[Risk factors for the heterosexual transmission of HIV from man to woman: a Spanish multicenter study]

Abstract

Background: The aims of this study were to estimate the rate of heterosexual transmission of HIV in a population of intravenous drug users (IVDU), as to well as to identify the possible risk factors associated.

Methods: One hundred thirty heterosexual couples were analyzed in which the male was seropositive for the human immunodeficiency virus (HIV) with the only possible risk factor for the companion being the sexual intercourse with the case index.

Results: The rate of global transmission estimated was 16% (confidence interval of 95% = 10-22.4%). The risk factors significantly associated to HIV transmission were: case index of over 30 years of age (OR = 3.1), clinical status IV (OR = 4.1), less than 0.8 x 10(8) lymphocytes/I (OR = 7), antecedents of sexually transmitted disease (STD) in the woman (OR = 4), and the practice of anal intercourse (OR = 3.1). In the multivariate analysis only the clinical status of the case index and the STC antecedents of the woman were statistically significant (p less than 0.05).

Conclusions: In this study some of the classical risk factors for the heterosexual transmission of HIV have been confirmed, and the importance of decreasing the prevalence of STD in the IVDU collective in Spain has been corroborated to lower heterosexual transmission and, indirectly the vertical transmission of AIDS.

PIP: The objectives of this study, which formed part of the Multicenter European Study of Heterosexual Transmission, were to estimate the rate of heterosexual HIV transmission in a population of intravenous drug users, to describe the sexual and contraceptive habits of the couples, and to identify possible risk factors for heterosexual HIV transmission. 130 couples from 17 centers in Andalusia, Cataluna, and Madrid, who met the criteria and agreed to participate, were studied between June 1988 and February 1990. The index case in all couples was a male partner seropositive for HIV infection. Exclusion criteria for the female partner included intravenous drug use, blood transfusion since 1980, or sexual relations in the past 6 months with an individual other than the index case. All women were screened for HIV antibodies with the ELISA test, with confirmation of positive results by Western blot or indirect immunofluorescence. Around 70% of participants in center collecting sociodemographic information were illiterate of had primary educations, and over half had children. 40% of the index cases had a history of sexual contacts with prostitutes, over 20% reported more than 5 sexual partners in the past 5 years, and 18% had had other sexual partners in addition to the partner interviewed since learning of their seropositivity. Over half of couples had been together for more than 5 years. 32% of the women reported other sexual partners in the past 5 years, excluding the past 6 months. 70% of the couples interviewed reported having sexual relations 1-3 times weekly. 25% reported having anal intercourse. 33% of the men and 17% of the women reported a history of sexually transmitted diseases. 11 additional cases of sexually transmitted disease in men and 8 in women were diagnosed in the study. The rate of transmission was 16% (21/130), with a 95% confidence interval between 10-22.4%. The risk factors significantly associated with HIV transmission were: index case over 30 years old (odds ratio of 3.1), clinical stage 4 (odds ratio 4.1), lymphocyte level under 800 (odds ratio of 7), history of sexually transmitted diseases in the woman (odds ratio of 4), and practice of anal intercourse (odds ratio of 3.1). The clinical stage of the index case and history of sexually transmitted disease in the woman were the only risk factors statistically significant in multivariate analysis. The lymphocyte population was omitted from the multivariate analysis, since it was known for only 63 men. The possible effect of condom use could not be determined because only 4 couples used them regularly.