Adimora, Adaora A. MD, MPH; Schoenbach, Victor J. PhD; Martinson, Francis E.A. MB, ChB, MPH, PhD; Donaldson, Kathryn H. MPH; Stancil, Tonya R. MS, PhD; Fullilove, Robert E. EdD
Rates of heterosexually transmitted HIV infection in the United States are dramatically higher among African Americans than whites. 1 This disparity is especially pronounced in the rural Southeast, but no published epidemiologic studies of newly reported cases exist from this population. We have recently proposed that a part of the explanation for these marked racial disparities lies in the nature of sexual networks among African Americans. 2,3
The concept of sexual networks refers to a group of people who are linked directly or indirectly through sexual contact. 4,5 Sexual networks play a critical role in the population spread of sexually transmitted infections (STIs). 6–12 African Americans and whites appear to have largely separate and substantially different sexual networks. 13 One important difference in networks is the extent of participation in concurrent sexual partnerships (partnerships that overlap in time), as this pattern permits more rapid spread of infection through a connected population than does a pattern of serial monogamy with the same rate of formation of new partnerships, a key determinant of the reproductive number for new cases. 14,15 Analysis of data from the National Survey of Family Growth (NSFG) indicates a substantially higher crude prevalence of concurrent partnerships (21%) among African American women than among the general population of US women (12%), a difference that appears largely due to the markedly lower marriage rates among black women. 3
To explore further the potential for differences in sexual network patterns that could account for the higher rate of HIV in African Americans, the University of North Carolina (UNC) Rural Health Project studied heterosexual HIV transmission among African American men and women in rural North Carolina, a region experiencing a relatively high rate of heterosexually acquired HIV infection. The 5-year concurrency prevalence among black men and women from this region's general population was substantially higher (38%) than we found for black women in the NSFG. 16 In the present report we examine concurrent partnerships among African Americans with newly reported heterosexually acquired HIV infection.
Study participants were African American men and women between the ages of 18–59 years who had been reported to the North Carolina HIV/Sexually Transmitted Disease (STD) Prevention and Care Section within the preceding 6 months because of HIV infection and who denied male same-sex activity and injection drug use. People who are reported because of HIV infection have already received their HIV diagnosis and post-test counseling from their care provider but undergo additional counseling by North Carolina Disease Intervention Specialists (DIS). During the course of this counseling the DIS explained the study to eligible clients and obtained signed permission for release of name and contact information so that study staff could contact them to discuss participation. The study area included almost all of central and eastern North Carolina; much of this region is rural. Enrollment took place during January 1997 through March 2000.
Each prospective study participant was sent a letter with information about the study. A female African American nurse-interviewer then telephoned or, if a working telephone number could not be found, went directly to the prospective participant's home.
The interviewer requested permission to discuss the study, obtained signed consent, conducted a 1-hour interview in the participant's home or the interviewer's car, drew a blood specimen for performance of syphilis tests and other laboratory assays (results not reported in this document), and provided a $50 cash incentive. The standardized interview questionnaire was developed from questionnaires used in published studies and was carefully pretested and piloted. It covered sexual partnerships, HIV risk behaviors, STD history, health care access, and demographic information. Information was collected with respect to the participant and the participant's sex partners in the past 10 years, with additional detail concerning the last 3 sex partners. A federal certificate of confidentiality was obtained, and interviewers assured participants of absolute confidentiality and that their names would be erased following data cleaning, the only exception being a report to the local health department if their serologic analysis disclosed current syphilis infection. Data collection was approved by the UNC School of Medicine's Committee on the Protection of the Rights of Human Subjects.
Data were entered twice and reviewed for consistency. A computer algorithm, using methods previously described, 3 compared dates of first and last sexual intercourse with the 3 most recent sexual partners to identify overlapping (“concurrent”) partnerships (date of first sexual intercourse with one partner occurred before date of last intercourse with another partner).
