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 A population-based serosurveillance of syphilis in Costa Rica(Sexually Transmitted Diseases, vol. 18, no. 2, 1991) Larsen, Sandra; 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 treponematoses, 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 Treponema 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 Cervical cancer risk and use of depot-medroxyprogesterone acetate in Costa Rica(International Journal of Epidemiology., Volumen 17, no. 4, 1988) Oberle, Mark W.; Irwin, Kathleen L.; Rosero-Bixby, Luis; Fortney, Judith A.; Lee, Nancy C.; Whatley, Annes S.; Bonhomme, Michele G.The long-term safety of the injectable contraceptive, depot medroxyprogesterone acetate (DMPA), has been the subject of intense debate, chiefly because of reports of breast and endometrial neoplasia in animal studies. Most epidemiological studies of DMPA use and cancer have been hindered by small sample size and short periods of potential latency.1-3 A recent, large case-control study by the World Health Organization (WHO) did not identify any overall increased risk of invasive cervical cancer among DMPA users.4-5 However, women who had used DMPA for five years or more had an elevated risk of invasive cervical cancer, compared to never users (odds ratio = 2.2, 95% confidence interval, 1.2 - 4.2). This increased risk was confined to long-term users who were under 46 years of age at diagnosis or who began using DMPA before 30 years of age. The WHO study did not include cases of carcinoma in situ (CIS). Costa Rica offers an opportunity to examine the relationship between DMPA use and cervical cancer, bfccause of its high incidence of cervical cancer and the popularity of DMPA after its introduction in the early 1970s. In 1983, cervical cancer was the most commonly reported cancer and the second leading cause of cancer mortality among Costa Rican women.6 The reported incidence of invasive cervical cancer in 1983 was 36.2/100 000 women, one of the highest rates in the world.6 DMPA has been a popular contraceptive in Costa Rica; approximately 11 % of currently married women, 15-49 years of age have used an injectable contraceptive, chiefly DMPA.7 However, since 1983, DMPA has not been approved for contraceptive use in Costa Rica. To further address the long-term safety of DMPA, the Costa Rican Demographic Association conducted a population-based, case-control study of cervical and breast cancer in Costa Rica in 1984-85. We report here our analysis of the association between DMPA use and cervical cancer. The breast cancer cases are the subject of a separate report.8Ítem 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 Estudios de detección selectiva del cáncer de cérvix y del cáncer de mama en Costa Rica(Bol Of Sanit Panam, Vol. 109, no. 3, 1990) Irwin, Kathleen L.; Oberle, Mark W.; Rosero-Bixby, LuisEl cáncer de cuello uterino (cáncer de cérvix) y el cáncer de mama son las principales causas de morbilidad y mortalidad femenina por cáncer en Costa Rica. Se evaluaron los métodos de detección de estos dos tipos de cáncer en las mujeres costarricenses de 25 a 58 años a partir de los datos de una encuesta nacional realizada en 1984 y 1985. El frotis de cuello uterino (frotis cervical) es un método muy utilizado para detectar el cáncer de cérvix, y 83,5% de las mujeres señalaron que se habían hecho por lo menos un frotis. Sin embargo, más de un tercio no se habían hecho el primer frotis o la primera exploración ginecológica hasta los 30 años, mucho después de la edad media de la primera relación sexual. Las pruebas de detección fueron menos comunes en grupos de mujeres de alto riesgo de cáncer de cérvix, incluidas las que tenían múltiples compañeros sexuales y las que habían tenido varios hijos. Un análisis de casos y testigos reveló que él riesgo de cáncer invasor en las mujeres que se habían hecho un frotis cervical era alrededor de la mitad del riesgo correspondiente en las mujeres que no se habían hecho ningún frotis. Menos de la mitad de las mujeres señalaron que se habían hecho explorar las mamas por un profesional o que habían practicado la autoexploración mamaria. Las mujeres mayores de 50 años, que por su edad se encuentran en el grupo más expuesto al cáncer de mama, eran las que con menor frecuencia se habían sometido a ambos tipos de exploración. Se podría aumentar la frecuencia de las pruebas de detección de los cánceres de cérvix y de mama prestando especial atención, por medio del sistema de servicios de salud existente, a las mujeres de los grupos de alto riesgo que no se hayan sometido a suficientes exploraciones.Ítem 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, LuisLa 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.