Extrarelational sex among Mexican men and their partners' risk of HIV and other sexually transmitted diseases.

OBJECTIVES: This study explored the risk of HIV and other sexually transmitted diseases (STDs) among married and cohabiting women in Mexico City, Mexico, derived from their partners' sexual behaviors. METHODS: Results were derived from the first population-based household survey in Mexico that investigated male sexual behavior. Analyses were restricted to sexually active married or cohabiting men (n = 3990). RESULTS: Fifteen percent of the men reported extrarelational sex during the past year, 9% reported condom use during last intercourse, and 80% perceived no HIV risk. Most secondary partners were coworkers, mistresses, or friends. CONCLUSIONS: Targeted HIV and STD prevention efforts appear necessary because a substantial number of women may be at risk.

Assessment of non-response bias in a probability household survey of male same-gender sexual behavior.

OBJECTIVE: To assess non-participation bias in a survey of male sexual behavior. MATERIAL AND METHODS: A household survey was carried out in 1992-1993 using a probability sampling frame in Mexico City. Demographic variables were available for all eligible men. The extent of non-participation bias was estimated using a version of the Heckman method, which utilizes two equations, one to predict participation and the other to predict reports of same-gender sexual behavior. RESULTS: A total of 8,068 of the 13,713 eligible men completed a face-to-face questionnaire (response rate 59%); 173 men (2.1%) reported bisexual behavior in their lifetime, and 37 (0.4%) reported only male partners. Survey participation was predicted using demographic variables: 67% of the observations were correctly predicted by a probit regression model: 82% of participants and 53% of non-participants (pseudo-r2 = 0.13). Same-gender sexual behavior was predicted by variables indicating attachment to gay/bisexual social networks, history of sexually transmitted diseases, positive attitudes towards gay and bisexual males, and lack of support from male relatives. Ninety-seven per cent of the cases was correctly predicted by the probit model (pseudo-r2 = 0.14). The correlation between these two equations was not statistically significant. CONCLUSIONS: These results indicate that prevalence estimates of same-gender sexual behavior among Mexico City men were not biased by selective survey participation. Careful selection and training of household interviewers may have assisted in minimizing potential bias.

[Condom use by men with non-stable partners in Mexico City]. / Uso del condón en hombres con parejas no estables en la Ciudad de México.

OBJECTIVE: To analyze the association between sociodemographic variables and condom use during vaginal sexual relationships with non-stable partners. MATERIAL AND METHODS: Data were taken from a household probability survey on sexual behavior in 1992-1993 in the Mexico City Metropolitan Area. Of the completed survey were obtained 8,068 men of 15 to 60 years of age. 1,535 were selected because they reported that their last sexual relationship with vaginal intercourse had been with a non-stable partner. Principal component analyses were conducted to groups of variables with common underlying structures, these components and other variables were included in a logistic regressions. Condom use during last intercourse was the dependent variable. RESULTS: Feeling that sex with condoms or sex without penetration could be pleasurable, a high ranking in a scale on self-efficacy for condom use, compulsion for using a condom because of being afraid of contracting HIV/AIDS were positively associated with using a condom in the last sexual intercourse. Marital status, schooling, and the number of episodes of sexually transmitted diseases were significantly associated with condom use. Perception of inevitability of becoming infected due to lack of trust in condoms was negatively associated with its use. None of the variables regarding knowledge on HIV/AIDS, including means of transmission and ways to prevent its infection, showed any significant association with condom use. CONCLUSIONS: Even when information is considered important in educational strategies, it might be more important to promote a positive perception on condoms and safe sex as pleasurable (at the individual and social level), as well as the promotion of self-efficacy on being able to use a condom or enforce preventive behaviors against HIV infection.

[Maximal aerobic capacity and sports activity in Mexicans from 13 to 56]. / Capacidad aerobia máxima y actividad deportiva en mexicanos de 13 a 56 años de edad.