We examined the association of concurrent partnerships with the following potentially explanatory variables: age at time of interview; age at first sexual intercourse; gender; marital status; annual household income <$16,000 (1996–1999); less than a high school education; personal history of incarceration >24 hours; history of incarceration of at least 1 of last 3 partners for >24 hours; lifetime number of sexual partners; number of partners during the past year; respondent's belief that at least 1 of the last 3 partners had had sex with others during the course of his or her sexual relationship with the respondent; partner's diagnosis of an STD during the course of the relationship with the respondent; partner's drug use, partner's history of trading sex; respondent's history of trading sex for drugs, money, or housing; and respondent's alcohol use and history of either smoking crack or snorting cocaine.
Analyses were performed separately for men and women, and results were combined where they were similar. Distributions of continuous variables were compared with the Wilcoxon rank sum test; homogeneity of odds ratios was assessed with the Breslow-Day statistic. We used stratified analyses and multiple logistic regression models with concurrency during the preceding 5 years as the dependent variable. The above-listed potential explanatory variables were included in the models before model reduction through stepwise backwards elimination. Respondent's history of trading sex and number of sexual partners were not included in the models because these variables are in a causal pathway for concurrency. Income was not included in the analysis because 19% of respondents did not provide income data.
SAS (versions 6.12 and 8.2, SAS Institute, Cary, NC) was used for data management and analyses.
DIS provided to study staff 1,236 HIV case reports, stripped of identifying information, for North Carolina residents age 18–59 years old whose HIV infection was first reported no more than 6 months prior to the start of the study. Over three-fourths (78%) were African Americans. Of 493 apparently eligible cases (based on age group, report date, and risk factors), DIS interviewed 482. Of these, 235 declined to have contact information released to the study, and 4 were not referred for unknown reasons. Consent rates were similar for women (49%) and men (44%) and declined slightly with age (53% for case subjects younger than 25 years, 47% for those 40 years and older). Consenting women were slightly younger than nonconsenting women; consenting men were slightly older than nonconsenting men. Of the 243 (50%) cases referred to the study, 17 ultimately proved ineligible (11 subsequently reported a history of injection drug use or sex with another man, 5 were referred >6 months after their HIV infection was reported, and 1 had uncertain HIV status). Ten could not be located, 7 were unavailable for reasons such as illness or incarceration, and 3 declined to participate after learning more about the study. The remaining 206 were interviewed, and their data were included in the study.
Respondents were mostly female, unmarried, and poor (Table 1). Of the 147 respondents who reported their income, 99 (67%) reported annual household income <$16,000 and 121 (82%) <$25,000. Fifty-nine percent of participants were high school graduates or had equivalency degrees; only 4% had finished college. More than half of the men (64%) and one-quarter of the women reported a history of incarceration for >24 hours.
Median lifetime number of partners was higher among men (20) than women (8.5) (Table 1). Over half (54%) of respondents reported having had >1 partner during the preceding year. About 25% of women and men, respectively, reported at least 3 and 4 partners during the preceding year (data not shown). Substantial minorities had a partner who had exchanged sex for drugs or money (32%) or had done so themselves (31%). Similarly, nearly half (48%) believed it very likely that at least 1 of their last 3 partners had smoked crack cocaine, and 31% had smoked crack themselves. Forty-four percent of respondents had had >5 drinks of alcohol in 1 day during the past 10 years. Eighty-six percent reported having had sex without a condom on >10 occasions with at least 1 of their last 3 partners.
Forty percent (95% CI: 34–47%) of respondents reported partnership dates that overlapped during the past year and 60% (95% CI: 53–66%) that overlapped during the past 5 years (Table 2). In the crude analysis, women (1 year: 37%, 95% CI: 20–46%; 5 years: 58%, 95% CI: 49–66%) were nearly as likely to report concurrent partnerships as were men (1 year: 45%, 95% CI: 34–56%; 5 years: 63%, 95% CI: 52–74%). Our concurrency classification was essentially concordant with respondents' own perceptions, since there was good agreement (κ = 0.51, 95% CI: 0.39–0.63) between concurrency status computed from partnership dates and respondents' self-report of having engaged in concurrent partnerships during the preceding 5 years. Similarly, a high proportion (men, 82%; women, 89%) believed it very likely that at least 1 of their last 3 partners had sex with others while in a sexual relationship with the respondent.
