Patient selection: hospital inpatient >= 65 years of age
Parameters:
(1) blood urea in mmol/L or blood urea nitrogen in mg/dL
(2) serum creatinine in µmol/L or mg/dL
(3) Barthel index (from 0 to 100)
DPS using SI units =
= (1370 * (UN in mmol/L) / (creatinine in µmol/L)) – (4 * (Barthel index))
DPS using US conventional units =
= (5 * (BUN in mg/dL) / (creatinine in mg/dL)) – (3 * (Barthel index))
Interpretation:
• The cutoff for the SI unit formula was > -240.
• The cutoff for the US conventional unit formula was > -160.
• A value above the cutoff was associated with increased risk of delirium.
• The cutoff is reached with a normal BUN when the Barthel index is 90. A BUN greater than 33 mg/dL is another trigger.
Performance:
• The area under the ROC curve was 0.86 in the derivation cohort and 0.78 in the validation cohort.