Ítem Fertility change in Costa Rica 1960-84 : analysis of retrospective lifetime reproductive histories(Journal of biosocial science, no. 20, 1989) Rosero-Bixby, Luis; Oberle, Mark W.Lifetime reproductive histories of a 1984—85 nationally representative sample of 870 women aged 25-59 years provided data to describe the evolution of fertility, contraception, breast-feeding, and natural fecundability in Costa Rica between 1960 and 1984. The contraceptive prevalence rate increased from 23% in 1965 to 58% in 1975 and 66% in 1984. Duration of breast-feeding was stable during the 1960s, decreased in the early 1970s, and increased after about 1976. Fecundability among women who did not practice contraception was lower than expected and declined between 1960 and 1975, probably because of selection effects. Despite a high consistency between estimations from the reproductive histories and other sources of data, some suggestion of omissions of short periods of contraceptive use in the distant past was detected. The survey may have reduced recall errors by using a calendar that summarizes major life events together. The analysis demonstrated the feasibility and usefulness of asking for lifetime reproductive histories in fertility surveys in developing countries.Ítem Herpes simplex virux type 2 antibodies : high prevalence in monogamous women in Costa Rica(The American Journal of Tropical Medicine and Hygiene, volumen 41, no. 2, 1989) Oberle, Mark W.; Rosero-Bixby, Luis; Lee, Francis K.; Sánchez Braverman, María; Nahmias, Andre J.; Guinan, Mary E.We studied the prevalence o f antibody to Herpes simplex virus types 1 and 2 (HSV-J and HSV-2) in 766 randomly selected Costa Rican women 25-59 years of age in a national household survey in 1984-1985. Overall, 97.1% were seropositive for HSV-1 and 39.4% for HSV-2. Only 1.1% o f HSV-2 seropositive women gave a history o f symptomatic genital herpes. HSV-2 virus antibody increased with age and with the number of lifetime sexual partners. HSV-2 seroprevalence among women who reported only 1 lifetime sexual partner was almost twice as high as the prevalence among women who denied sexual experience (30.5% vs. 17.7%) and reached 79.2% among women with > 4 partners. HSV-2 seroprevalence was lower among women whose partners used condoms: 28.9% for those who had used condoms for at least 2 years vs. 44.3% for those who never used condoms.Ítem 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.Ítem Prevalencia de enfermedades de transmisión sexual en las mujeres de Costa Rica(Revista Costarricense de Ciencias Médicas, volumen 11, no. 2, 1990) Oberle, Mark W.; Rosero-Bixby, Luis; Larsen, SandraPocos estudios han descrito la epidemiología de las infecciones por enfermedades de transmisión sexual (ETS) basándose en muestras serológicas representativas de la población en general y no solo en grupos selectos de pacientes. Ello se debe a la dificultad para obtener serologías en muestras representativas de la población y a la falta de información sobre el historial médico y sexual de los pacientes para quienes existen estudios serológicos. Por otra parte, es solo en años recientes que se ha desarrollado una prueba serológica lo suficientemente especifica par diferenciar los anticuerpos a los tipos 1 y 2 del virus del Herpes simplex (VHS) (1) lo que ha hecho posible estimar con precisión la prevalencia de la infección con el VHS de tipo 2 (VHS-2): una de lá& más importantes ETS. El presente artículo se basa en las pruebas serológicas y la información de una muestra nacionalmente representativa de las mujeres de Costa Rica. Describe la prevalencia de anticuerpos al virus del Herpes simplex tipos 1 y 2, sífilis, chlamydia, virus de inmunodeficiencia humana (HlV-1) y virus linfotrópico de células humanas-T (HTLV-1) según características demográficas, médicas y sexuales. El artículo también muestra la distribución regional de la prevalencia de anticuerpos a estos agentes.Ítem Reproductive history and breast cancer in a population of high fertility, Costa Rica, 1984-85(International Journal of Cancer, Vol. 40, no. 6, 1987) Rosero Bixby, Luis; Oberle, Mark W.; Lee, Nancy C.The relationship between breast cancer and women’s reproductive history in Costa Rica was analyzed using logistic regression methods on data from 171 breast cancer cases and 826 population-based controls aged 25-5B years. The risk of breast cancer in nulliparous women under age 45 was 3 times that for parous women in the same age group. Women over 44 years of age with a parity greater than 4 had a risk of breast cancer of 0.3 com p a red to women of the same age but with a parity of 1-4. Neither breast-feeding nor birth interval showed an overall association with breast cancer independent of parity. Women with early age a t first birth had a lower relative risk of b re a s t cancer than women aged 20-24 at first birth, but only in two subgroups—women aged 45 and over and women with parity 1-4. Women without a completed pregnancy in the last 20 years had an elevated relative risk. However, results are not conclusive because some information is probably distorted by recall errors. Declines in fertility rates in the 1960s and 1970s may result in an increase of 30% in breast cancer incidence in Costa Rica between 1980 and the year 2000, according to the relative risks found in this study. In contrast, the effect of childlessness will probably no t produce significant changes in national b re a s t cancer trends.