The geography of heterosexual partnerships in Baltimore city adults

Human immunodeficiency virus/sexually transmitted disease (HIV/STD) risk is determined in part by sexual network characteristics, which include spatial parameters. Geography and proximity of partner selection are important factors, which may explain neighborhood-level differences in HIV/STD morbidity. To study the effects of neighborhood factors on HIV/STD transmission in high-density urban areas, the geography of partner selection must be understood.

The Baltimore site of the National HIV Behavioral Surveillance system surveyed adults reporting one or more heterosexual partnerships. Spatial assortativity was defined as both partners residing in the same or adjacent census tracts and based on participant report. HIV core areas were defined as the census tracts in the top quartile for standardized HIV/AIDS case rates.

Participants (n = 307) provided data on 776 recent sexual partnerships, and geographic information were obtained for 510 partnerships (66%). Almost half (47%) reported choosing spatially assortative partners. Participants who lived in high HIV-prevalence areas were more likely to choose spatially assortative partners than residents of lower prevalence areas after adjusting for partnership type, gender, and number of partners. Although this population exhibited assortative mixing in all types of partnerships, racial and age assortativities were not associated with choosing spatially assortative partners.

Over 15 years ago, STD clinic patients in Baltimore were found to seek partners within close proximity. We confirm these results in a non-STD clinic population, indicating a continuing need for neighborhood approaches to intervention programs in urban areas.