When used correctly and consistently, the male latex condom is a powerful barrier against the spread of sexually transmitted disease (STD) and HIV . Since the 1970s, the prophylactic efficacy of the male condom against a variety of microorganisms has been evaluated in cross-sectional, case-control, and follow-up studies [2–18].
Three recent large-scale trials have demonstrated that it is possible to reduce the incidence of STD and HIV in high-risk groups through structured behavioral interventions that include consistent condom use as a central component of safer sexual behavior [19–21].
Although male condoms are widely available, effective, and a recognized means of preventing STD and HIV, many at-risk women still fail to achieve consistent protection against STD. The use characteristics of the male condom and the social norms associated with male condom use are thought to create a dynamic in which the male partner has a disproportionate amount of control over the decision of whether or not to use the product. This situation has prompted the call for safe and reliable female-controlled methods of STD and HIV prevention [22–25]. Approved for sale by the Food and Drug Administration in 1992, the female condom has been described as the best female-controlled prophylactic to come onto the market . The modest body of information available about the efficacy of the female condom indicates that it may provide a viable alternative to the male condom [26–31].
Although the availability of options such as the female condom may improve the gender dynamics of condom-use behavior, it is likely that interaction within partnerships will continue to play an important role in the decision to use barrier contraceptives and in the ability of a couple to maintain consistent use over time. Condom use appears to vary systematically according to the type of sexual partnership. Cross-sectional examinations of monogamous heterosexuals reveal that the willingness to propose and the ability to achieve condom use are greater within new and casual relationships than within long-term or primary relationships [32–38]. Surveys of a variety of population groups ranging from college students to commercial sex workers, and including representative samples of European and United States populations, have evaluated condom use by partner type [37,39–48]. These studies systematically show that consistent condom use is reported more frequently with casual or new partners than with primary partners. It has also been hypothesized that as sexual relationships grow more stable and intimate over time, condom use decreases . With the exception of one longitudinal study of commercial sex workers in Cameroon , however, most of the evidence available is based on retrospective recall rather than on prospective recording of condom use. Furthermore, we are not aware of any study of the longitudinal changes of condom use within relationships as the nature of the relationship changes (e.g., from a new partnership to a primary partnership).
The purpose of the present study was to examine the association between partner type and condom use in a group of women of childbearing age who were at risk of STD and HIV infection. Unlike previous studies, which relied on the retrospective recall of condom-use behavior, this study used detailed prospective diary reports of sexual behavior and condom use over a 6-month period. Thus, it was possible to investigate the association between partner type and condom use for each act of intercourse during follow up for the entire study group and within the subgroup of women who had intercourse with multiple partners. It was also possible to evaluate the influence of partner type on condom-use consistency during months in which women encountered multiple partners, and within couples that experienced a relationship status change during the follow-up period.
Materials and methods
Study design and procedures
Data for this study come from a prospective follow-up investigation of the prophylactic efficacy of the female condom. All participants were women recruited from two urban STD clinics in Alabama between 14 July 1995 and 28 February 1998. Approximately 30 000 men and women visit the two clinics each year to receive STD diagnosis and treatment. Five eligibility criteria were employed to recruit participants. Eligible individuals were required to be between 18 and 35 years of age, not to be currently pregnant or planning to become pregnant in the next 6 months, not to have had a hysterectomy, not to be taking antibiotics on a regular basis, and to have no plans to be out of town for any prolonged duration during the 6-month follow-up period. Women meeting these criteria who agreed to participate were scheduled to return approximately 10 days later for an initial study visit.
At the initial study visit, women provided written informed consent, were interviewed by female research assistants, received an intensive behavioral intervention promoting barrier contraception and female condom use, and were taught to complete a detailed sexual diary. A licensed nurse-clinician or nurse practitioner performed a pelvic examination on each woman and collected physical specimens following health department guidelines. The nurse also assessed each woman's ability to insert the female condom correctly. Upon completion of the physical examination, women were provided with a free 6-week supply of male and female condoms and compensated $25.
Participants returned at monthly intervals until they either completed six visits or withdrew from the study. At each follow-up visit, a series of questions was asked in order to assess whether individuals continued to meet eligibility criteria and to record general information about sexual activity and contraceptive behavior since the previous visit. Sexual diaries were also returned at each follow-up visit for data abstraction and coding; diaries were reviewed with research assistants to verify the completeness and accuracy of the information reported. Participants were re-examined at each visit and received additional supplies of male and female condoms as needed. Women were compensated $25 for each follow-up visit attended and $50 upon completion of the study.
