San Francisco Study Shows Antiretroviral Treatment Continues To Improve AIDS Survival

"Our data show a very significant survival benefit from use of antiretroviral therapy, particularly when it includes a protease inhibitor," said Sandra Schwarcz, MD, MPH, the principal investigator of the study and a member of the SF Department of Public Health AIDS Surveillance Unit.

Schwarcz reported the findings today (July 13) at the XIII International AIDS Conference in Durban, South Africa.

The study included 2,607 persons who were diagnosed with one of the AIDS-defining opportunistic illnesses between 1995-97 and 3,228 persons diagnosed with either an opportunistic illness or low CD4 cell count within the same time period. Researchers analyzed survival trends over time in the first group of patients and looked at how various forms of treatment affected the risk of death in the latter group.

Because San Francisco was one of the first AIDS epidemic centers in North America, disease trends have often been observed first in the city, said Schwarcz. The number of AIDS deaths in San Francisco reached a plateau between 1992-94 and then declined in 1995, as highly active antiretroviral therapy (HAART) was introduced. The years 1996 and 97 saw the greatest (59 percent) decline in AIDS deaths in the city, but between 1997-98 the decline dropped to 30 percent, prompting speculation that the survival benefit associated with HAART might have waned.

To determine whether this was so, researchers at the San Francisco DPH AIDS Surveillance Unit and a UCSF colleague used comprehensive surveillance data to carefully evaluate trends in AIDS survival between 1995-97 and to assess the impact of treatment on the risk of death after AIDS.

The DPH AIDS surveillance registry includes detailed follow-up information on treatment and treatment outcomes, said Schwarcz. Working with this registry, researchers have access to information on the dates and types of AIDS-defining opportunistic illnesses, CD4 test results, and the types and starting dates of antiretroviral therapy and prophylactic medications. Information is collected on patients at the time of diagnosis and is updated annually.

In this study, researchers looked at survival in two ways: by determining the median (midpoint) time of survival for patients and determining the proportion of persons surviving two years after diagnosis. They found that survival increased by both measures in the three-year study period. Median survival was 24 months for persons diagnosed in 1995, 51 months for persons diagnosed in 1996, and could not yet be determined for persons diagnosed in 1997. The proportion of persons surviving two years after diagnosis was 50 percent for those diagnosed in 1995, 69 percent for those diagnosed in 1996, and 70 percent for those diagnosed in 1997.

The researchers also found that use of antiretroviral therapy reduced the risk of death, particularly if it included a protease inhibitor. Patients who received this type of therapy (HAART) after being diagnosed with AIDS, reduced their risk of death by 60 percent, said Schwarcz.

"This finding, combined with other data that predict little negative effect associated with drug resistance and the potential for reduced HIV transmission from persons receiving therapy, supports efforts to expand the use of HAART," said Schwarcz.

The study also determined that the risk of death was increased for persons aged 40 or greater at the time of AIDS diagnosis, for those whose initial AIDS diagnosis included an opportunistic illness, and for both homosexual and heterosexual injection drug users. The risk of death was lower for persons with higher CD4 cell counts at diagnosis.

Co-investigators included Ling Hsu, MPH, San Francisco DPH AIDS Surveillance Unit; Eric Vittinghoff, PhD, UCSF Center for AIDS Prevention Studies; Mitchell H. Katz, MD, director of the San Francisco DPH; and Willi McFarland, MD, PhD, San Francisco DPH HIV Seroepidemiology Unit and UCSF Center for AIDS Prevention Studies.