CD4 and AIDS: In a recent study by Althoff and colleagues of 44,491 HIV-infected patients enrolled in the North American-AIDS Cohort Collaboration on Research and Design (NA-ACCORD), the median CD4 count at first presentation to HIV care increased from 256 cells/mm3 (interquartile range, 96–455 cells/mm3) to 317 cells/mm3 (interquartile range, 135–517 cells/mm3) from 1997 to 2007 (P < 0.01).