Diagnostic accuracy of point-of-care testing for diabetic ketoacidosis at emergency-department triage: {beta}-hydroxybutyrate versus the urine dipstick.

OBJECTIVE: In the emergency department, hyperglycemic patients are screened for diabetic ketoacidosis (DKA) via a urine dipstick. In this prospective study, we compared the test characteristics of point-of-care β-hydroxybutyrate (β-OHB) analysis with the urine dipstick.

RESEARCH DESIGN AND METHODS: Emergency-department patients with blood glucose ≥250 mg/dL had urine dipstick, chemistry panel, venous blood gas, and capillary β-OHB measurements. DKA was diagnosed according to American Diabetes Association criteria.

RESULTS: Of 516 hyperglycemic subjects, 54 had DKA. The urine dipstick had a sensitivity of 98.1% (95% CI 90.1-100), a specificity of 35.1% (30.7-39.6), a positive predictive value of 15% (11.5-19.2), and a negative predictive value of 99.4% (96.6-100) for DKA. Using the manufacturer-suggested cutoff of >1.5 mmol/L, β-OHB had a sensitivity of 98.1% (90.1-100), a specificity of 78.6% (74.5-82.2), a positive predictive value of 34.9% (27.3-43), and a negative predictive value of 99.7% (98.5-100) for DKA.

CONCLUSIONS: Point-of-care β-OHB and the urine dipstick are equally sensitive for detecting DKA (98.1%). However, β-OHB is more specific (78.6 vs. 35.1%), offering the potential to significantly reduce unnecessary DKA work-ups among hyperglycemic patients in the emergency department.