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HIV and AIDS


The report of the Bandolier conference is now available. It can be found here on Bandolier 's web pages, or can be obtained from Eileen Neail by fax on +44 1865 226978. Some new information reinforces the evidence that plasma viral load predicts eventual outcome and is a useful surrogate marker, and that the newer combination therapies make a real difference in real practice.

Viral load and CD4 predict outcome

A study [1] of 664 seropositive injection drug users over eight years allowed the correlation of viral load (number of copies of HIV nucleic acid per mL of blood) and CD4 cells at diagnosis with eventual outcome of progression to AIDS and/or death due to an infectious disease. Of the 664 enrolled subjects 522 had sufficient samples from the initial diagnosis to allow the viral load test to be performed.

Five-year outcomes of progression to AIDS or infectious disease death according to CD4 and virus concentrations in blood
CD4 cell count
CD4 <200/µL CD4 200-490/µL CD4 ≥500/µL
Viral load (copies/mL) AIDS (%) Infectious disease death (%) AIDS (%) Infectious disease death (%) AIDS (%) Infectious disease death (%)
<500 8 0 0 0
500-9999 58 14 12 7 9 5
10,000-29,999 75 75 35 16 11 4
≥30,000 83 76 42 32 23 15
The results (Table) show an interplay between the two diagnostic factors. People with low CD4 counts and high viral loads do badly over a five-year follow up. Those with high CD4 counts and low viral loads do well. The evidence on the importance of HIV viral loads as a prognostic factor is accumulating ( Bandolier 41 ).

Combination therapies reduce disease progression

One of the questions posed about clinical trials is whether the results will be the same when the intervention goes into clinical practice. Arguments that they may not include different patient characteristics between trials and everyday practice, and treatment schedules in everyday practice not being the same as those used in clinical trials. An observational prospective study that included a large proportion of HIV-infected patients in Switzerland [2] indicated that, for HIV treatments, inclusion of new treatments in everyday practice produces startlingly good results.

The study involved 5200 participants enrolled since 1988. Since 1988 the proportion of patients having no treatment has fallen, with concomitant increases in patients having dual therapy (two antiretroviral drugs) or triple therapy (two antiretroviral drugs plus a protease inhibitor). The results (Figure) show that the use of more aggressive therapies led to reduced risk of progressing to AIDS and death. Even though the 95% confidence intervals in the Figure are wide for triple therapy, the trend is all in the right direction and is in accord with the results of randomised trials (see Bandolier 44 ).

References:

  1. D Vlahov, N Graham, D Hoover et al. Prognostic indicators for AIDS and infectious disease death in HIV-infected injection drug users. JAMA 1998 279: 35-40.
  2. M Egger, B Hirschel, P Francioli et al. Impact of new antiretroviral combination therapies in HIV infected patients in Switzerland: prospective multicentre study. BMJ 1997 315: 1194-9.



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