Suppression of plasma viral load below 20 copies/ml is required to achieve a long-term response to therapy.
BACKGROUND
Current guidelines state that the goal of antiretroviral therapy for HIV-infected individuals is to suppress plasma viral load (pVL) to below 400 copies/ml.


METHODS
Predictors of achieving and maintaining pVL suppression were examined in a randomized trial of combinations of zidovudine, nevirapine and didanosine in patients with CD4+ T cell counts of between 200 and 600 x 10(6) cells/l who were naive to antiretroviral therapy and AIDS-free at enrolment.


RESULTS
One hundred and four patients had pVL > 500 copies/ml at baseline and a pVL nadir below 500 copies/ml. Of these, 77 patients experienced an increase in pVL above 500 copies/ml. The median number of days of pVL suppression to below 500 copies/ml was 285 (42) for patients with pVL nadir < or = (>) 20 copies/ml (P = 00.0001). The relative risk of an increase in pVL above 500 copies/ml associated with a pVL nadir below 20 copies/ml was 0.11 (P = 0.0001). The relative risks of an increase in pVL above 5000 copies/ml associated with a pVL nadir below 20 copies/ml or between 20 and 400 copies/ml were 0.05 [95% confidence interval (CI), 0.02-0.12] and 0.37 (95% CI, 0.23-0.61) respectively, compared with individuals with a pVL nadir > 400 copies/ml. Individuals with a pVL nadir < or = 20 copies/ml were at a significantly lower risk of virologic failure than individuals with a pVL nadir of between 21 and 400 copies/ml (P = 0.0001).


CONCLUSIONS
Our results demonstrate that suppression of pVL below 20 copies/ml is necessary to achieve a long-term antiretroviral response. Our data support the need for a revision of current therapeutic guidelines for the management of HIV infection.
Canadian HIV Trials Network and Centre for Excellence in HIV/AIDS, St Paul's Hospital/University of British Columbia, Vancouver.
J M
JM
Raboud
J S
JS
Montaner
B
B
Conway
S
S
Rae
P
P
Reiss
S
S
Vella
D
D
Cooper
J
J
Lange
M
M
Harris
M A
MA
Wainberg
P
P
Robinson
M
M
Myers
D
D
Hall
D019380:Anti-HIV Agents / Q000627:therapeutic use*; D001315:Australia; D018791:CD4 Lymphocyte Count; D002170:Canada; D016049:Didanosine / Q000627:therapeutic use; D004311:Double-Blind Method; D004359:Drug Therapy, Combination; D015658:HIV Infections / Q000188:drug therapy* / Q000821:virology; D015497:HIV-1; D006801:Humans; D007558:Italy; D009426:Netherlands; D019829:Nevirapine / Q000627:therapeutic use; D012367:RNA, Viral / Q000097:blood; D018894:Reverse Transcriptase Inhibitors / Q000627:therapeutic use*; D019562:Viral Load; D015215:Zidovudine / Q000627:therapeutic use
D019380:Anti-HIV Agents; D012367:RNA, Viral; D018894:Reverse Transcriptase Inhibitors; D015215:Zidovudine; D019829:Nevirapine; D016049:Didanosine