Unmarried men were most likely to have had concurrent partnerships (prevalence odds ratio = 3.9; 95% CI: 1.3–12.1). The relation between income and concurrency was weak and imprecise, due to missing data. Lack of a high school education was associated with greater prevalence of concurrency only in women (prevalence odds ratio = 2.1; 95% CI: 1.0–4.3). Respondents with concurrent partnerships were somewhat younger (median age 35 years for men, 30 years for women) than were those whose partnerships did not overlap (median age 39 years for men, Z = 2.0, P = 0.05; 32 years for women, Z = 2.5, P = 0.01, 2-sided, Wilcoxon tests). Concurrency prevalence was greater for men, and especially for women, reporting a history of incarceration. The relationship was also observed for men and women with a partner who had been incarcerated.
Prevalence of concurrency varied with sexual and risk behaviors. Although the median number of partners during the past year was the same for men with and without concurrency, examination of the distributions for partner number during lifetime and in the past year revealed that for both men and women, respondents with concurrency had more partners than those without concurrency. The data did not demonstrate an association between younger age at first sexual intercourse and concurrency (concurrent women = 15 years, nonconcurrent women = 16 years, Z = 1.8, P = 0.07; both concurrent and nonconcurrent men = 15 years, Z = 0.14, P = 0.9, Wilcoxon tests). In contrast, respondents who had had concurrent partnerships were more likely to have exchanged sex for drugs or money, smoked crack, or reported binge alcohol consumption within the past 10 years.
Multiple Logistic Analysis
The multiple logistic model identified 4 variables as able to account for variation in concurrency prevalence: male sex (odds ratio: 2.5; 95% CI: 1.2–5.2), age (1.4 per 5-year decrease in age; 95% CI: 1.2–1.6), history of smoking crack (2.5; 95% CI: 1.2–5.1), and incarceration of any of the respondent's last 3 partners (2.7; 95% CI: 1.3–5.6) (Table 3). Observed associations with marriage, education, personal history of incarceration, and binge alcohol use could apparently be explained by other variables and were eliminated from the final model. When lifetime number of partners number was categorized and included in the model, this variable was retained in the final model (odds ratio 1.3, 95% CI: 1.1–1.5) and gender was eliminated. Associations for other variables were essentially unchanged (not shown).
This study of North Carolina African Americans with newly reported heterosexually acquired HIV is to our knowledge the first such report in a largely rural African American population. Rates of sexual partner change and concurrent partnerships—both key determinants of HIV population transmission dynamics 15 —were high. During the year before the interview, more than half of respondents had multiple partners and nearly as many (40%) had concurrent partnerships. Almost all respondents believed it likely that at least 1 of their last 3 partners had had sex with others during the course of their relationship with the respondent. These findings suggest the presence of highly interconnected networks with potential for rapid propagation of HIV and other STIs.
Concurrency rates in this population during the previous 5 years (60%) were higher than among blacks randomly selected from rural North Carolina's general population (38%), 16 which in turn were higher than among black women in the US general population (21%). 3 Comparisons with other studies are more difficult because of differing methodology. Among sexually active men and women aged 18–39 years in Seattle, 22% reported a concurrent partner during their most recent partnership. 17 Fifteen percent of co-habiting or married men in Mexico City reported sex outside their main relationship during the preceding year. 18 More than 15% of individuals in the southeastern and southwestern United States in whom early syphilis had been diagnosed had had concurrent partnerships during the previous 4 weeks. 19
In multivariate analysis, concurrency was associated with male sex, an association that has been noted in other studies. 20,16 Younger African Americans with heterosexually transmitted HIV, as younger women in the US general population, 3 were more likely to report concurrency than those who were older.
Reflecting crack cocaine's extensive inroads into the southeastern United States, 21,22 >30% of respondents in our study reported crack use within the preceding 10 years. Crack's role in exchange of sex for drugs or money has been well documented 23; trading sex (“survival sex”) 20 may well explain the observed association between crack use and concurrency. Crack use, even after adjustment for partner number, was strongly associated with concurrent partnerships.
