Luis Rosero Bixby

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Breast cancer and hormonal contraceptives : collaborative reanalysis of individual data on 53 297 women with breast cancer and 100 239 women without breast cancer from 54 epidemiological studies
(The Lancet, Vol. 347, no. 9017, 1996) Collaborative Group on Hormonal Factors in Breast Cancer
The use of female sex hormones as contraceptives began in 1960, since when an estimated 200 million women throughout the world have used them.1 The most widely used type of hormonal contraceptive has been the combined oral contraceptive, which contains an oestrogen and progestagen and is prepared from various compounds in various doses and combinations. Other hormonal contraceptives contain progestagen only, given orally or by injection. Many epidemiological studies have investigated whether hormonal contraceptives might affect breast cancer risk,2 K and the Collaborative Group on Hormonal Factors in Breast Cancer was set up in 1992 to bring together, reanalyse, and publish the worldwide data. The main results are summarised here. Additional results, together with full descriptions of the methods, the studies and the women included, are being published elsewhere.
Breast cancer and hormonal contraceptives : further results
(Contraception, Vol. 54, no. 3: 1S-106S (supplement), 1996) Collaborative Group on Hormonal Factors in Breast Cancer
The Collaborative Group on Hormonal Factors in Breast Cancer has brought together and reanalysed the worldwide epidemiological evidence on breast cancer risk and use of hormonal contraceptives. Original data from 54 studies, representing about 90% o f the information available on the topic, were collected, checked and analysed centrally. The 54 studies were performed in 26 countries and include a total o f 53,297 women with breast cancer and 100,239 women without breast cancer. The studies were varied in their design, setting and timing. Most information came from case-control studies with controls chosen from the general population; most women resided in Europe or North America and most cancers were diagnosed during the 1980s. Overall 41% o f the women with breast cancer and 40% of the women without breast cancer had used oral contraceptives at some time; the median age at first use was 26 years, the median duration o f use was 3 years, the median year o f first use was 1968, the median time since first use was 16 years, and the median time since last use was 9 years. The main findings, summarised elsewhere,1 are that there is a small increase in the risk o f having breast cancer diagnosed in current users o f combined oral contraceptives and in women who had stopped use in the past 10 years but that there is no evidence o f an increase in the risk more than 10 years after stopping use. In addition, the cancers diagnosed in women who had used oral contraceptivestended to be less advanced clinically than the cancers diagnosed in women who had not used them.
Contraceptive use and fertility in Costa Rica, 1986
(International Family Planning Perspectives, Vol. 14, No. 3, (September 1988), 1988) Oberle, Mark W.; Sosa Jara, Doris; Madrigal Pana, Johnny; Becker, Stan; Rosero Bixby, Luis
Contraceptive prevalence in Costa Rica is higher than almost anywhere else in Latin America, with 70 percent of currently married women using a contraceptive method. Differentials in contraceptive use by educational level and between urban and rural areas are actually quite small compared with those in other Latin American countries. While levels of contraceptive use among married women 20-44 years of age remained relatively stable between 1976 and 1986, total fertility rates increased slightly over that period, perhaps because of changing fertility intentions or changing patterns of contraceptive use. For example, Costa Rican women have increased their reliance on barrier methods and decreased use of the pill. The majority of women who were not practicing contraception were either pregnant or breastfeeding an infant; only about one in five nonusers could be considered candidates for contraceptive use. One-fifth of all 15-19-year-old women and two-fifths of all 20-24-year-olds had had premarital intercourse. Most young adults who had had premarital intercourse did not practice contraception at first intercourse.
Estudio prospectivo de las mujeres entrevistadas en dos encuestas de prevalencia anticonceptiva Costa Rica, 1978-1981
(Demografía y Epidemiología en Costa Rica, 1985) Rosero Bixby, Luis
