1. Serum creatinine >1.5 mg/dl and/or calculated creatinine clearance < 55 ml/min using the Cockcroft-Gault Creatinine Clearance formula (CrCl). CrCl = {(140-Age) x Weight (kgs) x 0.85 (if female)}/ {72x Serum Creatinine (mg/dl)}