The publisher's final edited version of this article is available at J Adolesc Health See other articles in PMC that cite the published article. Abstract Purpose Evaluate whether adolescent women who received economic benefits from their boyfriends were more likely never to use condoms.
Methods Data is from a longitudinal HIV prevention intervention study with African-American adolescent women in urban Atlanta surveyed at baseline, 6 months, and 12 months. The primary outcome was never using condoms in the past 14 and 60 days at 6 and 12 months. The primary predictor was having a boyfriend as primary spending money source at baseline. Analysis minimized confounding using propensity weighting to balance respondents on 81 variables. After propensity score weighting, no statistically significant differences for 81 evaluated covariates remained, including age distributions.
Women whose boyfriend had been their primary spending money source but found another spending money source were more likely to start using condoms than women who continued. Women whose boyfriends owned cars were more likely never to use condoms. Implications and Contribution Disadvantaged teenage women who receive spending money from their boyfriends may not explicitly trade unsafe sex for money but are nonetheless more likely to have unsafe sex.
Women with less relationship bargaining power, and hence limited ability to insist on safe sex, are particularly at risk of condom non-use 3. We hypothesize that adolescent females whose boyfriend is their primary source of spending money or whose boyfriend owns a car are more likely never to use condoms. Some disadvantaged women receive material benefits from their committed relationship partners and may thus be at risk for low dyadic power. Explicitly transactional sex — sex traded directly for money or drugs — is a known risk factor for risky sex 5.
Few studies in US populations have investigated long-standing relationships where the economic dimension is implicit rather than explicit 6. Some African women receiving economic benefits from their relationships describe coercion in sexual relationships as normal Other women claim to avoid partner coercion and describe economic benefits as empowering economic opportunities 13 , Conversely, African women who are economically empowered relative to their partners have greater bargaining power 15 , higher condom use 16 , 17 , and lower HIV risk 18 , Relationship power differentials have been identified as a factor in HIV spread in Africa 6 , 20 , and several interventions in Africa have succeeded in increasing stigma for intergenerational and power-disparate sexual relationships These issues have not been studied extensively in the US.
Based on the research from southern Africa, we hypothesize that disadvantaged adolescent women whose boyfriends are their primary source of spending money are more likely never to use condoms than women who receive spending money from other sources.
This research tests hypotheses that teen women who receive spending money from their boyfriends are more likely never to use condoms and to not respond to an effective safe-sex intervention. Among women whose initial primary source of spending money was their boyfriend, we also test a hypothesis that women who change to another primary source of spending money are more likely to start using condoms than if their boyfriend continues to be their primary source of spending money.
A car is a large investment, particularly for urban adolescents, so this research also tests the hypothesis that female adolescents whose boyfriends own a car are more likely never to use condoms. This research is unique for using propensity score weighting to minimize confounding. Methods Theoretical models This study is guided by the theories of money and commodities by Lee Rainwater and Michael Walzer who hypothesized that full membership in modern industrial societies requires deploying money for consumer goods beyond the level of subsistence 22 , Relationship partners receive decision-making precedence proportional to the resources that they bring to their relationships, according to theories of sociology of the family 4.
Together, these theories predict that boyfriends who own cars or give spending money to their girlfriends will have greater power within relationships, and some boyfriends will use that power to promote condom non-use.
Data We evaluated these hypotheses using data from the study of Horizons, an HIV prevention intervention for African-American females in urban Atlanta.
Unmarried African-American females were eligible to participate if they were sexually active in the past 60 days and neither pregnant nor attempting pregnancy: At baseline, 4 of the participants had children whom they lived with.
At each of the three waves, a minute interview was administered via audio computer-assisted subject interviewing, and participants were tested for chlamydia, gonorrhea, and trichomoniasis using nucleic-acid-based metrics. Condom non-use was measured with 3 questions for the past 14 and 60 days: We compared women who responded that their boyfriend was their primary source of spending money with women who selected any of the other sources of spending money. Propensity score weighting motivation Matched sampling is a nonparametric method for reducing confounding by comparing a set of respondents with a characteristic with similar respondents who lack that characteristic.
The respondents with the characteristic are analogous to the treatment group in a randomized experiment, and the respondents without the characteristic are analogous to the control group. Women whose boyfriends are their primary source of spending money may differ from women with other spending money sources, potentially confounding any associations between condom non-use and receiving spending money.
Regression analysis attempts to reduce confounding but relies on assumptions that are rarely satisfied, so confounding remains after regression analysis 25 , Several matched sampling methods could minimize confounding. This study uses propensity score weighting because it preserves sample size and thus power better than other matched sampling methods After weighting, the only observable difference between groups will be the source of spending money.
Formulation of propensity score models The predictors in the propensity model are potential confounders of the relationship between spending money source and never using condoms at 6 and 12 months 28 , including never using condoms at baseline.
A second propensity score model was formulated among the women whose boyfriends were their primary spending money source at baseline, to predict which women would discontinue having their boyfriend as their primary spending money source at 6 months.
A third propensity model was formulated to predict which women are likely to have at 6 months a boyfriend who owns a car, and likewise predicting propensity to have a boyfriend at 12 months who owns a car.
Potential confounders Factors are considered potential confounders in this study if they satisfy two criteria: We describe potential confounders, how they may confound the relationship between spending money source and condom use, and why the two groups must be balanced on these factors. Irrespective of parent socioeconomic status, adolescent women with greater human and financial capital measured by last grade completed in school, employment status, and high school graduation may be less likely to receive money from boyfriends and more likely to use condoms.
Women with greater potential relationship inequality may be more likely to receive money from boyfriends and less likely to use condoms 3. Related potential confounders include baseline condom non-use and history of abuse or forced sex; greater potential relationship inequalities, such as greater age difference with boyfriend; more permissive sexual norms, such as more lifetime partners; and risk-taking propensity indicated by cigarette and marijuana use. Limiting the analysis to the region of common support excluded 20 control respondents who were predicted less likely to receive money from their boyfriends than respondents within the treatment group.
These 20 control respondents had estimated propensity scores lower than the minimum estimated propensity score among the treated. One treated subject was predicted to be more likely to receive money from her boyfriend than any subjects within the control group, so was likewise excluded. The remaining respondents whose boyfriends were their primary sources of spending money were given a weight of 1. A parallel process was used to implement the other 3 propensity weighting models.
Distributions of each variable were compared before and after propensity score weighting using the Pearson chi-squared test.
The cumulative distributions of age, boyfriend age, and age difference with boyfriend were compared with the chi-squared test to ensure that the groups did not differ in distribution Table 1.
Table 1 Background characteristics at baseline, comparing women whose boyfriend is her primary source of spending money at baseline with women whose spending money at baseline comes from another source, before and after propensity score weighting. Factors are sorted within category in order of p-value prior to matching. Age differences may affect power between women and their boyfriends, so ages are compared both in cumulative distribution and in mean.
All factors measured at baseline Before weighting.