Como parte de un programa internacional de la Westinghouse Health Systems, en Costa Rica se han realizado dos Encuestas de Prevalencia Anticonceptiva. La primera (EPA-78) fue realizada en 1978 por la Dirección General de Estadística y Censos (DGEC), con la colaboración de la Asociación Demográfica Costarricense (ADC). La segunda (EPA-81) fue ejecutada en 1981 por la ADC1. En la muestra de la EPA-81 fueron incluidas algunas áreas de enumeración que también habían sido cubiertas por la primera encuesta. Esto permitió contar con un grupo de mujeres a las que se les ha realizado dos entrevistas, separadas tres anos entre sí. El presente estudio analiza la información de estas re-entrevistas, con el objeto de determinar la veracidad de algunos datos, la estabilidad de algunas opiniones o preferencias declaradas y ciertos cambios ocurridos en ese grupo entre las dos entrevistas. Debido a que es muy raro contar con información de tipo longitudinal para los mismos individuos, como la aquí analizada, este estudio resulta de gran interés. Destaca la oportunidad que ofrece para evaluar la estabilidad y la “saliencia” de las preferencias reproductivas que manifiesta la mujer en una encuesta de este tipo, así como para explorar las posibilidades de predecir la fecundidad en el corto plazo con la información de una sola encuesta.
Fecundidad y uso anticonceptivo en Costa Rica, 1987
(Perspectivas Internacionales en Planificación Familiar, número especial, 1989) Oberle, Mark W.; Sosa Jara, Doris; Madrigal Pana, Johnny; Becker, Stan; Morris, Leo; Rosero-Bixby, Luis
La prevalencia de anticonceptivos en Costa Rica es una de las más altas de América Latina: el 70 por ciento de las mujeres actualmente casadas utilizan algún método anticonceptivo. Los diferenciales en el uso de anticonceptivos en fundón del nivel educativo y entre las zonas rurales y urbanas resultan en efecto muy reducidos en comparación con otros países latinoamericanos. Si bien los niveles de empleo de anticonceptivos entre las casadas de 20 a 44 años se mantuvieron relativamente estables entre 1976 y 1986, durante ese mismo lapso, las tasas globales de fecundidad aumentaron ligeramente, quizá debido a un cambio en las intenciones reproductivas o en las modalidades del uso de anticonceptivos. Las costarricenses, por ejemplo, han pasado a confiar más en métodos de barrera y no recurren ya tanto a la píldora. La mayoría de las que no practicaban la anticoncepción estaban o embarazadas o amamantando: sólo aproximadamente una de cada cinco no usuarias podía considerarse candidata a utilizar anticonceptivos. La quinta parte de las mujeres de 15 a 19 años y dos quintos de las de entre 20 y 24 habían tenido relaciones sexuales premaritales. La mayor parte de las jóvenes de este grupo no había empleado método anticonceptivo alguno la primera vez.
Interaction, Diffusion, and Fertility Transition in Costa Rica: Quantitative and Qualitative Evidence
(Dynamics of Values in Fertility Change. Oxford University Press, 1999) Rosero Bixby, Luis
This chapter examines the role played by diffusion through social interaction in the Costa Rican fertility transition. The literature about the causes of fertility transition has traditionally focused on the socio-economic and cultural determinants of the motivation for having large or small families. To a somewhat lesser degree, it has also considered supply factors limiting or facilitating access to contraception, that is, the role of family planning programmes. The concern here is with the third type of causal agent of fertility transition, that is, the autonomous spread, or contagiousness, of fertility control. If Costa Rican data support the proposition that social contagion processes shaped fertility decline, then an empirical foundation exists for Simmons's claim that 'programmes may generate their own demand through diffusion from early users to others'.
Oral contraceptives and cervical cancer risk in Costa Rica
(Journal of the American Medical Association, Vol. 259, no. 1, 1988) Irwin, Kathleen L.; Rosero-Bixby, Luis; Oberle, Mark W.; Lee, Nancy C.
To examine the relationship between cervical cancer and oral contraceptive (OC) use, we analyzed data from a population-based, case-control study in Costa Rica. Women aged 25 to 58 years in whom cervical cancer was diagnosed and reported to the National Tumor Registry were examined as two separate case groups: invasive cervical cancer and carcinoma in situ (CIS). Controls were women aged 25 to 58 years identified through a national survey. Women who had used OCs had no increased risk of invasive cervical cancer compared with women who had never-used OCs (relative risk, 0.8; 95% confidence interval, 0.5 to 1.3). Women who had used OCs had an increased risk of CIS compared with those who had never used OCs (relative risk, 1.6; 95% confidence interval, 1.2 to 2.2). However, further analyses indicated that this increased risk was confined to those who had recently used OCs. Also, the risk of CIS was not elevated in subgroups in which a history of cervical smears was not strongly linked to OC use. The elevated risk of CIS among OC users may therefore reflect a bias caused by enhanced detection of disease rather than a causal association.

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Examinando Luis Rosero Bixby por Materia "ANTICONCEPTIVOS"

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