Australian researchers have reported that AIDS
dementia is now being diagnosed at higher CD4 counts than in the pre-HAART era -
a median CD4 clevel of 170 in 1998, compared with 70 cells in 1992. A larger
proportion of people were diagnosed with AIDS dementia as their AIDS defining
illness in the period after the introduction of HAART compared with 1992-1995,
the group report (6.5% vs 4.4%). They suggest that HAART may not have had the
same impact on rates of ADC as it has done on other AIDS-related illnesses. The
overall number of AIDS diagnoses in New South Wales declined from 1049 in 1994
to 367 in 1997, suggesting a sharp fall in the incidence of AIDS dementia,
despite the increasing proportion of people who developed it as an AIDS defining
illness.
However, in London, researchers have found that the
incidence of AIDS dementia amongst individuals diagnosed with AIDS attending
London's largest treatment centre declined by 90% between 1994 and 1996, from
4.4% to 0.4%. Dr Jose Catalan of Chelsea and Westminster Hospital was due to
report his findings at AIDS Impact, the Fourth International Conference on
Psychosocial Aspects of AIDS, in Ottawa on July 17.
Dr Greg Dore of the University of New South Wales
cautioned that AIDS dementia complex is not increasing in frequency in
Sydney.
"The main message from our paper should not be that
ADC is increasing" he told aidsmap.com. "The absolute numbers
of ADC cases are 1992 (35), 1993 (43), 1994 (56), 1995 (36), 1996 (44), 1997
(29). So there is no evidence for an increase in numbers, but the AIDS epidemic
peaked in Australia in 1994, and even without improved therapies we would have
expected a declining incidence of AIDS in general, and ADC in a specific sense.
Almost all AIDS illnesses have declined since 1995, but, the question was, has
ADC declined as much as the others? We have assessed that by looking at the
proportion of all initial AIDS-defining illnesses which ADC makes up. This is
not the ideal methodology for answering this question, as it only includes
initial AIDS illnesses. A cohort study, with all AIDS illness events recorded
would have been preferable. But, given this limitation, there was a suggestion
that the decline in ADC is relatively less marked, because it increased as a
proportion of initial AIDS illnesses from 4.4% (1992-1995) to 6.0% (1996) and
6.5% (1997). Again, this is not an absolute increase, but, a relative increase
compared to all other AIDS illnesses".
The Sydney group attributes the relative increase in
AIDS-defining cases of ADC partly to better surveillance, with improved ability
amongst doctors to recognise the syndrome, and greater vigilance due to concerns
that HAART may not always protect the central nervous system against HIV-related
damage. However, data on the relative incidence of ADC in treated and untreated
patients was not available, making any analysis of the protective effects of
HAART impossible.
AIDS 1999;13:1249-1253.