Some recent studies, in STI and other journals, have sought to demonstrate the importance of spatial location as a determinant of STI prevalence in its own right (Haley & Cooper (STI); ‘Scoping Location’ (STI/blogs))). On the face of it, Brawner & Schensul appear to share this aim, in their comparative neighbourhood-based case study of multilevel factors affecting HIV transmission in four Philadelphia census-tracts. However, the most striking outcome reported in this paper (see also Brawner & Guthrie) are findings concerning the relationship of race and sex to the mode of HIV transmission.
Lacking the resources that would be required to study the entirety of Philadelphia, the authors try to cash out the influence of spatial location by restricting themselves to four census tracts, chosen on the basis of their representation of extremes of racial composition and HIV prevalence: a low-prevalence black area, a high-prevalence black area, a low-prevalence white area, and a high-prevalence white area. The variables of interest are: first, race and gender; second, income and insurance status. This allows the researchers to profile, in contrasting terms, the average HIV/AIDS-infected individual in the four areas.
As it turns out, the average HIV/AIDS-infected individual in the low-prevalence black area will be a poor, Medicaid/uninsured, black women who has been infected heterosexually; the average individual in the high-prevalence black area will be a poor, Medicaid/uninsured, black man, who has been infected heterosexually; in the low-prevalence white area, they will be a poor, Medicaid/uninsured white man who has been infected homosexually; while in the high-prevalence white area, they will be a relatively better-off, insured, man who has been infected homosexually.
As regards the stated aim of the study, the importance of location as a factor in its own right remains unclear. As in the case of Haley & Cooper (STI), location tends to dissolve on closer analysis into a ‘proxy’ for various other factors (e.g. race and prevalence). What does emerge very clearly, by contrast, is the importance of being able to take a ‘local’, as opposed to a national or global, perspective of the HIV/AIDS epidemic. As is well known, the vulnerability to HIV/AIDS of black MSM, as a group, is particularly serious (see ‘What is the potential of ‘treatment as prevention” (STI/blogs)). So, at a national level, a concentration on reducing incidence amongst MSM populations – and black MSM, in particular – makes a lot of sense. Yet what Brawner & Schensul bring home in this paper is, in certain areas, the importance of HIV-AIDS infected populations with a very different cultural and social profile – e.g. people who are black, heterosexual, sometimes women, and, more often than not, on Medicaid/without insurance.