Of importance for this analysis is the sexual diary, which was designed to gather information on sexual activity and barrier use during each month of follow-up. Each participant was instructed to use the diary for taking personal notes in addition to recording sexual activity, male and female condom use, the initials of sexual partners, and partner type. Partner type consisted of three categories: new, regular, and casual. A new partner was a partner first encountered during that month. A regular partner was a partner she had met before the current month with whom she had an established relationship, such as her husband or boyfriend. A casual partner was a partner she had met before the current month but whom she did not consider as regular.
The analytic plan consisted of four components. First, the association between condom use and partner type was evaluated for every act of vaginal intercourse reported during the 6-month follow-up period. Second, the association between condom use and partner type was evaluated for every act of intercourse reported by the subgroup of women who encountered multiple partners during follow-up. Third, condom-use consistency was assessed by partner type during all months in which women encountered multiple partners of different types. Fourth, changes in condom-use consistency were evaluated within couples that experienced a transition in relationship status during the follow-up period (i.e., a partner who was classified into two different categories in different months of follow-up, such as a new partner who became regular, or a regular partner who became casual).
Logistic regression models for repeated measurements were used to assess the association between partner type and condom use for the entire study group and for those who encountered multiple partners. Because two condom types were used in the study, two nested analyses were conducted. The first logistic regression analysis examined the association between partner type and the use of any condom (i.e., either male or female condom use) at each act. The second logistic regression analysis examined the association between partner type and the specific condom used, conditional on having used a condom (i.e., restricted to acts in which either the female or the male condom was used). The possible correlation of outcomes within subjects was assumed to be autoregressive of order 1 and was taken into account using generalized estimating equations . Baseline characteristics of the woman (age, race, marital status, education, employment status, income, age at sexual debut, number of lifetime sexual partners, pregnancy history, STD history, STD diagnosis at baseline) were considered as potential confounders of the association between partner type and condom use and were included in the models.
To further clarify whether the behavior of the same woman varied systematically with the type of partner, we examined condom-use consistency (i.e., use of the male or female condom during each act of vaginal intercourse) by partner type during each month in which a woman encountered multiple partners. The partner initials and corresponding partner classification reported in the sexual diary were used to identify the number and type of partners encountered during each month of follow-up. Consideration was given to the possibility that women might encounter partners with the same initials. In such instances, participants were instructed to provide unique initials for each partner. Condom-use consistency within the follow-up interval was calculated separately by partner type for each woman, and follow-up intervals were classified according to whether consistent condom use was achieved with each partner type encountered. Conditional logistic regression was used to assess the influence of partner type on condom use, taking into account the potential correlation among repeated measures (i.e., multiple months of follow-up in which the same woman encountered different types of partner). Control of confounding was obtained implicitly, since the conditional logistic regression analysis evaluated effects within months of follow up of the same woman.
The final analysis evaluated condom use within couples that experienced a relationship status change during the study. The partner type associated with a set of initials during one month was compared with the partner type associated with the same set of initials in other months to determine partner status changes during the follow-up interval. Consistency of condom use was calculated for each relationship before and after the relationship status change and was evaluated using conditional logistic regression models similar to those used in the analysis of condom-use consistency among women who encountered multiple partners during one month.
A total of 3531 potentially eligible women received recruitment interviews, 2702 women (77%) agreed to participate, and 1159 women (33%) attended the initial visit. Of the 1159 women who attended the initial visit, 869 (75%) came to at least one follow-up visit, returned at least one sexual diary, and reported at least one act of vaginal intercourse during the follow-up period. All six follow-up visits were attended by 525 women (45%). The mean number of visits attended by a woman was four. Regression analyses comparing study participants with women who refused to participate indicated that the refusers were slightly older, less often African-American, more educated, had fewer lifetime partners, less often had a history of STD, and were more often hormonal contraceptive users (data not shown). Women who agreed to participate but did not attend the initial visit were not significantly different from study participants.
