MedicalResearch.com Interview  Dongyi (Tony) Du, MD, PhD Division of Epidemiology FDA/CDRH/OSB Medical Research: What are the main findings of the study? Dr. Du: The risk for death on the date of surgery was 60% higher for recipients of mechanical aortic valves than recipients of bioprosthetic aortic valves (OR, 1.61 [95%CI, 1.27-2.04; P < .001]; risk ratio [RR], 1.60). The risk difference decreased to 16% during the 30 days after the date of surgery (OR, 1.18 [95%CI, 1.09-1.28; P < .001]; RR, 1.16). The risk for operative mortality was 19% higher for recipients of mechanical compared with bioprosthetic valves (OR, 1.21 [95%CI, 1.13-1.30; P < .001]; RR, 1.19). The number needed to treat with mechanical valves to observe 1 additional death on the surgery date was 290; to observe 1 additional death within 30 days of surgery, 121. (more…)