CD4 count at presentation for HIV care in the United States and Canada: Are those over 50 years more likely to have a delayed presentation? oleh Silverberg Michael J, Benson Constance A, Collier Ann C, Kirk Gregory D, Jacobson Lisa P, Martin Jeffrey N, Deeks Steven G, Sterling Timothy R, Rodriguez Benigno, Gill M John, Rourke Sean B, Napravnik Sonia, Eron Joseph J, Kitahata Mari M, Saag Michael S, Horberg Michael A, Bosch Ronald J, Hogg Robert S, Brooks John T, Klein Marina B, Gange Stephen J, Gebo Kelly A, Althoff Keri N, Goedert James J, McKaig Rosemary G, Thorne Jennifer, Rachlis Anita, Moore Richard D, Justice Amy C