The 869 women who returned for follow-up were typically young, African-American and of low socioeconomic status. The mean age of participants was 24 years. The racial/ethnic distribution of the group was 85% African-American, and 15% non-African-American. Seventy-five percent reported being single and 22% were living with a male sexual partner. On average, participants had completed 12 years of formal education and 56% were employed at the time of recruitment. Monthly income from all sources was for the most part low: 39% made less than $300, 29% made between $301 and $600, and 32% made over $600. All participants stated that they did not plan to become pregnant during the 6-month observation period and renewed their statement at each follow-up visit as a condition for continued eligibility. In fact, a majority used a method of birth control: 20% of the initial study group was surgically sterilized, 30% used hormonal methods of contraception, and 50% (non-mutually exclusive with previous choices) used condoms. Only 17% stated that they did not use any form of birth control. Participants were at high risk of contracting an STD. The mean age of sexual debut was 16 years, and the mean number of lifetime sexual partners was 7.5. Two thirds (68%) reported having had a past STD. At entry into the study, 55% were diagnosed with an STD. The judgment that the group was at high risk for STD was also based on the knowledge that approximately 25% of the STD clinic patients return to the clinic with a new complaint within 6 months.
Condom use by partner type
During the 6-month follow-up interval, 865 (99%) participants reported having intercourse with a regular partner, 284 (33%) encountered a casual partner, and 235 (27%) encountered a new partner. A total of 29 312 acts of vaginal intercourse were reported during the study. The male condom was used in 42% of these acts and the female condom in 27%. No barrier was used in 31% (Table 1). In a logistic regression model evaluating use of any condom as the outcome of each act of intercourse, the probability of using a condom was significantly higher with new partners [odds ratio (OR) 1.7; 95% confidence interval (CI) 1.3–2.2] and casual partners (OR 1.6; 95% CI 1.3–2.1) than with regular partners. In the same model, non-African-American women (OR 0.6; 95% CI 0.4–0.9) and women who reported engaging in intercourse before age 16 years (OR 0.6; 95% CI 0.4–0.9) were less likely to use condoms. In a logistic regression model evaluating use of the female condom as the outcome of each protected act of intercourse, the probability of using the female condom was lower with new (OR 0.5; 95% CI 0.4–0.6) and casual partners (OR 0.4; 95% CI 0.4–0.6) than with regular partners. In the same model, women who were 25 years or younger were significantly less likely to use the female condom (18–20 years of age OR 0.7; 95% CI 0.5–0.9; 21–25 years of age OR 0.8; 95% CI 0.7–0.9) than women who were 26 years or older. Non-African-American women were more likely to use a female condom than African-American women (OR 1.5; 95% CI 1.1–2.1).
Condom use by partner type among women who encountered multiple partners
The aggregate data presented above represent a comparison among subgroups of women who were heterogeneous with respect to the type of partner encountered during the follow-up interval. For example, the rate of male condom use with a regular partner reported in Table 1 is calculated on the basis of a large number of women who had sex with only one partner during the study. By contrast, the rate of male condom use among women who encountered a new partner is calculated primarily on the basis of the experience of women who changed partners during the study. The observed difference in condom-use consistency by partner type could result, therefore, from confounding by characteristics of the woman, rather than from the type of partner.
Intercourse with multiple partners during the study was reported by 461 women (51%), and accounted for 15 549 (53%) of the 29 312 reported acts of vaginal intercourse. The pattern of barrier use in this subgroup of women was similar to that of the entire study group (Table 2). Throughout the follow-up period, women who encountered multiple partners used condoms more frequently with new (OR 1.6; 95% CI 1.2–2.1) and casual (OR 1.5; 95% CI 1.1–1.9) partners than with regular partners. Female condom use was again less frequent with new (OR 0.5; 95% CI 0.4–0.6) and casual (OR 0.5; 95% CI 0.4–0.6) partners than with regular partners.
Condom-use consistency during months in which multiple partners were encountered
Women had intercourse with multiple partners of different type during a total of 639 months of follow-up. Both a new and a regular partner were encountered during 189 months, a new and a casual partner during 117 months, and a casual and a regular partner during 333 months (Table 3). For those women who encountered new and regular partners, condom-use practices were concordant (i.e., condoms were used consistently with both partner types or inconsistently with both partner types) during 113 follow-up intervals. Condom use was consistent with the new partner and inconsistent with the regular partner during 55 intervals, and the reverse was true during the remaining 21 intervals. Condom use was, therefore, less consistent with regular partners than with new partners within the same month (P < 0.001). Similarly, during the 333 months in which a woman encountered a casual and a regular partner, condom use was systematically less consistent with the regular partner than with the casual partner (P < 0.001). In contrast, there was no significant difference in condom use consistency by partner type when a woman encountered both a new and a casual partner during the same month.
