This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: ECG and Arrhythmias 1, Subject name: Medicine
An 80-year-old person has developed a PCA territory stroke. On ambulatory Holter he is found to be having atrial fibrillation. What calculation should be used to evaluate for renal insufficiency of the patient? 
Select and explain. 
A. NIHSS score, B. ABCD2 score, C. CHADS2- VaSc score, D. Cockroft Gault formula
D: Cockroft Gault formula
Answer: D: Cockroft Gault formula 
Explanation: Option A: NIHSS Score- evaluation of stroke in a patient. Option B: ABCD2 score- Used in patient who have risk of stroke = In TIA Option C: There is always risk of embolic stroke in A. fibrillation so we prescribe anticoagulants to patient on the basis of CHADS2- VaSc score we make decision of Anticoagulation. Option D: Cockcroft Gault formula