Ítem Screening practices for cervical and breast cáncer in Costa Rica(Bull Pan Am Health Organ. v. 25, n.1,, 1991) Irwin, Kathleen L.; Oberle, Mark W.; Rosero Bixby, LuisCervical cancer and breast cancer are leading causes of cancer-related morbidity and mortality in Costa Rica. This article reports results of an evaluation of cervical and breast cancer screening practices among Costa Rican women 25 to 58 years old that was based on a nationwide 1984-1985 survey. The evaluation showed that while Pap smears were widely used to screen for cervical cancer, many women did not have their first cervical smear or gynecologic examination until age 30, and that cervical cancer screening was less common among certain high-risk groups, including women with multiple sexual partners and those with high parity. Less than half the women surveyed reported having had a breast examination by a health care provider. Utilization of both cervical cancer and breast cancer screening examinations could be increased by targeting inadequately screened high-risk women through the existing health care system.Ítem Seroepidemiology of Chlamydia in Costa Rica(Genitourinary medicine no. 66, 1990) Vetter, Kathleen M.; Barnes, R.C.; Oberle, Mark W.; Rosero Bixby, Luis; Schachter, JuluisA population-based study of the sero-epidemiology of chlamydia was performed among a nationally representative sample of 760 Costa Rican women aged 25 to 59 years. Interviews and sera collection were completed between September 1984 and February 1985. The overall seroprevalence of chlamydial antibodies among these women was 56.1%. Women 25 to 39 years of age had a seroprevalence of 51.1%, while women 40 to 59 years of age had a seroprevalence of 64.2%. Women who reported no prior sexual activity had a seroprevalence rate of 48.6%, compared with a seroprevalence rate of 80.7% among women who reported three or more lifetime sexual partners. The geometric mean titre (GMT) of seropositive women ranged from 34.4 among the women who reported no prior sexual activity to 155.0 among the women with three or more lifetime sexual partners. Sero-positivity was more consistently associated with sexual activity than with age. Women with serological evidence of past Herpes simplex virus type 2 (HSV-2) or syphilis infection were more likely to be seropositive than were women without evidence of exposure to these sexually transmitted diseases, even when controlled for age and the number of lifetime sexual partners. The seropositivity among never sexually active women indicates the probable presence of Chlamydia pneumoniae infections, while the high seroprevalence of chlamydial antibodies among the sexually active women suggests that sexually transmitted Chlamydia trachomatis infections represent a public health problem not previously quantified in Costa Rica. Further seroepidemiological and/or culture studies are warranted to determine the incidence and prevalence of sexually transmitted chlamydial infection among men and younger women.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 Susceptibilidad al tetanos y rubeola en las mujeres de Costa Rica, 1984-85(Revista Costarricense de Ciencias Médicas, vol. 9, no. 4, 1987) Ramírez, Jorge A.; Rosero Bixby, Luis; Oberle, Mark W.Se documenta por primera vez en Costa Rica, el nivel de susceptibilidad al tétanos y la rubéola en la población femenina costarricense entre los 25 y 29 años. Se encuestó a 805 de las mujeres (93%) que conformaban la muestra, de ellas el 88 por ciento (762) dio su consentimiento para la obtención de muestras de sangre para el análisis serológico. El nivel de susceptibilidad encontrado para la rubéola y el tétanos fue de 10.9 y 7.9 por ciento, respectivamente. Las mujeres susceptibles al tétanos presentaron una asociación estadísticamente significativa (p<0.05) con la edad, la educación y el estrato socioeconómico. En contraste, las susceptibles a la rubéola no presentaron ninguna asociación estadística. La entrevista oral para determinar susceptibilidad a la rubéola mostró una sensibilidad sólo del 26 por ciento, en contraposición a la del tétanos que fue de un 40 por ciento. Se discuten las medidas complementarias a los programas de vacunación ya existentes, necesarias para disminuir o eliminar los acúmulos de susceptibles en la población de mujeres costarricenses.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.