Condom use among high-risk heterosexual women with concurrent sexual partnerships,Houston,Texas,USA

INTRODUCTION

Concurrency is a sexual network pattern that occurs when an individual has two or more sexual partnerships that overlap in time. Concurrent partnerships increase the likelihood of exposure to infected persons and reduce the time between sexual contacts, ¹ thus allowing enhanced transmission of sexually transmitted infections (STIs) without the delay afforded by sequentially monogamous partnerships. ²

Condom use dynamics in the context of concurrent sexual partnerships may be an important factor for transmission of HIV. There is evidence that individuals use condoms in higher risk sexual partnerships; consequently, individuals are more likely to have ‘safe sex’ with ‘risky’ partners and ‘risky sex’ with partners who are perceived as ‘safe’. ³ Condom use is more likely in casual and recently formed partnerships. ⁴ Research among adolescents suggests that the prevalence of condom use significantly declines within the first three weeks after new partnership formation. ⁵ In addition, older individuals are less likely to use condoms than younger individuals. Condom use is also less likely when drugs and/or alcohol are involved in the sexual encounter. ⁶

Among individuals with multiple sex partners, condoms may be used in some partnerships but not others. Risky sexual behaviours with one partner may thus lead to the transmission of an STI throughout the sexual network. The purpose of this study is to describe the frequency of concurrency among high-risk heterosexual women in Houston, Texas and determine the factors associated with condom use in this context.

METHODS

We analysed data from the Houston site of the National HIV Behavioral Surveillance (NHBS) programme. NHBS aims to assess the prevalence and trends in HIV risk and testing behaviours among persons at high risk for infection, including high-risk heterosexuals. High-risk heterosexuals in this study are adult men and women who have a physical or social connection to high-risk areas, which are defined by high rates of poverty and high rates of HIV infection (Figure 1). ⁷

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Figure 1

High-risk areas of Houston, Texas, USA

High-risk areas were described using poverty ⁸ and HIV surveillance data. ⁹ An index of risk was developed using poverty and HIV rates. Of 895 census tracts, 133 were identified as high-risk areas. High-risk heterosexuals were recruited from within these areas using respondent-driven sampling and completed the survey at one of three field sites.

Data were collected between November 2006 and June 2007. Individuals were eligible to participate if they were between 18 and 50 years of age, reported having heterosexual vaginal or anal sex within the past 12 months, and had not participated in this study previously. ⁷ Interviewed participants who reported living in a target census tract were invited to recruit peers using study coupons, and received compensation for both study participation and peer recruitment (maximum of three). The study was approved by The University of Texas Committee for the Protection of Human Subjects and participants provided verbal informed consent. Eligible and consenting participants were interviewed face-to-face by trained staff who used hand-held computers to record answers.

RESULTS

A total of 938 eligible and consenting participants completed the survey. Of these, 12 were excluded because they were homosexual or transgender and 36 were excluded because they had injected drugs in the past 12 months. Of the 553 females in the sample, 256 (49%) were identified as having a concurrent partnership at the time of their last heterosexual encounter.

Table 1 presents sample demographics and risk behaviours. The sample consisted predominately of low income African Americans with low levels of education and employment. The mean and median number of total sexual partners in the past 12 months was 6.4 and three, respectively. Eighty-eight percent of participants reported having a main partner in the past 12 months (mean number of main partners 1.5, median 1), 76% reported a casual partner (mean 3.2, median 2), and 28% reported an exchange partner (mean 7.6, median 2).

The density of condom use is shown in Figure 2. Condom use at last sexual encounter was reported by 67 participants (26%). Among those who used a condom at their last vaginal sexual encounter, 9% reported that the purpose of condom use was prevention of pregnancy; 26% reported prevention of HIV and/or other STDs; and 64% reported both. Of those who did not use condoms, 45% used an alternative birth control method (oral contraceptives, tubal ligation, rhythm, or withdrawal).