In this analysis, the female condom appeared to be an important means of achieving consistent protection with a regular partner. In the 65 months of follow-up during which a woman achieved consistent use both with a new partner and with a regular partner, the proportion of the acts of intercourse protected by the female condom was 26% with a new partner and 33% with a regular partner. In the months of follow-up in which consistent protection was achieved only with the new partner, the proportion of acts of intercourse protected by the female condom was 14%, while in the months of follow-up in which consistency was achieved only with the regular partner, the proportion of acts protected by the female condom was 24%. Women also used the female condom more often with a regular partner and more often to achieve consistent protection with a regular partner in months in which a woman encountered both a regular and a casual partner. Finally, women used the female condom more often with a casual partner and more often to achieve consistent protection with a casual partner, in months in which both a casual and a new partner were encountered (results not shown in detail).
Relationship status change and condom-use consistency
The study also offered a limited opportunity to examine changes in condom-use consistency following transitions in relationship status. There were four possible relationship status changes: from new to regular, from casual to regular, from new to casual, and from regular to casual. Twenty eight relationships experienced a counterintuitive status change (e.g., regular to new, casual to new) (n = 4) or shifted back and forth between casual and regular status from month to month (n = 24). These relationships were excluded from the analysis. Altogether, 185 relationship status changes occurred during follow-up: 121 women had one relationship that changed status, 19 women had two relationships that changed status, six women had three relationships that changed status, and two women had four relationships that changed status. Women who experienced clear relationship status changes with multiple partners (n = 27) were included in the analyses as many times as there were relationships that changed status during their follow-up.
In all, 49 relationships changed from new to regular, 47 changed from casual to regular, 37 changed from new to casual, and 52 changed from regular to casual. Although the number of discordant partnerships for each type of change in relationship status was small and the power of this analysis was limited, there was a clear and statistically significant excess of relationships in which consistency of use decreased after the relationship status changed from new to regular (P < 0.03) (Table 4). The data available for this analysis were too sparse to evaluate whether the likelihood of using the female condom changed with partnership status.
Our findings provide persuasive evidence that the type of sexual partnership plays an important role in determining consistency of condom use. The findings are compatible with the hypothesis that the greater the affective distance between partners the less frequently condoms are used . Women who were in regular partnerships were less likely to use condoms consistently than women who were in new or casual relationships, which presumably are less stable and intimate than regular partnerships. The findings also provide support for the notion that condom use decreases as a relationship grows more stable and intimate over time. In this study, as relationship status changed from new to regular a significant decrease in condom-use consistency was observed.
Female condom use was significantly less common with new and casual partners than with regular partners. This association was evident for the entire study group and remained strong when analysis was restricted to women who encountered multiple partners. Although consistent condom use was less frequent with a regular partner than with a new or casual partner, the female condom was used more often to achieve consistent protection with a regular partner and the male condom was used more often to achieve consistent protection with a new or casual partner. It is possible, therefore, that the difference in overall protection by partner type would have been more extreme had the male condom been the only device promoted in this study. If this finding is confirmed, the female condom may provide an important supplement to the male condom for promoting barrier methods within regular partnerships.
Other explanations of the observed differences in condom use by partner type should be taken into consideration. Cultural, psychosocial, and contextual factors may also influence the decision about whether or not to use a condom with a particular type of partner. For example, cultural norms may encourage condom use for casual sex and within new relationships and discourage condom use within stable long-term relationships and marriage. Further, individual perceived need for condoms may vary by partner type based on the belief that there is less risk of STD or HIV infection with intimate and long-term monogamous partners than with new and casual partners. Finally, when sex is combined with drugs and alcohol, when there are large disparities in age between partners, and in the context of sexual coercion and paid sex, high-risk unprotected intercourse is more common . The information gathered in this study did not allow an analysis of the causal relation between these variables and consistency of condom use by partner type.
