Examinando por Autor "Oberle, Mark W."
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Ítem A case-control study of breast cancer and hormonal contraception in Costa Rica(JNCI, vol. 7, no. 1 (december 1987), 1987) Lee, Nancy C.; Rosero Bixby, Luis; Oberle, Mark W.; Grimaldo, Carmen; Whatley, Anne S.; Rovira, Elizabeth Z.By 1981, 11% of married women in Costa Rica ages 20-49 years had used depot-medroxyprogesterone acetate (DMPA) and 58% had used oral contraceptives (OCs). Since 1977, the Costa Rican Ministry of Health has maintained a nationwide cancer registry. These circumstances provided an opportunity for a population-based, case-control study of DMPA, OCs, and breast cancer in Costa Rica. Cases were 171 women ages 25-58 years with breast cancer diagnosed between 1982 and 1984; controls were 826 women randomly chosen during a nationwide household survey. Cases and controls were interviewed with the use of a standard questionnaire covering their reproductive and contraceptive histories. Logistic regression methods were used to adjust for confounding factors. While few cases or controls had ever used DMPA, DMPA users had an elevated relative risk (RR) estimate of breast cancer of 2.6 (95% confidence limits = 1.4-4.7) compared with never users. However, no do'se-response relationship was found; even the group of women who had used DMPA for less than 1 year had an elevated RR estimate (RR = 2.3; 95% confidence limits = 1.0-5.1). In contrast, OC users had no elevation in RR compared with never users (RR = 1.2; 95% confidence limits= 0.8-1.8). The results of the DMPA analysis are inconclusive. Before decisions are made on whether to continue providing this effective contraceptive method, other ongoing studies will need to confirm of refute these findings.—JNCI 1987; 79:1247-1254.Ítem A population-based serosurveillance of syphilis in Costa Rica(Reprinted from Sexually Transmitted Diseases, Vol. 18, no. 2 (april-June 1991), 1991) Larsen, Sandra A.; Oberle, Mark W.; Sánchez Braverman, Juana M.; Rosero Bixby, Luis; Vetter, Kathleen M.As part of a case-control study to investigate the high incidence of cervical cancer in Costa Rican women, the seroprevalence of the trepnematoses, in particular, syphilis was determined. In each age group, women with a history of two or more sex partners were two to four times more likely to be seroreactive in tests for syphilis than women with zero or one sex partner. The highest percentage of reactive results in the microhemagglutination assay for antibodies to Trepnema pallidum (MHATP) was seen in samples from women aged 50-59 who had had two or more lifetime partners (23.8%). Three observations from our study support reactivity due to syphilis rather than yaws or pinta: ( /) a similar percent of reactive rapid plasma reagin (RPR) card test results among MHA-TP reactors in the two age groups of women who were surveyed (42 vs. 49%) was observed; (2) women who were seroreactive in the MHA-TP had multiple risk factors for STD (low socioeconomic status (9.4%), urban residence (22.8%), first intercourse under 16 years of age (14.1%), and multiple sex partners (26.3%)|, and (j) only sexually experienced women had reactive results in the MHA-TP test.Ítem Confirmación histológica del diagnóstico de cáncer cérvico uterino en Costa Rica 1982-84(Acta Médica Costarricense, Vol. 33; No, 3, 1990) Oberle, Mark W.; Rosero Bixby, Luis; Saeed, MekbelUn panel de patólogos costarricenses efectuó un análisis histológico de las biopsias de 677 casos de cáncer de cuello de útero in situ e invasor diagnosticados en Costa Rica en 1982 - 1984. El panel confirmó el diagnóstico inicial del 81% de los casos de cáncer in situ y del 72% de los casos de cáncer invasor. El panel redigo la severidad del diagnóstico a displasia u otra lesión no cancerosa en el 12% de los casos de cáncer in situ y en el 3% de los casos de cáncer invasor. El 8% de los casos de cáncer invasor fueron reclasificados como in situ. Un 9% adicional podrían ser reclasificados en el mismo sentido, pero hay dudas sobre el diagnóstico definitivo. El error más grave ocurrió en 3% de los casos Inicialmente diagnosticados como de cáncer in situ los cuales fueron reclasificados por el panel como cáncer invasor, pero este error probablemente no afectó el tratamiento de las pacientes. Las modificaciones en el diagnóstico obtenidos en el presente estudio pueden derivarse de un examen más cuidadoso efectuado por el panel o de la dificultad propia del diagnóstico histológico del cáncer de cuello de útero.Ítem 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, LuisContraceptive 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.Ítem Sexual behavior, sexually transmitted diseases, and risk of cervical cancer(Epidemiology, Vol. 6, No. 4, 1995) Stone, Katherine M.; Zaidi, Akbar; Rosero Bixby, Luis; Oberle, Mark W.; Reynolds, Gladys; Larsen, Sandra A.; Nahmias, Andre J.; Lee, Francis K.; Schachter, Juluis; Guinan, Mary E.o explore sexually transmitted diseases and sexual behavior as risk factors for cervical cancer, we analyzed data from a population-based case-control study of breast and cervical cancer in Costa Rica. Data from 415 cases of cervical carcinoma in situ, 149 cases of invasive cervical cancer, and 764 controls were included in the analysis. Multivariate analysis showed that lifetime number of sex partners, first intercourse before age 15 years, number of livebirths, herpes simplex virus type 2 seropositivity, and serologic evidence of previous chlamydial in? fection were predictors of carcinoma in situ. Serologic evidence of previous syphilis was not associated with carcinoma in situ. Predictors for invasive cervical cancer included lifetime num? ber of sex partners, first intercourse before age 15 years, number of livebirths, serologic evidence of previous syphilis, herpes simplex type 2 infection, and chlamydial infection. Cigarette smoking, socioeconomic status, self-reprted history of sexually transmitted diseases, and douching were not associated with either carcinoma in situ or invasive cervical cancer. (Epidemiology 1995;6:409-414)Ítem The effect of using different reference dates for control exposure measurement on relative risk estimates in a case-control study(Journal Clinical Epidemiologycal, Vol. 46, no. 5, 1993) Rampey, Alvin H.; Irwin, Kathleen L.; Oberle, Mark W.; Kinchen, Steven; Lee, Nancy C.; Marsden, Anne; Rosero Bixby, LuisArtículo científico -- Universidad de Costa Rica, Instituto de Investigaciones en Saud. 1993. Debido a las políticas de la revista en la que el artículo fue publicado, no es posible distribuir la edición del editor/PDF. In case-control studies in which case and control enrollment periods are not identical, exposure status for time-dependent variables is often measured relative to a reference date. Using data from a case-control study of the relation between cervical cancer and oral contraceptive (OC) use in which control enrollment began 6 months after the end of case enrollment, we evaluated the effect on odds ratios from using five different reference dates to determine the controls' exposure status. The choice of reference date had little effect on the odds ratios in this study. Reference dates for time-dependent exposure variables should be considered carefully in studies when case and control enrollment periods are not identical.