You are seeing a 76-year-old woman in preop clinic prior to sigmoidectomy for recurrent diverticulitis. She has been feeling fine with no symptoms and a good functional capacity. Her history is otherwise significant only for HTN and smoking (quit 2 months ago). Exam: HR 80, BP 130/72, RR 18, Pox 96% (RA); otherwise normal. Labs: BMP normal, Hgb 12.8 g/dl. Which of the following is this patient’s strongest patient-specific predictor for postoperative pulmonary complications?