Objectives: To assess whether AIDS cases in Australia have been diagnosed at higher CD4 counts since the widespread availability of highly active antiretroviral treatment (HAART) in mid-1996.
Methods: Data on the CD4 count at AIDS diagnosis for AIDS cases diagnosed between 1 January 1992 and 31 December 1997, and reported to the National AIDS Registry in Australia by 31 March 1998, were analysed. The median CD4 count at AIDS diagnosis, and the proportions of AIDS diagnoses with a CD4 count above 100 cells/microl, and above 200 cells/microl, were calculated by the year of diagnosis, both for all AIDS-defining illnesses, and for each illness separately. Analyses were also stratified by the time interval between HIV and AIDS diagnoses (less than or equal to, or more than, 3 months) because people diagnosed with HIV close to the diagnosis of AIDS would generally not have received any antiretroviral treatment before the diagnosis of AIDS, and so no trends in CD4 counts at the diagnosis of AIDS would be expected in this group.
Results: There was an increase in CD4 count at AIDS diagnosis in 1996 and 1997, although this increase was only apparent for AIDS-defining illnesses other than Pneumocystis carinii pneumonia (PCP), and was limited to AIDS cases diagnosed with HIV more than 3 months before AIDS. In cases of AIDS other than PCP, and diagnosed with HIV more than 3 months before AIDS, the median CD4 count increased from 50 cells/microl in 1995 to 80 cells/microl in 1996 and 134 cells/microl in 1997.
Conclusions: There has been an increase in the CD4 count at AIDS diagnosis for most AIDS-defining illnesses in Australia coincident with the widespread availability of HAART.