[1] UNIV OKLAHOMA, HLTH SCI CTR, DEPT MED, OKLAHOMA CITY, OK USA
[2] UNIV OKLAHOMA, HLTH SCI CTR, DEPT BIOSTAT & EPIDEMIOL, OKLAHOMA CITY, OK USA
[3] UNIV OKLAHOMA, HLTH SCI CTR, DEPT SURG, OKLAHOMA CITY, OK USA
[4] ST ANTHONY HOSP, OKLAHOMA CITY, OK USA
[5] UNIV CALGARY, DEPT MED, CALGARY, AB, CANADA