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Figure 2

Density of condom use among women with concurrent partners in Houston, Texas, USA

Table 2 presents the unadjusted and adjusted odds ratios (ORs) of condom use at last sexual encounter by associated factors. Among this sample of women with concurrent partnerships, 77% reported that their last sexual encounter was with a main partner. None of the 72 participants who reported having exchange partners in the past 12 months had their most recent sexual encounter with an exchange partner and thus this category was not included in the analysis. The adjusted odds of condom use were six times greater with a casual partner compared with a main partner.

Concerning the participant's perceptions of whether their partner was sexually involved with someone else during the duration of their relationship, 6% of participants reported that their partner ‘definitely did not’ have sex with someone else, 18% reported ‘probably did not,’ 35% reported ‘probably did’ and 41% reported ‘definitely did.’ Compared with women who perceived that their partner definitely was concurrently involved, those who believed that their partner definitely was not were significantly more like to use a condom (OR = 18.9), after adjusting for other variables in the model. Women who believed that their partner probably did and probably did not were respectively 1.9 and 1.4 times more likely to have used a condom at their last sexual encounter, although these estimates did not reach statistical significance.

Among the four categories of perceived partner concurrency, there were significant differences with regard to partner type (F = 6.0, P < 0.01). A test of multiple comparisons revealed that women who perceived that their partner definitely did have a concurrent partnership were significantly more likely to report last sex with a main partner compared with women who perceived that their partner definitely did not (P = 0.04). There were no significant differences among the four categories concerning reason for condom use (F = 0.8, P = 0.48) or knowledge of partner's HIV status (F  =  2.1, P = 0.10).

A second multivariate logistic regression model was constructed to determine whether estimates significantly changed after excluding the women who perceived that their partner definitely did not have a concurrent partnership. All estimates remained stable (data not shown).

DISCUSSION

The prevalence of concurrent partnerships in the study population was high. Almost half of the participants reported having a concurrent partnership during their relationship with their last sexual partner. Over three-quarters of participants believed that their last partner had sex with someone else during the duration of the partnership. The high levels of self-reported and perceived partner concurrency suggest the presence of a dense sexual network, potentially enabling the rapid spread of STIs and HIV.

Condom use among this sample of heterosexual females with concurrent sexual partnerships was low, with under a quarter of participants reporting that a condom was used during their last sexual encounter. Condom use was significantly more likely among casual partnerships and partnerships in which drugs and/or alcohol were not used during sex. Our data also suggest that condom use was less likely in partnerships in which the woman perceived that her partner was involved in another relationship. Due to our small sample size, however, we were unable to assess the magnitude of this association. Additionally, the quantitative nature of our study limited its ability to examine underlying factors which may promote concurrency and lack of condom use.

Among the women who used condoms, the majority did so to protect against both pregnancy and HIV/STDs. Just under half of those who did not use condoms reported that they used an alternative method of birth control. This suggests that, while many women may take protective measures to avoid pregnancy, sexual safety behaviours aimed at protection against HIV and STIs are significantly lacking. This is especially disconcerting given that the rate of HIV in high-risk census tracts of Houston ranges from 70 to 1020 per 100,000 persons. ⁹

This research was conducted within a population living in extreme poverty, with over half of participants reporting annual incomes under $5000 and over 70% reporting current unemployment. This extreme poverty and lack of economic opportunity may support sexual networks involving concurrent partnerships. ² The high frequency of concurrent partnerships is of concern due to the capacity of concurrency to amplify the rate of spread of HIV. ¹¹ Whereas in sequential monogamy, the acute period of high HIV infectivity may elapse during the gap between dissolution of one partnership and formation of the next, concurrency acts as a ‘temporal’ bridge that increases the risk of HIV transmission. Additionally, the risk of transmission is increased due to the general infrequency of condom use. Our data suggest that qualitative data in conjunction with surveillance data are urgently needed to provide an understanding of the context surrounding concurrency and condom use among high-risk heterosexual women. A more in-depth understanding of these behavioural and social dynamics would greatly benefit HIV intervention efforts that target high-risk heterosexuals.