Parameters associated with probability of discharge from hospital:
(1) prothrombin time
(2) serum creatinine
(3) presence or absence of encephalopathy
log ((probability of discharge) / (1 - (probability of discharge))) =
= X =
= 100 - (4.3 * (prothrombin time ratio)) - (0.03 * (serum creatinine in mg/dL) * 88.4) - (0.85 * (-1 if encephalopathy is absent, +1 if present))
where:
• prothrombin ratio = (patient's prothrombin time in seconds) / (mean prothrombin time for normal plasma)
• 88.4 is conversion for creatinine in mg/dL to SI units
The base of the logarithm is not given. Since the usual format for a logit expression uses the natural logarithm, this will be used as the preferred expression.
If the expression is rearranged, it becomes:
probability of discharge =
= (EXP (X)) / (1 + (EXP (X)))
Performance:
• The equation predicted outcome in 90% of admissions.
