Using CD4 lymphocyte count to predict survival with HIV infection

EDITOR, - Andrew N Phillips and colleagues used the CD4 lymphocyte count to predict long term survival after HIV infection in men with haemophilia,1 but the biological variables that influence the CD4 count limit the applicability of their results to other risk groups - for example, homosexual men.

I studied 25 HIV positive patients who had been followed up for more than six years in my clinic. Eleven were homosexual men, of whom three died of AIDS and three others developed AIDS during the follow up; one patient had a low CD4 lymphocyte count (100×10⁶/l, but the four others remained asymptomatic with counts of over 300×10⁶/l. Nine patients had been injecting drug users: two of these died in the sixth and seventh years after diagnosis while the rest remained asymptomatic with CD4 lymphocyte counts of over 300×10⁶/l during the six years of follow up. The five other patients were either haemophilic or thought to have been infected through blood transfusion. One of these died after 10 years and one had a CD4 lymphocyte count of 50×10⁶/l, but the three others were asymptomatic with counts of over 500×10⁶/l.

A linear decline in the CD4 lymphocyte count is not seen in all homosexual men who are HIV positive. After an initial drop in the count at the time of seroconversion there is either a gradual downward slope or, after a variable period, a much steeper slope with flattening of the curve when it drops below 50×10⁶/l. The repeated antigenic stimulation of CD4 cells infected with HIV and of coinfections - for example, with herpes simplex virus, hepatitis B virus, or cytomegalovirus - may account for the wide variation in survival in homosexual men. The use of antiretroviral agents and prophylactic treatment of opportunistic infection will further alter the natural course of events.