Factors associated with a poor prognosis for a renal allograft:
(1) a change in 1/Cr (delta 1/Cr) < -40% (relative risk 5.9)
(2) estimated creatinine clearance using the Cockcroft-Gault equation < 45 mL/min (relative risk 3.5)
The equation for delta 1/Cr is:
change in 1/Cr =
= ((1/ (followup serum creatinine)) - (1 / (previous serum creatinine))) / (1 / (previous serum creatinine))
This can be rearranged to
change in 1/Cr in percent =
= ((previous serum creatinine) - (followup serum creatinine)) / (previous serum creatinine) * 100%
Limitations:
• Variables for the Cockcroft-Gault equation (use of ideal vs actual body weight, adjustment to 1.73 meter square BSA) were not specified. For the implementation I have used both use of ideal body weight and adjustment to 1.73 square meter BSA.
• A change in 1/Cr < -30% had a relative risk close to 5.