Although community network studies show that sexual relationships occur between members of "risk groups" -- men who have sex with other men (MSM), people who inject drugs (PWID), non-injection drug users (NIDU) -- and heterosexuals, researchers at New York University's Center for Drug Use and HIV Research (CDUHR) note that little research has been done to help explain how HIV epidemics and programs in one population affect others and how to reduce the risks of transmission.
A recent study conducted by researchers from CDUHR, led by Samuel R. Friedman, Director of both CDUHR's Interdisciplinary Theoretical Synthesis Core, and the Institute for Infectious Disease Research at NDRI, sheds light on the pathways connecting HIV epidemics in different populations.
It shows that programs for people who use drugs - like syringe exchange, HIV counseling and testing, and drug abuse treatment - are associated with subsequent lower rates of AIDS incidence and death among heterosexuals.
"Since existing theory and research have relatively little to say about the cross-population processes being studied, we used exploratory analytic technique to study these relationships," explains Dr. Friedman.
The objective of the study, "Do metropolitan HIV epidemic histories and programs for people who inject drugs and men who have sex with men predict AIDS incidence and mortality among heterosexuals?" was to better understand how epidemics among MSMs and PWIDs correlate with later epidemics and mortality within heterosexuals; how prevention programs targeting specific groups affect future epidemics among other populations; and whether the size of MSM and PWID populations are associated with the later epidemics and mortalities among heterosexuals. The study was published in the Annals of Epidemiology.
The study looked at data from 96 large US metropolitan statistical areas (MSAs) from 1992 - 2008. "We have only limited ability to study the mechanisms by which our independent variables come to be associated with outcomes," explains Dr. Friedman. "Research into whether interventions in one key population affect HIV epidemics in other key populations is of high policy relevance and should be a priority."
Although the study highlights the necessity of future studies, it found that HIV counseling and testing in PWIDs was associated with lower AIDS incidence in heterosexuals, while counseling and testing in MSMs were not; and that availability of syringe exchange programs and drug abuse treatment programs were associated with lower AIDS death rates among heterosexuals.
The study also highlights a link between racial/ethnic residential segregation and rates of AIDS incidence and mortality among heterosexuals and points to evidence pairing social causations like income inequality with mortality.
"Our findings are descriptive of the relationships of the measured variables in these large metropolitan areas," said Dr. Friedman. "They do not, however, imply that these findings can necessarily be extended to smaller MSAs, non-metropolitan localities, other time periods or other countries, for that further research is clearly needed."