These assessments include a baseline measurements of the person’s:

• "CD4 count" (the number of CD4 cells in a volume of blood),
• viral load (the amount of HIV in a volume of blood), and
• symptoms of advanced HIV disease.

Baseline measurements are used as reference points to monitor HIV infection and the effectiveness of drug therapy. There are several reasons why anti-HIV drugs are not always started at the time of diagnosis.

• First, starting treatment usually means a significant life style adjustment.
• Second, in addition to their desired effects, anti HIV drugs have serious side effects.
• Third, if the virus is not completely suppressed, drug resistance can develop.
• Fourth, once patients start drug treatment, they must continue to take anti-HIV drugs.

Patients usually start HIV drug treatment when:

• They are experiencing severe symptoms of HIV infection or have been diagnosed with AIDS,
• their viral load is 55,000 copies/ml or higher, and/or
• their CD4+T count is 200 cells/cubic millimeter or less.

The decision to begin therapy for asymptomatic patients with over 200 CD4+T cells is complex and must be made based on careful patient counseling and education. There are both advantages and disadvantages of starting therapy early and of delaying therapy.

Potential benefits of early therapy:

• Earlier suppression of the virus’s ability to replicate
• Preservation of immune function and prolongation of disease-free survival
• Lower risk of drug resistance with complete viral suppression
• Possible decrease in the risk of transmitting the virus to others
  

Potential risks of early therapy:

• Adverse effects of the drugs on quality of life, and the complexity of some regimens, leading to reduced adherence with therapy.
• Development of drug resistance due to less than optimal suppression of the virus
• Limitation of future treatment options due to premature use of available drugs
• Risk of transmission of the virus resistant to antiretroviral drugs
• Serious toxicities associated with some drugs
• Unknown length of effectiveness of available therapies
  

Potential benefits of delayed therapy:

• Avoidance of treatment-related negative effects on drug toxicities, and quality of life
• Preservation of treatment options
• Delay in the development of drug resistance
  

Potential risks of delayed therapy:

• Possibility of irreversible immune system damage
• Possibility that suppressing viral replication may be more difficult at a later disease stage
• Increased risk for HIV transmission to others during a longer untreated period
  

Instant Feedback:
A potential benefit of delaying antiretroviral therapy is decreasing the chance of developing drug resistance.

HIV can mutate or change form while a person is taking anti-HIV drugs. This may result in an HIV infection that cannot be controlled with certain medications. To help overcome drug resistance, combinations of drugs are used to more effectively suppress the virus. Combining antiretroviral drugs is known as "highly active antiretroviral therapy" or HAART.

HAART is a major factor in significantly reducing the number of AIDS deaths in the United States, and combination therapy has emerged as the preferred treatment for HIV infection. The goal of HAART is to reduce the amount of virus in the blood to low, or even undetectable levels, even though the virus is not gone. HAART usually involves a combination of three or more drugs. Despite the benefits of HAART, side effects associated with many antiretroviral drugs are severe. Therefore, it is vital that patients taking these drugs be followed closely by their health care providers. In general, taking only one or two drugs is not recommended, because any decrease in viral load is almost always temporary without three or more drugs. An exception is the use of zidovudine (Retrovir ®, AZT) alone or with other drugs during pregnancy, to reduce the risk of HIV transmission to the fetus.