Old habits die hard. Since the 1980s, when we first came to understand that CD4 cell depletion is one of the hallmarks of immune deficiency in persons with AIDS, we clinicians have checked the CD4 counts of our stable patients every 3 months (more often for those who were sick or starting new therapy). Our patients (and we) worried from visit to visit whether their CD4 counts (we called them T-cells then) rose or dropped (mostly they dropped), and our spirits rose and fell with their counts.
Katz MH. Directing Resources to Where They Are the Most Needed. JAMA Intern Med. 2013;173(18):1748. doi:10.1001/jamainternmed.2013.8590