The vast majority of HIV-positive people older than 60 respond well to antiretroviral (ARV) therapy—achieving undetectable virus levels and substantial CD4 cell increases—according to a study published in the July 1 issue of the Journal of Acquired Immune Deficiency Syndromes.

Only a few large studies have documented how older HIV-positive people respond to ARV therapy compared with younger people living with the virus. Since experts project that more than half of HIV-positive people in the United States will be 50 and older by 2015, this lack of data is concerning—especially in light of the fact that some small studies have suggested that people who start ARVs at a later age might recover fewer CD4 cells.

To determine the impact of ARV therapy in older people, Luis Manrique, MD, and his colleagues at Rush University Medical Center in Chicago, reviewed the medical records of 191 people with HIV ages 60 and older. Manrique’s team separated the participants into two groups: 141 who were older than 50 at the time they were first diagnosed with HIV, and 50 who were 50 or younger at the time of diagnosis. The average age in the first group—those who’d been diagnosed after the age of 50—was 65, and the average duration of infection was eight years. The second group was slightly younger, on average, but had been infected for twice as long.

The two groups were similar in most respects, although the participants diagnosed when older than 50 were more likely to be coinfected with both HIV and hepatitis C virus (HCV). The older group also had lower CD4 counts before starting ARV treatment. Both groups, however, responded very well to treatment.

Seventy-six percent of the participants in both groups achieved undetectable virus levels after starting treatment. While groups also had significant increases in CD4 counts, with average increases of just less than 200 cells, those diagnosed after turning 50 had a trend toward poorer immune recovery.

There was a very high rate of coexisting medical conditions in both groups—68 percent had high blood pressure, 48 percent had high cholesterol, and roughly 25 percent had kidney disease or diabetes. The presence of these other medical conditions, however, did not appear to significantly reduce the positive impact of ARV therapy.

The authors note that the high treatment response rate was likely due at least in part to good adherence levels among those in the study, which confirmed previous research documenting better adherence among older people with HIV.

“Our single center study shows that with [ARV treatment], elderly HIV patients achieved successful immunologic and virologic outcomes despite a high rate of comorbidities,” concluded the authors. “The less robust [CD4] outcomes in older patients could be attenuated by earlier diagnosis and initiation of therapy.

“As this population ages,” they added, “the importance of managing other medical comorbidities will become increasingly important.”