Large Study Links Meth Use and HIV Risk

From AIDSMeds.com

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April 5, 2007

By Tim Horn, Senior Writer & Editor

(AIDSmeds.com) - New study results have established methamphetamine use as an independent risk factor for HIV transmission and, when combined with other risk factors like unprotected receptive anal intercourse with multiple partners, the chances of seroconversion increases substantially. The new analysis, reported by researchers associated with the U.S.-based Multicenter AIDS Cohort Study (MACS), is to be published in a forthcoming issue of the Journal of Acquired Immune Deficiency Syndromes.

Methamphetamine is a powerful central nervous system stimulant that has been popular among men who have sex with men (MSM) for many years, notably due to its ability to prolong wakefulness, reduce inhibitions, and heighten sexual desire.

Several behavioral studies have demonstrated that MSM who use methamphetamine are more likely to engage in high-risk sexual practices, putting them at an increased risk for HIV and other sexually transmitted infections (STIs).

A notable criticism of many such studies is that they only demonstrate a high prevalence of HIV among methamphetamine users. In other words, while there may be high rates of HIV infection among MSM who have reported using methamphetamine – that is, a correlation between meth use and HIV infection among gay and bisexual men – these data do not support the hypothesis that there is causation (a causative role) between methamphetamine and HIV infection.

There have been a few studies examining the incidence of new HIV infections among meth users, compared to MSM who have never used the drug. Epidemiological data such as these are needed to establish causation. However, results from incidence studies have been limited, due to the small number of seroconversions documented and the self-reported data collected over short follow-up periods. These studies were also hobbled by inadequate data adjustments for additional HIV risk factors (e.g., other recreational drugs used and risky sexual activities with different partners) and limited geographic diversity (e.g., one U.S. city only).

To take a closer look at the causative link between methamphetamine and HIV seroconversion, researchers turned to data collected in the MACS. According to David Ostrow, MD, PhD, of the Chicago MACS Center and an author of the methamphetamine study, "the strength of the MACS is that it is a relatively stable population of gay and bisexual men that has been followed prospectively since 1984, at the very beginning of the scientific study of the natural history of AIDS, with additional men recruited in 1987 to 1988 and 2000 to 2001. Given the semi-annual visits at which both behavioral and medical, as well as HIV testing and assessment is performed, we can look at causal relationships between sexual or drug behaviors and seroconversion, even though the exact nature of that causality is not necessarily elucidated in the study."

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