Incarceration of a partner was associated with greater prevalence of concurrency, an association that was also observed among young adults in Seattle. 17 While incarceration may be a marker for sexual risk behaviors, it can also promote concurrency by temporarily removing a partner from the relationship. A qualitative study of concurrent partnerships among adults described “separational” concurrency among persons with partners who were frequently incarcerated. 20
Strengths of this study include the focus on an understudied, largely rural population with relatively high heterosexual transmission and use of a carefully pretested questionnaire administered by trained interviewers who were from the same ethnic and cultural group as participants. Limitations include the relatively small sample size, a consequence of the high cost of conducting household interviews in a rural population, and the high refusal rate that is readily understandable for people who have recently learned that they are infected with HIV. Despite the 50% refusal rate, these results nevertheless represent the behavior of at least half of people with newly reported, heterosexually transmitted HIV infection in the target population. Even under the extreme assumption that all of the cases who refused did not have concurrent partnerships, the overall 5-year prevalence of concurrency would be 30%.
As all studies that depend on self-report data, misreporting is a possibility, though the usual expectation is that respondents will conceal socially proscribed behavior. Recall of partnership dates is a cognitively difficult task, 24 but the substantial concordance with the respondent's own acknowledgment of having had concurrent partnerships suggests that recall was adequate to identify concurrency. The interviewer's use of life history milestones relevant to the respondent should have improved the recall of dates, and our missing data rates were low except for income. Readers should bear in mind that for a common outcome such as concurrency in this population, the odds ratio for a given association is farther from 1.0 than is the prevalence ratio.
Social context influences sexual behavior and risk of STIs. 25,2 The physical and social circumstances associated with impoverishment—a striking feature of this study population—hamper individually oriented behavioral risk reduction approaches and likely promote risk behavior, 26 because personal agency in situations of oppression is limited. 27 Focus groups revealed pervasive economic and racial oppression in the African American population in the study area and perceived scarcity of black men because of their high incarceration rates and mortality. 28 These factors promote patterns of sexual behavior that transmit HIV and other STIs. Indeed, focus group respondents believed the paucity of men along with other structural factors, including poverty and lack of recreational outlets, was partly responsible for the concurrent partnerships they perceived as widespread among unmarried individuals.
In summary, a large proportion of HIV-infected African Americans in this study participated in concurrent partnerships and also believed that their partners had had sexual relationships with others during their relationship with the respondents. In 2000, the Centers for Disease Control adopted a new emphasis on persons with HIV as a strategy (Serostatus Approach to Fighting the HIV Epidemic, SAFE) for controlling the HIV epidemic. 29 Our data support the importance of prompt identification and effective intervention for HIV-infected individuals, a substantial subset of whom are likely major generators of new HIV infections. However, individually oriented approaches alone will likely be inadequate to deal with the interconnected problems of inadequate economic resources, social inequity, racial oppression, and sexual networks conducive to propagation of HIV.
The authors thank Drs. Amy Lansky and Joanne Earp for their assistance with questionnaire development; Ms. Evelyn Faust, Ms. Judy Owen-O'Dowd, and the NC HIV-STD Control Section and Disease Intervention Specialists for their assistance with recruitment; Drs. Sevgi Aral, Ward Cates, and Greg Samsa for their insightful comments; Ms. Merritha Williams and Stephanie Betran for recruiting and interviewing the respondents; and the respondents for their participation in this research.
1. Centers for Disease Control and Prevention. HIV/AIDS Surveillance Rep. 2001:1–33.
2. Adimora AA, Schoenbach VJ. Contextual factors and the black-white disparity in heterosexual HIV transmission. Epidemiology. 2002; 13:707–712.
3. Adimora A, Schoenbach V, Bonas D, et al. Concurrent sexual partnerships among women in the United States. Epidemiology. 2002; 13:320–327.
4. Klovdahl AS, Potterat JJ, Woodhouse DE, et al. Social networks and infectious disease: the Colorado Springs study. Soc Sci Med. 1994; 38:79–88.
5. Friedman SR, Aral S. Social networks, risk-potential networks, health, and disease. J Urban Health. 2001; 78:411–418.
6. Ghani AC, Swinton J, Garnett GP. The role of sexual partnership networks in the epidemiology of gonorrhea. Sex Transm Dis. 1997; 24:45–56.
7. Rothenberg R, Narramore J. The relevance of social network concepts to sexually transmitted disease control. Sex Transm Dis. 1996; 23:24–29.
8. Garnett GP, Hughes JP, Anderson RM, et al. Sexual mixing patterns of patients attending sexually transmitted diseases clinics. Sex Transm Dis. 1996; 23:248–257.
