Maiwall et al reported a renal dysfunction index (RDI) for evaluating a hospitalized patient with cirrhosis. Hyperkalemia and renal failure has prognostic significance for these patients. The authors are from the Institute of Liver and Biliary Sciences in New Delhi.
Patient selection: hospitalized for cirrhosis
Outcome: 90-day mortality
Parameters:
(1) serum BUN in mg/dL (referred to as "blood urea" in text)
(2) serum creatinine in mg/dL
(3) serum sodium in mmol/L
(4) serum potassium in mmol/L
renal dysfunction index = RDI =
= (3 * LN(1+(BUN))) + (6 * LN(1+(creatinine))) + (0.2 * (urea) / (creatinine)) = (0.5 * (sodium)) + (0.2 * (potassium)) + 65
where:
• 1 is added in the log transformation to avoid LN(0) if BUN or creatinine is 0.
• The paper uses a log transformation but does not specify LOG10 or LN. LN used.
Interpretation:
• The higher the RDI the worse the 90-day survival.
• According to Figure 3 the 90-day survival is about 95% up until an RDI of 19, then declines to 25% at an RDI of 50.
Performance:
• The area under the ROC curve is 0.71-0.72.