The maximum oxygen uptake (VO2máx) of Mexicans living at 2240 m altitude was measured to obtain reference values relating VO2máx with athletic performance, and to evaluate the impact of this measure of cardiorespiratory fitness and sport activity on the ageing process. Clinically healthy male individuals (N = 138), 13 to 56 years of age, were divided into groups by decade and according to sport participation. The VO2máx maximum values for power (Power max), and heart rate (HRmax) were measured while subjects exercised on an electronic cycle ergometer using an open circuit spirometry system. The maximum power index (PImax) was also calculated. The VO2máx indicated that modes of sport activity positively affected aerobic power and "counteracted" age-related decreased in HRmax-, VO2máx-, Powermax-, and PImax.

[The homosexual transmission of HIV/AIDS in Mexico]. / Transmisión homosexual del VIH/SIDA en México.

OBJECTIVE: To analyze HIV homosexual transmission in Mexico, epidemic trends and biological and social risk factors. METHODS: This analysis is based on 19,090 notifications of AIDS cases and on a review of two previous studies that include 3,029 behavioral interviews (together with HIV serological screening tests) carried out at the Information Center of the Mexican Council for Control and Prevention of AIDS (CONASIDA) (1988-89) and during a 1988 study in six Mexican cities. Cities were included because they were the larger in the country and/or because they were the larger in the country and/or because they were touristic places (Mexico City, Guadalajara, Monterrey, Acapulco, Tijuana and Merida). Logistic regressions were used to estimate the odds ratios for HIV seropositivity and for condom use. RESULTS: Seventy-two percent of the total reported AIDS cases (19,090) up to June 30, 1994, were associated with male homosexual behaviors. In absolute numbers, cases under this category exhibited a rising trend until the end of 1993. HIV seroprevalence was 31% in 2,314 men with homosexual practices who attended "FLORA", the AIDS Information Center in Mexico, from January 1988 to June 30, 1989. The main predictive variables for seropositivity were exclusive homosexual behavior, more than 40 lifetime sexual partners, mixed sexual behavior (both insertive and receptive and intercourse), sex with a person with AIDS, history of syphilis, and anal or genital warts. In general, these risk factors (data from the Information Center) are similar to those found in the six Mexican cities study. There were significant differences in HIV prevalence among the high-risk city samples (the highest in Mexico City with 25% and the lowest in Monterrey with 2.4%). Reported condom use was very low in both studies: only 5% used a condom in all of their sexual relationships. A statistically significant protective effect for HIV infection was found only for those who reported using a condom in all sexual encounters. In the six cities study, city of residence was a strong predictor of condom use. CONCLUSIONS: HIV homosexual transmission is steadily increasing; the recent decline in the percentage of homosexual cases is artificial because of the increment of cases under other categories. Men who report exclusive homosexual behavior have higher prevalence rates of infection than bisexual men. Individuals with insertive/receptive behavior (mixed) have the highest risk for HIV seropositivity, mainly because of sociological, rather than biological reasons. This difference in risks for HIV and condom use may be related to the selection of sexual partners from specific social networks. Condom use was demonstrated to be an effective method for preventing HIV seropositivity among those who always use condoms. However, it is alarming that only 5% of respondents reported condom use in all sexual encounters. Social and geographic differences in the cumulative numbers of cases, HIV prevalence, sexual practices and condom use must be taken into account in the planning of preventive programs.

[AIDS mortality in Mexico from 1983 to 1992. The trends and years of potential life lost]. / La mortalidad por el SIDA en México de 1983 a 1992. Tendencias y años perdidos de vida potencial.

