ICAAC: "Older" HIV-Positive People Benefit from Treatment

By Tim Horn, Senior Writer & Editor, AIDSmeds.com

For "older" people diagnosed with HIV infection, a new study indicates that HIV drug treatment offers significant benefits in terms of reducing viral load and increasing CD4 (T4 cell) counts. However, the data reported at last week's 46th Interscience Conference on Antimicrobial Agents and Chemotherapy (ICAAC) in San Francisco also indicate that those 50 years of age or older diagnosed with HIV were more likely to progress to AIDS than those diagnosed at a younger age.

Older people face an increasing risk for HIV and other sexually transmitted diseases (STDs). According to the U.S. Centers for Disease Control (CDC), approximately 10% of all people diagnosed with AIDS in the United States – roughly 75,000 Americans – are 50 years of age or older. Because older people don't get tested for HIV on a regular basis, the CDC argues, the actual number may be even higher.

The CDC says there are many factors that contribute to the increasing risk of infection in older people. In general, older Americans know less about HIV, AIDS, and STDs than younger age groups, primarily because the elderly have been neglected by public health groups and organizations responsible for education and prevention messages. In addition, older people are less likely than younger people to talk about sex or drug use with their doctors, and many healthcare providers don't ask their older patients about sex or drug use. Finally, older people often mistake the symptoms of HIV and AIDS for the aches and pains of normal aging, so they are less likely to suspect HIV or to get tested.

For those who are diagnosed with HIV at an older age, there have been lingering questions as to whether or not HIV treatment is comparable to the results typically seen in younger people in terms of viral load decreases, CD4 count gains, and disease progression. To provide some answers, a team of Spanish researchers turned to the PISCIS cohort, a study of HIV-positive people in Catalonia and the Balearic Islands.

Between 1998 and 2004, PISCIS enrolled 500 people diagnosed with HIV at some point after their 50th birthday. They were compared to 4,000 people diagnosed with HIV before they reached their 40th birthday.

According to the study authors, there were statistically significant gender differences between the two groups – 84% of those 50 or older were male, compared to 75% of those younger than 40. The older participants were also more likely to have been infected with HIV via sexual activity (52% vs. 29%) and were less likely to be coinfected with hepatitis C (14% vs. 45%).

At the time of their diagnoses, the older patients had lower CD4 cell counts than younger patients (229 cells vs. 360 cells). What's more, the older patients were more likely to learn of their HIV diagnosis upon being diagnosed with an AIDS-related complication, compared to 20% of the younger patients. According to Gemma Navarro, PhD, of the Corporacio Parc Tauli in Barcelona and the primary author of the study, these differences were likely tied to HIV being diagnosed later in the course of infection in the older patients compared to the younger patients.

While there were no significant differences in average viral loads between the two groups prior to beginning treatment, the older study participants were more likely to have viral loads below 500 after one year of treatment (86% vs. 68%). After five years, 81% of the older patients on treatment and 73% of the younger patients on treatment had viral loads below 500. However, the difference between the two groups after five years was not statistically significant, meaning that it could have been due to chance.

CD4 cell count responses to treatment also differed between the two groups. After one year of treatment, the average CD4 cell count among the older patients on treatment was 350, compared to an average CD4 count of 449 among the younger patients on treatment. After five years of treatment, the average CD4 cell count among the older patients was 483, compared to 547 among the younger patients on treatment.

When the researchers looked at the actual change over five years of treatment, the CD4 count increased by an average of 254 cells in the older patients, compared to a 186 CD4 cell increase in the younger patients. In other words, Dr. Navarro said, CD4 cell count increases were notable in both groups, which would likely translate into a decreased risk of disease progression, regardless of a patient's age at the time of diagnosis.

While treatment appeared to be beneficial for both older and younger patients in PISCIS, older patients were still more likely to progress to AIDS. Death rates were also higher among the older patients during the six years of follow up (9% vs. 4%). While Dr. Navarro's group did not provide a breakdown of the causes of death, it was reported that the most important factor contributing to the increased risk of disease progression and death in the older patients was a diagnosis of AIDS upon entering the study. For those who did not enter the study with a diagnosis of AIDS, survival rates were similar among the older and younger patients.

In conclusion, this study demonstrated that significant reductions in viral load and CD4 cell counts are achieved in response to treatment in older HIV-positive people. While the higher rates of disease progression and shorter survival indicate the possibility of HIV infection being more dangerous to older people, Dr. Navarro suggested that prompt diagnosis of all those at risk for HIV infection will likely diminish many age-related differences.

Source:

Navarro G, Nogueras MM, Segura F, et al. HIV infection in older patients: clinical, immunological, virological features and response to combination antiretroviral therapy [Abstract H-1397]. 46th Interscience Conference on Antimicrobial Agents and Chemotherapy, San Francisco, 2006.

This content is written by the Founder & Writers of AIDSmeds.com, and reviewed by Dr. Howard Grossman, our Medical Editor.
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