摘要：Concurrent sexual partnerships may help to explain the disproportionately high prevalence of HIV and other sexually transmitted infections among African Americans. The persistence of such disparities would also require strong assortative mixing by race. We examined descriptive evidence from 4 nationally representative US surveys and found consistent support for both elements of this hypothesis. Using a data-driven network simulation model, we found that the levels of concurrency and assortative mixing observed produced a 2.6-fold racial disparity in the epidemic potential among young African American adults. Racial disparities in HIV/AIDS are large and growing, with an increasingly disproportionate burden borne by African Americans. Over time, disparities have emerged in every defined risk group, and some of the largest gaps exist among heterosexuals, particularly women. As noted in a recent Centers for Disease Control and Prevention (CDC) report focusing on cumulative diagnoses of HIV/AIDS from 2001 to 2005, the number of cases and diagnosis rates among Blacks were higher than those among all other racial/ethnic populations combined; Blacks also accounted for the largest percentage of HIV/AIDS diagnoses in every age group and almost every risk group. 1 The level of incidence of new HIV/AIDS diagnoses is greater among African American men, but racial disparities in incidence are greatest among African American women. Incidence rates among African American women not only exceed those of every other racial/ethnic group of women by 4- to 21-fold, they also exceed incidence rates among men in those groups. To understand what might be driving these disparities, it is helpful to consider the patterns observed in prevalence rates of other sexually transmitted infections (STIs). Table 1 shows estimates for a wide range of STIs derived from 3 national data sources; 1 is surveillance reports from the CDC, 2 and the other 2 are population based surveys: the National Health and Nutrition Examination Survey 3 and the National Longitudinal Survey of Adolescent Health (Add Health). 4 In the case of every STI, the disparity between African Americans and other groups is evident. The magnitude varies across the different pathogens, but the prevalence ratio between African Americans and Whites ranges from approximately 4 to more than 20. The only exception is human papillomavirus, which has a high prevalence in all instances and a prevalence ratio of 1.4. TABLE 1 Estimated Prevalence Rates of and Disparities in HIV and Other Sexually Transmitted Infections: Add Health, NHANES, and CDC Surveillance Data Prevalence (per 100 population) Survey (Age Range of Respondents) Non-Hispanic Blacka Non-Hispanic Whiteb Hispanicc Surveyd Prevalence Ratioe CDC Prevalence Ratioe Add Health 2000 (19–24 y) Chlamydia 12.5 1.9 5.9 6.5 6.0 Gonorrhea 2.1 0.1 0.2 21.8 24.9 Trichomoniasis 6.9 1.2 2.1 5.8 … HIV 0.5 …f …f 22.4 6.7 NHANES 2003–2004 Chlamydia (18–39 y) 5.2 1.3 2.6 4.2 6.5 Gonorrhea (19–39 y) 0.8 1.0 0.1 0.9 16.2 Human papillomavirus (14–59 y) 36.6 23.3 26.9 1.6 … Herpes simplex virus type 2 (14–49 y) 44.3 13.8 14.5 3.2 … Syphilis (18–49 y) 1.3 0.9 0.8 1.4 4.9 Trichomoniasis (14–49 y) 13.4 1.4 2.1 9.6 … HIV (18–49 y) 1.9 0.2 0.5 8.9 7.2 Open in a separate window Note . Add Health = National Longitudinal Survey of Adolescent Health; NHANES = National Health and Nutrition Examination Survey; CDC = Centers for Disease Control and Prevention. CDC surveillance data are based on the authors' tabulations, matched to the year of the survey, 2 , 50 and the closest age range possible from published tables in surveillance reports and bridged-race population estimates. 51 aAdd Health n = 3042; NHANES n = 503–735. bAdd Health n = 7741; NHANES n = 705–1256. cAdd Health n = 2340; NHANES n = 482–768. dAdd Health (top) or NHANES (bottom). eRatio of non-Hispanic Blacks to non-Hispanic Whites. fThere were too few cases in the survey to estimate prevalence by race for these groups. The combined prevalence of HIV for non-Hispanic Whites and Hispanics was 0.02. These disparities in STIs are also longstanding. CDC data on historical prevalence rates of gonorrhea and syphilis among people aged 15 to 19 years show strikingly large disparities dating back to 1981. 5 Equally striking, however, is how fast these disparities can change: rates of syphilis among non-Hispanic Blacks have dropped by more than 90% since 1990, and the prevalence ratio has decreased from more than 60 to approximately 5. 6
