Meeting Explores Gender Differences in Viral Load
The issue of gender differences in viral load gained momentum in December 1998 when a major study reported that women may progress to AIDS with half the viral level of men. Since then conflicting findings about possible differences in viral load between women and men have emerged.
A driving question of the meeting was, "Is there enough evidence to conclude that there is a gender difference in viral load?" Based on an extensive research review, meeting participants concluded that observed differences in viral load are real and present in the first several years of HIV infection and disease. These differences may lessen or disappear within five years after initial HIV infection. Data were conflicting as to whether gender differences persist after the first five years of HIV infection. Some studies suggested they do, while others seemed to show that they do not.
The significance of these differences remains unknown. Because of this and because there is increasing debate about the best time to start anti-HIV therapy, the meeting concluded that, at this time, recommendations for treating HIV-positive women should not be changed. In essence, recommendations should remain the same for both men and women. However, participants agreed that discussion of these differences should be significantly expanded in the Federal Guidelines for using anti-HIV therapy and should be taken into consideration when starting treatment.
Attempts to identify and describe causes for gender differences in viral load were discussed. Many gaps exist in our understanding of gender differences in HIV disease -- not only in viral load, but also in CD4+ cell count and dynamics, and the effect of sex hormones on these various measures.
Not surprisingly, hormonal cycles were suggested as a possible cause for differences in viral load. Despite new information describing viral load variation during the ovulatory cycle, meeting participants agreed that there simply were not enough data to support a conclusion that hormones caused these observed differences. However, further research is needed in this important area.
Underscoring this need were compelling data presented from the Women and Infants Transmission Study. It showed that viral load is consistently lower (though not to a statistically significant degree) in infant girls than boys. Infancy is a time when the hormonal environment is similar in both females and males, suggesting that something other than hormones influences these viral load differences. However, in the last three months of pregnancy, baby boys are exposed to a surge of testosterone. It is unknown whether this may affect a boy's viral load.
Finally, researchers highlighted the fact that there appeared to be race and ethnicity differences in viral load which may confuse and further complicate the picture. In short, African Americans and Latinos appear to have lower viral levels than Caucasians. These findings stress the need to consider race and ethnicity as well as gender when studying viral load differences and HIV disease progression in general.
Some of the scientific goals identified for future exploration include:
CommentaryIn order to answer the many important questions borne out of the meeting, more women need to be enrolled in studies. Moreover, to determine clear differences between gender, more men of color need to participate in studies as well. Current studies and networks should be used to address these issues and maximize findings. New initiatives and collaborations -- particularly between basic science and clinical researchers -- focusing on gender, racial and ethnic differences in HIV disease markers and progression need to be forged.
It is important to consider that there are no reports of increased survival based on gender alone. Still, varied access to healthcare and HIV treatment places many women at a disadvantage. Finally, race, ethnicity, socioeconomic background, age and co-infections must also be considered as factors that may influence differences in viral load, CD4+ cell counts and rates of disease progression.
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