OBJECTIVE: To describe trends in AIDS mortality in Mexico from 1983 to 1992, as well as years of potential life lost (YPLL) and years of potential productive life lost (YPPLL) due to AIDS. MATERIAL AND METHODS: A retrospective review of databases available in Mexico that code mortality from AIDS was performed. Since AIDS was not coded specifically as a cause of death until 1988, for the period 1983-1987 the database of AIDS cases from the national AIDS registry provided by the Instituto Nacional de Diagnóstico y Referencia Epidemiológicos of the Ministry of Health was used. For the 1988-1992 period, a review of the mortality registry was provided by the Dirección General de Estadística, Informática y Evaluación of the Ministry of Health. To calculate YPLL and YPPLL we used the upper limit of expected life in Mexico for 1990 (70.79 years for men and 75.71 for women). RESULTS: Through 1992, there have been 8,204 deaths attributable to AIDS in Mexico (86% were men) with a rate of 2.9 deaths/100,000. In 1992 AIDS was the 19th leading cause of death in the country. The most affected age groups are the 25-34 and 35-44 years-old (especially amongst men) in which AIDS has now displaced pulmonary tuberculosis, suicide and self-inflicted injuries, diabetes mellitus, cerebro-vascular disease and alcohol dependency syndrome as leading causes of death in men. Our data suggests that AIDS has caused, from 1983 through 1992, 247,045 YPLL in men and 48,703 in women as well as 206,211 YPPLL in men and 29,793 in women. CONCLUSIONS: AIDS is at present one of the leading causes of death in Mexico. However, due to under-reporting, these estimates should be considered conservative and as lower-bound estimates. This data suggests that professionals are over-represented among AIDS cases, in comparison with the 1990 Population Census. This does not happen to be the case among women who are housewives.

[The serological exam for the human immunodeficiency virus (HIV) as part of the premarital exams]. / El examen serológico para el virus de la inmunodeficiencia humana (VIH) como parte de los exámenes prenupciales.

Due to the presence of the acquired immune deficiency syndrome (AIDS), it has been frequently stated, by several segments of the society, that mandatory human immunodeficiency virus (HIV) testing as premarital requirement is useful for AIDS prevention. The usefulness of these tests among general population are discussed, as well as some problems for its eventual implementation, concluding that this screening procedure is impractical, inefficient and expensive as a public health measure. The overall HIV prevalence in Mexico is very low (4 per 10,000), therefore, a person from this population with a positive screening test, has a slight chance of being truly infected (16%), in other words, screening tests have a low positive predictive value in general population. Conversely, having a negative screening test, predicts this state accurately (negative predictive value greater than 99%). Several problems arise when HIV screening tests are applied: logistics, for example avoidance of the tests, economic, ethic, and human rights problems, among others. It is concluded that mandatory HIV screening tests are not cost-efficient and that there are other options, for instance education, which would imply better changes for HIV prevention.

HIV-1 seropositivity and behavioral and sociological risks among homosexual and bisexual men in six Mexican cities.

We report on the epidemiology of sexual behaviors, HIV-1 seroprevalence, and condom use in gay and bisexual men in six Mexican cities in 1988 and test the extent to which variations in sexual behavior and sociological risks are responsible for variations in prevalence. Seroprevalence rates among samples in six cities ranged from 2% to 25%. In multiple logistic regression models controlling for city, insertive/receptive behavior (IRB), and meeting partners in bathhouses, the following were independently related to seropositivity (p less than 0.05): city, IRB, syphilis, sex with a person with AIDS, and meeting partners in bathouses. The independent risks associated with categories of IRB were no or almost no activity (odds ratio 1.0), only insertive (3.0), mostly insertive (4.9), mixed (6.0), mostly receptive (3.3), and only receptive (0.9). The condom use rate on last sexual encounter was 30%. The main sexual risk for HIV-1 infection is not exclusively receptive anal sex, but rather mixed behavior. This association may be explained by the infectious state of the partner pools. The sociologic risk variables (national and local partner pools) are better predictors of seroprevalence than behavioral variables, such as the number of partners or use of condoms. These results imply that more effective individual strategies for risk reduction are needed, including better knowledge concerning the risk status of partners.

[Years of potential life lost: their usefulness in the analysis of mortality in Mexico]. / Años de vida potencial perdidos: su utilidad en el análisis de la mortalidad en México.

The evolution of the epidemiology of mortality in developing countries requires the use of indicators additional to cause specific mortality rates. This paper presents the leading causes of potential years of life lost in Mexico in 1983, by sex. Methodologic discussion focused on age limits and relative numbers. The indicator proved useful to assess the impact of infectious diseases, accidents and homicides as causes of premature death. It was also useful to identify years of potential life lost attributable to specific age and sex groups. The use of years of potential life lost provides valuable information to epidemiologic mortality analysis.