9. Rothenberg RB, Sterk C, Toomey KE, et al. Using social network and ethnographic tools to evaluate syphilis transmission. Sex Transm Dis. 1998; 25:154–160.
10. Aral SO, Hughes J, Stoner B, et al. Sexual mixing patterns in the spread of gonococcal and chlamydial infections. Am J Public Health. 1999; 89:825–833.
11. Aral SO. Sexual network patterns as determinants of STD rates: paradigm shift in the behavioral epidemiology of STDs made visible. Sex Transm Dis. 1999; 26:262–264.
12. Anderson R, Gupta S, Ng W. The significance of sexual partner contact networks for the transmission dynamics of HIV. J Acquir Immune Defic Syndr. 1990; 3:417–429.
13. Laumann EO, Youm Y. Racial/ethnic group differences in the prevalence of sexually transmitted diseases in the United States: a network explanation. Sex Transm Dis. 1999; 26:250–261.
14. Morris M, Kretzschmar M. Concurrent partnerships and transmission dynamics in networks. Soc Networks. 1995; 17:299–318.
15. Anderson RM. Transmission dynamics of sexually transmitted infections. In:Sexually Transmitted Diseases
, 3rd ed. Edited by Holmes KK, Mardh PA, Sparling PF, et al. New York: McGraw-Hill; 1999.
16. Adimora AA, Schoenbach VJ, Martinson FEA, et al. Concurrent sexual partnerships among African Americans in the rural South. Ann Epidemiol. (in press)
17. Manhart LE, Aral SO, Holmes KK, et al. Sex partner concurrency: measurement, prevalence, and correlates among urban 18–39-year-olds. Sex Transm Dis. 2002; 29:133–143.
18. Pulerwitz J, Izazola-Licea J-A, Gortmaker S. Extrarelational sex among Mexican men and their partners' risk of HIV and other sexually transmitted diseases. Am J Public Health. 2001; 91:1650–1652.
19. Koumans E, Farley T, Gibson J, et al. Characteristics of persons with syphilis in areas of persisting syphilis in the United States: sustained transmission associated with concurrent partnerships. Sex Transm Dis. 2001; 28:497–503.
20. Gorbach PM, Stoner BP, Aral SO, et al. “It takes a village”: understanding concurrent sexual partnerships in Seattle, Washington. Sex Transm Dis. 2002; 29:453–462.
21. Berry DE. The emerging epidemiology of rural AIDS. J Rural Health. 1993; 9:293–304.
22. Thomas JC, Schoenbach VJ, Weiner DH, et al. Rural gonorrhea in the southeastern United States: a neglected epidemic? Am J Epidemiol. 1996; 143:269–277.
23. Schwarcz SK, Bolan GA, Fullilove M, et al. Crack cocaine and the exchange of sex for money or drugs: risk factors for gonorrhea among black adolescents in San Francisco. Sex Transm Dis. 1992; 19:7–13.
24. Warnecke RB, Sudman S, Johnson TP, et al. Cognitive aspects of recalling and reporting health-related events: Papanicolaou smears, clinical breast examinations, and mammograms. Am J Epidemiol. 1997; 146:982–992.
25. O'Reilly KR, Piot P. International perspectives on individual and community approaches to the prevention of sexually transmitted disease and human immunodeficiency virus infection. J Infect Dis. 1996; 174:S214–S222.
26. Krueger LE, Wood RW, Diehr PH, et al. Poverty and HIV seropositivity: the poor are more likely to be infected. AIDS. 1990; 4:811–814.
27. Farmer P. Infections and Inequalities: The Modern Plagues.
Berkeley and Los Angeles, CA: University of California Press; 1999.
28. Adimora AA, Schoenbach VJ, Martinson FE, et al. Social context of sexual relationships among rural African Americans. Sex Transm Dis. 2001; 28:69–76.
29. Janssen RS, Holtgrave DR, Valdiserri RO, et al. The serostatus approach to fighting the HIV epidemic: prevention strategies for infected individuals. Am J Public Health. 2001; 91:1019–1024.
Copyright © 2003 Wolters Kluwer Health, Inc. All rights reserved.