Althoff KN, Gebo KA, Gange SJ, Klein MB, Brooks JT, Hogg RS, Bosch RJ, Horberg MA, Saag MS, Kitahata MM, Eron JJ, Napravnik S, Rourke SB, Gill MJ, Rodriguez B, Sterling TR, Deeks SG, Martin JN, Jacobson LP, Kirk GD, Collier AC, Benson CA, Silverberg MJ, Goedert JJ, McKaig RG, Thorne J, Rachlis A, Moore RD, Justice AC, for the North American AIDS Cohort Collaboration on Research and Design. 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? AIDS Research And Therapy 2010, 7: 45. PMID: 21159161, PMCID: PMC3022663, DOI: 10.1186/1742-6405-7-45.Peer-Reviewed Original Research