[1] BRIGHAM & WOMENS HOSP, CONSOLIDATED DEPT MED, DIV CLIN EPIDEMIOL, 75 FRANCIS ST, BOSTON, MA 02115 USA
[2] YALE NEW HAVEN MED CTR, NEW HAVEN, CT 06504 USA
[3] YALE UNIV, SCH MED, NEW HAVEN, CT 06510 USA
[4] UNIV CINCINNATI HOSP, CINCINNATI, OH USA
[5] HARVARD UNIV, SCH MED, BOSTON, MA 02115 USA