large university hospital ED with an urban patient population. A convenience sample of 215 adult ED patients underwent serum glucose determination with data form completion. No study intervention was tested, although timing of administration of dextrose solutions, if given, was recorded.

RESULTS

Hypoglycemia was defined as a glucose concentration less than 60 mg/dL on standard laboratory analysis. Reagent strips identified 28 of 29 of these patients (sensitivity=97%), and 171 of 182 patients without hypoglycemia (specificity=94%, negative predictive value=99%) compared with control samples. The 1 false-negative reagent strip reading of 80 mg/dL was obtained from blood stored in a serum separator tube and had a laboratory glucose value of 39 mg/dL. Eighty-seven percent of the reagent strips were within +/-60 mg/dL of the control value for the laboratory glucose reference range less than 350 mg/dL.

CONCLUSION

Visually interpreted Chemstrip bG reagent strips provide an acceptable estimation of blood glucose concentration in the ED and are highly sensitive in detecting hypoglycemia.