[1] Harvard Univ, Sch Publ Hlth, Div Renal, Brigham & Womens Hosp, Boston, MA 02115 USA
[2] Harvard Univ, Sch Publ Hlth, Div Pulm, Massachusetts Gen Hosp, Boston, MA 02115 USA
[3] Harvard Univ, Sch Publ Hlth, Dept Nutr, Boston, MA 02115 USA
[4] Harvard Univ, Sch Publ Hlth, Dept Epidemiol, Boston, MA 02115 USA