Clinical Manual for Management of the HIV-Infected Adult
2006 Edition

Section 1: Testing and Assessment

Determining Risk of HIV Progression

Background

The absolute CD4 cell count and CD4 percentage are used for disease staging, and to determine when to start antiretroviral therapy (ART) and prophylaxis against opportunistic infections. The HIV RNA level (viral load), when used in conjunction with the CD4 count, also provides prognostic information in patients who are naive to ART.

Data from various cohort studies have demonstrated the strong relationship between lower CD4 count or higher viral load and the risk of progression to AIDS. Tables 1 and 2 and Figure 1 below show the risk of disease progression and death in patients who have not been treated with ART and in patients starting ART in several North American, European, and Australian cohorts. The data consistently indicate the importance of initiating ART before the CD4 count declines to <200 cells/µL, if possible.

Table 1. Relationship between CD4 Count or Viral Load and AIDS Progression

CD4 Count (cells/µL) Viral Load (copies/mL) AIDS Progression in Men (%) Over 3 Years Over 9 Years <200 <10,000 14% 64% 10,000-30,000 50% 90% >30,000 86% 100% 200-350 <10,000 7% 66% 10,000-30,000 36% 85% >30,000 64% 93% >350 <10,000 7% 54% 10,000-30,000 15% 74% >30,000 40% 85%

Adapted from: Mellors JW, Rinaldo CR Jr, Gupta P, et al. Prognosis in HIV-1 infection predicted by the quantity of virus in plasma. Science. 1996 May 24;272(5265):1167-70.

Table 2. Predicted 6-Month Risk of AIDS according to Age and Current CD4 Cell Count and Viral Load, Based on a Poisson Regression Model

Predicted Risk (%) at Current CD4 cell Count (x 106 cells/L)* Viral Load (copies/ml) 50 100 150 200 250 300 350 400 450 500 Age 25 years 3,000 6.8 3.7 2.3 1.6 1.1 0.8 0.6 0.5 0.4 0.3 10,000 9.6 5.3 3.4 2.3 1.6 1.2 0.9 0.7 0.5 0.4 30,000 13.3 7.4 4.7 3.2 2.2 1.6 1.2 0.9 0.7 0.6 100,000 18.6 10.6 6.7 4.6 3.2 2.4 1.8 1.4 1.1 0.8 300,000 25.1 14.5 9.3 6.3 4.5 3.3 2.5 1.9 1.5 1.2 Age 35 years 3,000 8.5 4.7 3.0 2.0 1.4 1.0 0.8 0.6 0.5 0.4 10,000 12.1 6.7 4.3 2.9 2.0 1.5 1.1 0.9 0.7 0.5 30,000 16.6 9.3 5.9 4.0 2.8 2.1 1.6 1.2 0.9 0.7 100,000 23.1 13.2 8.5 5.8 4.1 3.0 2.3 1.7 1.3 1.1 300,000 30.8 18 11.7 8.0 5.7 4.2 3.1 2.4 1.9 1.5 Age 45 years 3,000 10.7 5.9 3.7 2.5 1.8 1.3 1.0 0.7 0.6 0.5 10,000 15.1 8.5 5.4 3.6 2.6 1.9 1.4 1.1 0.8 0.7 30,000 20.6 11.7 7.5 5.1 3.6 2.6 2.0 1.5 1.2 0.9 100,000 28.4 16.5 10.6 7.3 5.2 3.8 2.9 2.2 1.7 1.3 300,000 37.4 22.4 14.6 10.1 7.2 5.3 4.0 3.1 2.4 1.9 Age 55 years 3,000 13.4 7.5 4.7 3.2 2.3 1.7 1.2 0.9 0.7 0.6 10,000 18.8 10.7 6.8 4.6 3.3 2.4 1.8 1.4 1.1 0.8 30,000 25.4 14.6 9.4 6.4 4.6 3.3 2.5 1.9 1.5 1.2 100,000 34.6 20.5 13.3 9.2 6.5 4.8 3.6 2.8 2.2 1.7 300,000 44.8 27.5 18.2 12.6 9.1 6.7 5.0 3.9 3.0 2.4

*Shading distinguishes risk: <2%, no shading; 2-9.9%, light gray; 10-19.9%, mid-gray; > 20%, darkest gray. Reprinted with permission from Lippincott, Williams & Wilkins [Phillips A; CASCADE Collaboration. Short-term risk of AIDS according to current CD4 cell count and viral load in antiretroviral drug-naïve individuals and those treated in the monotherapy era. AIDS 2004; 18 (1):51-8]. Lippincott, Williams & Wilkins home page: http://lww.com

References

• Egger M, May M, Chene G, et al. Prognosis of HIV-1-infected patients starting highly active antiretroviral therapy: a collaborative analysis of prospective studies. Lancet. 2002 Jul 13;360(9327):119-29.
• Hare CB. Clinical Overview of HIV Disease. In: Peiperl L, Coffey S, Volberding PA, eds. HIV InSite Knowledge Base [textbook online]; San Francisco: UCSF Center for HIV Information; 2004. Accessed February 7, 2006. Available online at hivinsite.ucsf.edu/InSite?page=kb-03-01-01.
• Mellors JW, Rinaldo CR Jr, Gupta P, et al. Prognosis in HIV-1 infection predicted by the quantity of virus in plasma. Science. 1996;272:1167-70.
• Phillips A. CASCADE Collaboration. Short-term risk of AIDS according to current CD4 cell count and viral load in antiretroviral drug-naïve individuals and those treated in the monotherapy era. AIDS. 2004;18(1):51-8.
• U.S. Department of Health and Human Services. Guidelines for the Use of Antiretroviral Agents in HIV-1-Infected Adults and Adolescents. May 4, 2006. Available online at aidsinfo.nih.gov/Guidelines/GuidelineDetail.aspx?GuidelineID=7.