Several potential limitations should be kept in mind in interpreting the findings of this study. First, the study group was drawn from at-risk women attending two urban STD clinics in Alabama. Preliminary analyses suggest that women at higher risk of STD tended to select themselves into the study. Furthermore, a substantial proportion of the participants withdrew before completing follow-up. No major demographic or baseline differences existed between women who completed the study and women who withdrew. However, if withdrawal from follow-up occurred as a function of the characteristics of the partnership or condom-use consistency, the association described in this paper could be biased. Although selection bias weakens our ability to generalize to the entire population, the study group consisted of women whose risk profile is highly relevant for the study of STD and HIV epidemiology and represents an important target for public health interventions. Internal validity, rather than sample-to-population representativeness, is the basis for generalizing the associations found in this study to a larger population of women at high risk of STD. The amount and quality of data collected in this study, its prospective design, and the strength of the within-month and within-partnership analyses lead us to believe that important generalizations can be made from the results of this study.
Second, classification of partnerships was determined on the basis of the woman's subjective report. While a woman may have regarded a man as her regular partner, we have no way of determining whether she was regarded as his regular partner. Thus, differences in the way sexual partners classified their relationship may have had a bearing on the decision to use condoms. Although it is unlikely that participants did not accurately represent new partnerships, a woman could have incorrectly classified a partner as regular, while his perception was that the relationship was casual. As a result, the comparison between regular and casual partners may be biased, most likely toward the null.
Third, consistency of condom use increased sharply at entry into follow-up as a consequence of the behavioral intervention and declined gradually over the course of the study . The decrease in condom-use consistency observed among couples that changed status from new to regular may have resulted, in part, from the overall decline in condom use observed in the cohort at large. This interpretation of the findings is unlikely, however, as the observed low consistency of condom use with a regular partner is present in longitudinal analyses of condom use by act of intercourse, in analyses of the behavior of the same woman with different partners, and in longitudinal analyses of partnership status change. The consistency of these findings is a strong indication that the reported association between partner type and condom use is real. Additionally, it is important to note that the intervention encouraged consistent condom use with every partner during every sex act and discouraged women from believing that having only one partner at a time would keep them safe from infection. As such, it is quite possible that the intervention diminished the differences in condom use by partner type that would have been observed had the study not had an intervention component.
Fourth, because only a few women were able to maintain consistent protection by using the female condom exclusively, it was difficult to assess the association between partner type and condom choice during months in which women encountered multiple partners of different types. Similarly, the number of partnerships that changed status during follow-up was small, limiting the ability to study less common or alternating status changes. Power limitations also made it impossible to evaluate specific patterns of barrier use, such as use of the female condom versus use of the male condom, following relationship status changes. These limitations are not severe, however, as even the low-power longitudinal analysis of partnerships achieved statistical significance.
The limitations discussed above are compensated by several important strengths of this study. First, to our knowledge, this is the only report from a large-scale study of women who are not commercial sex workers in which sexual behavior and condom use are evaluated prospectively by partner type. We found that observations commonly made in cross-sectional or retrospective surveys also hold in longitudinal analyses of the experience of individual women and within specific partnerships over time. Participant characteristics did not appear to confound the association between partner type and condom use in the models predicting condom use at each act of intercourse for the entire study group or in those for women with multiple partners during the study. The characteristics of participants were implicitly controlled for in the conditional logistic regression analyses of individual months of follow-up and of partnerships that changed status.
Additionally, all partner-related and condom-use data employed in the present study come from the prospective sexual diaries kept by participants. Prospective diary report of behavior is thought to have two important advantages over retrospective data collection. First, since behaviors are recorded on a daily basis, diary reporting reduces the risk that participants will suffer memory lapses or experience confusion about dates. The analytical problems associated with the inaccurate estimation of behavioral frequencies and the reporting of events that take place outside the reference period are minimized by this [52,53]. Second, prospective diary report of behavior is done privately and, therefore, reduces the likelihood that individuals will give socially desirable answers [54–56]. Face-to-face retrospective reporting of sexual and contraceptive behavior may be particularly vulnerable to self-presentation bias of this sort .
In summary, the results of this study support the hypothesis that condom use varies with the type of sexual partnership and tends to be less consistent as sexual relationships grow more stable and intimate over time. This problem may represent an important challenge to STD and HIV intervention programs aimed at achieving consistent condom use unconditionally with all partners. Offering the female condom as a supplemental form of protection may improve the effectiveness of such programs by facilitating maintenance of consistent barrier use among individuals who are in regular partnerships. It is possible that, to optimize such interventions, research will have to identify the circumstances in which unprotected sex within a regular partnership can be considered as safe.
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