***TASK*** the task is to summarize an input biomedical literature in six sentences 
    ***INPUT*** the input is a biomedical literature 
    ***OUTPUT*** the output is the summary of an input biomedical literature in six sentences 
    ***DOCUMENTATION*** 
    ***EXAMPLES*** 
    Input: This study identified a sample of young African-American men and women classified as having multiple sex partners or one sex partner . Of the 149 men , 71 ( 47 % ) were classified as having multiple sex partners and 78 ( 53 % ) as having one sex partner . Of the 165 women , 29 ( 19 % ) were classified as having multiple sex partners and 126 ( 81 % ) as having one sex partner . Results indicated that the groups did not differ in their knowledge about acquired immunodeficiency syndrome ( AIDS ) . However , attitudes about condom use differed significantly by gender ( P less than .01 ) and by multiple sex status ( P less than .001 ) . Angry reactions regarding the negotiation of condom use occurred more with men than with women ( P less than .05 ) . Men and members of the multiple sex partners group tended to engage in more risky sexual behavior . These two groups also had a significantly ( P less than .001 ) higher incidence of gonorrhea . While the multiple sex partners group had significantly more smokers ( P less than .01 ) , drinkers ( P less than .01 ) , and crack users ( P less than .05 ) , men were significantly higher consumers of marijuana ( P less than .001 ) and alcohol ( P less than .01 ) . Overall , the results indicate that African Americans are knowledgeable about AIDS , but there appears to be a gap between knowledge and risky sexual behaviors . Prospect i ve studies are needed to clarify the factors that determine the relationship ( or lack of ) between knowledge and risky sexual behaviors . Without such studies , a major part of the foundation that is needed for the development of sensitive and effective AIDS prevention programs for African Americans will be missing Many theoretical models examining health risk behaviors , such as sexual risk taking , assume intentions directly predict behavior , and intentions are sometimes measured as a proxy for behavior . Given that there is often a discrepancy between intentions and behaviors ( e.g. , Sheeran , 2002 ) , this study addressed factors that predict intention – behavior congruence . Specifically , utilizing a prospect i ve design , the goal of the study was to determine if characteristics of university students ' last sexual encounter predicted whether those students who intended to use condoms , contraception , or dual methods  did so in their last sexual encounter with both relationship and casual partners . The seven tested variables were  condom planning and preparatory behaviors , mood , sexual arousal , substance use , perceived partner attractiveness , intention certainty , and intention stability .  Data were collected from 520 American undergraduate students at a medium-sized university . The six discriminant function analyses examining the intention – behavior relationship were able to correctly classify between 74 % and 92 % of the participants concerning whether intenders engaged in safe sex behaviors . The variables that best discriminated between behavior engagement over the six analyses were intention stability , intention certainty , and engagement in condom preparatory behaviors . The implication s of these results for sexual risk prevention and intervention research are discussed We create and analyze a mathematical model to underst and the impact of condom-use and sexual behavior on the prevalence and spread of Sexually Transmitted Infections ( STIs )  . STIs remain significant public health challenges globally with a high burden of some Sexually Transmitted Diseases ( STDs ) in both developed and undeveloped countries . Although condom-use is known to reduce the transmission of STIs , there are a few quantitative population -based studies on the protective role of condom-use in reducing the incidence of STIs . The number of concurrent partners is correlated with their risk of being infectious by an STI such as chlamydia , gonorrhea , or syphilis . We develop a Susceptible-Infectious-Susceptible ( SIS ) model that stratifies the population based on the number of concurrent partners . The model captures the multi-level heterogeneous mixing through a combination of biased ( preferential ) and r and om ( proportional ) mixing processes between individuals with distinct risk levels , and accounts for differences in condom-use in the low- and high-risk population s. We use sensitivity analysis to assess the relative impact of high-risk people using  condom  as a prophylactic intervention to reduce their chance of being infectious , or infecting others . The model predicts the STI prevalence as a function of the number of partners of an individual , and quantifies how this distribution of effective partners changes as a function of condom-use . Our results show that when the mixing is r and om , then increasing the  condom-use  in the high-risk population is more effective in reducing the prevalence than when many of the partners of high-risk people have high risk . The model quantifies how the risk of being infected increases for people who have more partners , and the need