Increased Risk of AIDS-defining Illnesses Seen Even at CD4 Counts of 500-750

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HIV positive people with CD4 T-cell counts in the 500-749 cells/mm3 range still have a higher risk of AIDS-defining illnesses -- especially cancers -- compared to those with more than 1000 cells/mm3, although the risk is quite low, according to a study published in the August 6, 2013, advance edition of Clinical Infectious Diseases. These findings offer further evidence of the benefits of prompt antiretroviral treatment.

It is well known that the incidence of opportunistic infections and cancers rises steeply once a person's CD4 count falls below 200 cells/mm3. The risk of HIV disease progression and death increases below 350 cells/mm3 as well, with smaller disadvantages apparent below 500 cells/mm3 -- the lower end of the normal range for healthy HIV negative people. Outcomes among HIV positive people with higher CD4 levels, however, have not been extensively studied. Current U.S. antiretroviral therapy (ART) guidelines recommend that anyone diagnosed with HIV should be offered treatment, regardless of CD4 count.

Amanda Mocroft andfellow investigators with the EuroCOORD Collaboration of Observational HIV Epidemiological Research Europe (COHERE) study team looked at occurrence of AIDS-defining conditions among cohort participants at different CD4 cell strata: 200-349, 350-499, 500-749, 750-1000, and >1000 cells/mm3.

The analysis included 207,539 cohort participants age 14 or older with at least 1 CD4 cell measurement of >200 cells/mm3 between 1998 and 2010. Collectively they contributed more than 1 million person-years (PY) of follow-up data.

Results

o   20.5 per 1000 PY for people with 200-349 cells/mm3;

o   10.2 per 1000 PY for those with 350-499 cells/mm3;

o   6.4 per 1000 PY for those with 500-749 cells/mm3;

o   4.7 per 1000 PY for those with 750-999 cells/mm3;

o   4.1 per 1000 PY for those with >1000 cells/mm3.

"The incidence of AIDS-defining illnesses was higher in individuals with a current CD4 count of 500-749 cells/[mm3] compared to those with a CD4 count of 750-999 cells/[mm3], but did not decrease further at higher CD4 counts," the study authors concluded.

"Results were similar in patients virologically suppressed on combination antiretroviral therapy, suggesting that immune reconstitution is not complete until the CD4 increases to >750 cells/[mm3]," they added.

8/28/13

Reference

A Mocroft, HJ Furrer, JM Miro, et al (COHERE study in EuroCOORD). The Incidence of AIDS-Defining Illnesses at a Current CD4 Count >200 Cells/µL in the Post–Combination Antiretroviral Therapy Era. Clinical Infectious Diseases. August 6, 2013 (Epub ahead of print).