Over time, changes in the natural history of a disease may occur due to viral evolution and other factors. However, little is known about changes in HIV disease severity since the start of the epidemic.

As described in the February 15, 2007 Journal of Infectious Diseases, researchers conducted a study to determine whether early post-seroconversion CD4 cell counts and HIV loads had changed over the course of the epidemic.

The analysis was based on data from 22 cohorts of HIV positive individuals with known dates of seroconversion from Europe, Australia, and Canada participating in the Concerted Action on Seroconversion to AIDS and Death in Europe (CASCADE) Collaboration. The investigators focused on patients who seroconverted between 1985 and 2002 and who had their first CD4 cell count (n = 3687) or HIV load (n = 1584) measurement within 2 years of seroconversion and before beginning antiretroviral therapy.

Results

• The overall median initial CD4 cell count was 570 cells/mm3 (interquartile range [IQR] 413-780 cells/mm3).

• The median initial HIV viral load was 35,542 copies/mL (IQR 7600-153,050 copies/mL, or 3.9-5.2 log10 copies/mL).

• During the study period, the post-seroconversion CD4 cell count fell by an average of 6.33 cells/mm3 per year (95% CI 8.47-4.20 cells/mm3) (P < 0.001).

• Over the same period, post-seroconversion viral load increased by 0.044 log10 copies/mL per year (95% CI 0.034-0.053 log10 copies/mL), or just over 10%.

• These trends remained after adjusting for potential confounding factors.

• The probability of progressing to a CD4 cell count below 500 cells/mm3 by 24 months after seroconversion increased from 0.66 (66%) for individuals who seroconverted before 1991 to 0.80 (80%) for those who seroconverted during 1999-2002.

Conclusion

"These data suggest that, in Europe, there has been a trend of decrease in the early CD4 cell count and of increase in the early HIV load," the authors concluded.

"Additional research will be necessary to determine whether similar trends exist in other geographical areas."

02/13/07

Reference
M Dorrucci, G Rezza, K Porter, and others. Temporal Trends in Postseroconversion CD4 Cell Count and HIV Load: The Concerted Action on Seroconversion to AIDS and Death in Europe Collaboration, 1985-2002. Journal of Infectious Diseases 195(4): 525-534. February 15, 2007.