for high-risk people to consistently use condoms to reduce their risk of infection The objective of this paper is to get detailed information on the dynamics of condom use with various partner types , including consistency of use , and to estimate the frequency of unprotected intercourse . The study is based on a prospect i ve cohort study of 222 urban workers in urban Zimbabwe . Respondents ' sexual behaviour and condom use  were tracked for a period of six weeks using daily interviewer-administered question naires . In total , the observation period covers 9,324 person-days , during which 4,601 sexual contacts were reported . The results indicate that most sexual encounters with casual partners are protected , and condom use with these partners is very consistent . However , although the majority of sex acts with regular non-marital partners are protected , only four out of ten men with regular partners used condoms consistently . Because many men have both regular and casual partners , fewer than one in seven males used condoms in all their sex acts . We estimate that nearly half of all males have more than 85 unprotected sex acts per year . Although many of these acts are with spouses , who have comparatively low risk , we estimate that about one in five men have 25 or more unprotected acts with regular non-marital partners annually . We conclude that regular partners are likely to be a major source of HIV transmission in Zimbabwe , partly because condom use is inconsistent and partly because they account for a large share of all sex acts . Given that over one in four adults in the general population are HIV-positive , and that some studies show that married persons have the highest HIV prevalence , it is important for future HIV programmes to focus on increasing levels of protection with regular partners OBJECTIVE : To examine the effect of patient defined non-regular sexual relationships and other risk behaviours on the incidence of sexually transmitted infections in heterosexual men and the role of condom use in the prevention of their spread . DESIGN : A prospect i ve cross sectional study of sexual behaviour reported by a st and ardised self administered question naire in new patients who presented for screening and diagnosis . SETTING : A genitourinary medicine clinic in west London . SUBJECTS : 957 consecutive newly attending heterosexual men who completed a sexual behaviour question naire in 1993/94 . MAIN OUTCOME MEASURES : Variables relating to sociodemographic status , sexual behaviour , condom use , sexually transmitted infections and testing for HIV infection , stratified by the reporting of non-regular partners . RESULTS : We found that the 65 % of men who reported non-regular sexual partners were more likely to be white collar class ( d = 7.5 % , 95 % CI = 1.3 , 13.7 ) and to have had sexual intercourse with non-United Kingdom born women ( d = 7.8 % , 95 % CI = 3.5 , 12.2 ) . They also reported coitarche before 16 years of age ( d = 13.4 % , 95 % CI = 8.0 , 18.8 ) and many more sexual partners both in the last year ( d = 13.1 % , 95 % CI = 10.2 , 16.0 ) and in their lifetime ( d = 27.9 % , 95 % CI = 21.6 , 34.2 ) . They were significantly more likely to practise anal intercourse ( d = 8.7 % , 95 % CI = 3.3 , 14.1 ) , to smoke ( d = 16.3 % , 95 % CI = 9.8 , 22.6 ) , to drink alcohol ( d = 4.9 % , 95 % CI = 1.2 , 8.6 ) , and to have chlamydial infection ( d = 5.7 % , 95 % CI = 2.2 , 9.2 ) , of which 30 % was sub clinical . Increasing condom use with regular partners correlated with decreasing incidence of urethral infection ( gonorrhoeal and /or chlamydial infection ) ( p < 0.03 ) and c and idal balanitis ( p < 0.03 ) and a greater likelihood of no infection being detected ( p = 0.0002 ) . Use of condoms with non-regular partners was much more frequent than with regular partners ( d = 21.4 % , 95 % CI = 16.7 , 26.1 ) . However , we found evidence of oral transmission of urethral gonorrhoea and chlamydial infection among men who reported always using condoms . HIV infection was found in only two men ( 0.2 % ) , both of whom reported intercourse with non-United Kingdom born women . CONCLUSIONS : Heterosexual men who reported non-regular sexual relationships compensated for their increased risk lifestyle by using condoms more frequently and showed only an increased incidence of chlamydial infection . More consistent condom use with regular partners was significantly associated with the absence of sexually transmitted infection . These findings suggest that transmission between regular partners has been underestimated Objectives : To examine the association between type of sexual partnership and condom use consistency . Design : A prospect i ve follow-up study of women attending two urban clinics for sexually transmitted diseases ( STD ) . Methods : Sexual diaries recording barrier method , partner initials and partner type for each act of intercourse were kept by 869 women .  