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HIV may be growing more virulent
New findings indicate the average patient CD4 count at time diagnosis is declining.
WASHINGTON — The average CD4 cell counts among seroconverters at the time of diagnosis have decreased from the beginning of the HIV/AIDS epidemic to the present, according to study data.
These findings, presented at the 2008 ICAAC/IDSA Meeting, suggest that HIV may be adapting to the host and becoming more virulent.
Researchers from the TriService AIDS Clinical Consortium/Infectious Disease Clinical Research Program in Bethesda, Md. conducted the study. The objective was to determine whether CD4 cell counts at the time of seroconversion have changed over time. There were 1,944 participants in the study.
Findings
The researchers calculated the average CD4 cell counts at the time of diagnosis during four periods:
- 632 cells/mm3 during 1985-1990.
- 555 cells/mm3 during 1991-1995.
- 495 cells/mm3 during 1996-2001.
- 499 cells/mm3 during 2002-2004.
The average decline in cell counts was 133 cells/mm3 from the first period to the last. The researchers then adjusted for length of seroconverting window, time from positive HIV test to CD4 count, age, sex, race, enrollment site and HIV viral load when available. After these adjustments, there was a decline of 113 cells/mm3 from 1985-1990 to 2002-2004. During 1985-1990, 12% of seroconverters had CD4 cell counts less than 350. For the 2002-2004 period, that figure had increased to 25%, according to the researchers.
“Patients and providers should be aware that people infected with HIV may be presenting with lower CD4 counts during the course of the epidemic, despite being diagnosed at an early timepoint after infection,” Nancy Crum-Cianflone, MD, MPH, a research physician at TriService, told Infectious Disease News.
Crum-Cianflone said she encourages early and frequent testing as a way of preventing CD4 levels to decrease to dangerous levels after infection. “Many people believe that low counts only occur many years after HIV infection, and our data help to dispel this,” she said.
She also commented on the benchmark of 350 cells/mm3 as the point at which highly active antiretroviral therapy should begin. “HIV providers should be prepared to initiate HAART perhaps earlier than previously expected,” she said.
Documented seroconverters
A unique quality of this particular study is that all participants were documented seroconverters. “Without such a group the results would not be valid,” Crum-Cianflone said. “Our cohort was all military members who are screened for HIV on a regular basis.”
Because of this, the researchers were able to estimate the time of infection by using points between the last negative test and the first positive test. “This specific information on the timing of HIV infection was helpful,” Crum-Cianflone said. “With a different population, it is possible that patients simply may have been diagnosed later.”
This cohort allowed the researchers to more effectively control the statistical models for the timing of testing, according to Crum-Cianflone. – by Rob Volansky
For more information:
- Crum-Cianflone N, Eberly L, Zhang Y, et al. Is HIV becoming more virulent? Initial CD4 cell counts among HIV seroconverters across the HIV epidemic: 1985-2004. Presented at: the 2008 ICAAC/IDSA Meeting; Oct. 25-28, 2008; Washington.