Condom use by partner type was evaluated in three ways in the entire group : among women who encountered multiple partners , during months in which women encountered multiple partners , and within sexual partnerships that changed status during the study . Results : Consistency of condom use was higher with new and casual partners than with regular partners in the entire group and among women who encountered multiple partners . In months in which partners of different types were encountered , condom-use consistency was higher with new and casual partners than with regular partners . Consistent condom use decreased in partnerships that changed status from new to regular . The  female condom  was used more often with regular partners than with new or casual partners in the entire study group , among women who encountered multiple partners , and during months in which a woman achieved consistent use with her regular partner . Conclusions : This study provides strong evidence that condom use behavior is modified by partner type . Observations about condom use and partner type made in cross-sectional or retrospective surveys also hold in the present longitudinal analyses of individual women and of partnerships that change status . The female condom may be an important option for achieving consistent protection within stable partnerships CONTEXT Women who rely on long-term hormonal contraception  may neglect to use condoms , and thus increase their risk of contracting sexually transmitted diseases , including AIDS . METHODS Data from a prospect i ve , multisite study were collected to examine the probability of condom use among 1,073 new users of either the contraceptive implant or injectable ;  users were interviewed when they accepted their method and again six months to one year later . Multivariate logistic regression analyses identified factors that significantly predicted the likelihood of dual method use . RESULTS Condom use dropped markedly among women who adopted long-term hormonal contraception . The proportion who always used condoms in the previous three months fell from 21 % at the time of adoption to 11 % at follow-up . Among women with one sexual partner , this decrease was from 20 % to 10 % ; however , among those with more than one partner , use increased from 25 % to 31 % . The factors significantly predicting dual method use included previous condom use ( odds ratio of 2.5 ) , receipt of AIDS-specific counseling ( odds ratio of 1.6 ) , the perception of being at some risk of AIDS at baseline ( odds ratio of 1.4 ) and having had more than one sexual partner over the study period ( odds ratio of 5.4 ) . In addition , injectable users , teenagers and black women were more likely than other women to use condoms with their hormonal method . CONCLUSIONS Although condom use among all women declined markedly once they initiated long-term hormonal contraception , frequency of condom use varied by subgroup and was associated with several factors . Most importantly , women with more than one sexual partner and those who received a message during counseling on the need to continue using condoms were more likely than others to use condoms in conjunction with the implant or injectable Abstract Characteristics of sexual partnerships , as well as those of the individuals involved , might influence the use of condoms and risk of HIV transmission . We set out to identify characteristics of non-spousal sexual partnerships associated with condom use at last sex in the previous year and HIV infection in the previous three years among sexually active young people in rural South Africa . We conducted an analysis of follow-up data ( collected in 2004 ) from a cohort of 14–35-year old men and women recruited to a cluster-r and omised trial . Data on 1647 non-spousal sexual partnerships during the previous year were reported in 2004 and analysed alongside new HIV infections over the previous three years among 762 individuals who were HIV-negative in 2001 .  Structured interviews elicited information on sexual behaviour . HIV serostatus was assessed through oral-fluid  ELISA . Condom use at last sex was reported for 615/1647 non-spousal sexual partnerships ( 37.3 % ) and was more commonly reported by individuals who were younger , more educated and aware of their HIV status . Condom use was more common in casual partnerships , those where the male partner was younger , where sex was less frequent and where the respondent believed the partner to have other sexual contacts . New HIV infection in the last three years was identified for 87/762 individuals ( 11.4 % 
    Output:
    
Results Based on systematic review , we show that a greater number of people used condoms  during sexual contact with casual partners than with steady partners .
Furthermore , people with multiple partners use condoms more frequently than people with a single partner alone .
Our mathematical model revealed a positive relationship between the effective reproduction number and the proportion of people with multiple partners .
Nevertheless , the association was reversed to be negative by employing a slightly greater value of the relative risk of condom use for people with multiple partners than that empirically estimated .
Conclusions Depending on the correlation between condom use and the existence of concurrency , association between the proportion of people with multiple partners and the reproduction number can be reversed , suggesting the sexually active population is not necessary a primary target population to encourage condom use ( i.e. , sexually less active individuals could equivalently be a target in some cases )