Preventing mother-to-child HIV transmission in the new millennium: the challenge of breast feeding.

Short courses of antiretroviral drugs have greatly enhanced the prospect of reducing mother-to-child HIV transmission. Yet transmission by breast feeding clouds hopes for this seemingly simple intervention. We revisit mathematical models to assess the competing risks associated with feeding by breast vs. formula. These indicate that, in the less developed world where the HIV epidemic predominates, neither option, unmodified, offers a reasonable choice for HIV-positive women. Where infant mortality rates are greater than about 40 per 1000 live births, if formula were made available to HIV-infected women only, the excess number of deaths that would result from formula use would be approximately the same or greater than the number of HIV infections that might be prevented. Only at lower infant mortality rates, less than about 40 per 1000, is the risk greater on the breast. There are thus no good grounds for the total avoidance of breast feeding under all conditions. Research to develop and test safer infant feeding alternatives is an urgent priority. On the one hand, ways to reduce HIV transmission while preserving breast feeding, as exclusive breast feeding could do, need to be fully tested. On the other hand, ways to reduce non-HIV morbidity and mortality associated with formula feeding, as educational or sanitary interventions could do, equally need testing. With either approach, a necessary foundation for implementing all the core components of preventing mother-to-child HIV transmission is competent counselling for mothers. Innovative approaches are needed to mobilise and train effective counsellors among health care workers and, as appropriate, community members.

Risk of cranial ultrasound abnormalities in very-low-birth-weight infants conceived with assisted reproductive techniques.

OBJECTIVE: To evaluate risks of cranial ultrasound abnormalities among very-low-birth-weight (VLBW) infants conceived with fertility therapy (ovulation induction only or with assisted reproductive techniques [ART]) and of multiple gestation pregnancies. STUDY DESIGN: The incidences of cranial ultrasound abnormalities in 1473 VLBW infants conceived with and without fertility therapy and born of multiple versus singleton pregnancies were compared, using logistic regression models. RESULTS: Infants conceived with ART were less likely to have intraventricular hemorrhage (IVH). Twins and triplets had risks of cranial ultrasound abnormalities similar to those of singletons. Twins and triplets conceived with ART were at lower risk of IVH. CONCLUSION: VLBW infants conceived with ART do not appear to be at increased risk of cranial ultrasound abnormalities. Likewise, twins and triplets were not at increased risk of these abnormalities.

Origins and early development of the case-control study: Part 2, The case-control study from Lane-Claypon to 1950.

The first modern case-control study was Janet Lane-Claypon's study of breast cancer in 1926, but the design was used only sporadically in medicine and the social sciences until 1950, when four published case-control studies linked smoking and lung cancer. These 1950 studies synthesized the essential elements of the case-control comparison, produced a conceptual shift within epidemiology, and laid the foundation for the rapid development of the case-control design in the subsequent half century.

Origins and early development of the case-control study: Part 1, Early evolution.

This paper traces the origins and early development of the case-control study, focusing on its evolution in the 19th and early 20th century. As with other forms of clinical investigation, the case-control study emerged from practices that originally belonged to the realm of patient care. This form of disease investigation can be viewed as the knitting together of medical concepts (caseness, disease etiology, and a focus on the individual)--and medical procedures (anamnesis, grouping of cases into series; and comparisons of the diseased and the healthy)--that are of ancient origin, but which were seldom brought together until the 20th century. The analytic form of the case-control study can be found in 19th century medical literature, but did not appear to be viewed as a special or distinct methodology. A number of clinical investigations, and several sociological studies, in the first half of this century can be described as case-control studies, the most fully developed of which was Janet Lane-Claypon's 1926 study of breast cancer.

Conceptos y estrategias en epidemiología: el pensamiento causal en las ciencias de la salud / Concepts and strategies in epidemiology: the causal thinking in health sciences

La temática del libro es enteramente metodológica. "La obra está dirigida a estudiantes de epidemiología y ciencias sociales aplicadas, medicina, servicios de salud y salud pública en general. proporciona conceptos prácticos con los cuales es posible interpretar las influencias ambientales sobre la salud. El principal objetivo del libro consiste en desarrollar modelos causales en una forma que fomente la comprensión de las relaciones entre los estados de salud y medio. Estos modelos son para usarse. Para que sean eficaces, deben facilitar la búsqueda de nuevos conocimientos sobre las causas de enfermedad. La profundidad de esta búsqueda depende de la solidez del diseño de la investigación y del análisis riguroso; en este libro se presta más atención al campo del análisis. El libro se divide en dos secciones principales. La primera rastrea la evolución de los conceptos de causa en las ciencias de la salud, el propósito de esto es mostrar que los conceptos son tan efímeros como la historia. La segunda sección describe procedimientos para usar modelos causales a fin de descubrir causas; se comentan cinco estrategias amplias, mismas que consisten en: la primera, simplificación de las condiciones de observación; la segunda y la tercera, detección de variables extrañas y la elaboración de variables; la cuarta, aplicación de nociones de probabilidad y, la quinta que ayuda a la interpretar los resultados del análisis" (AU). Los apartados del libro son: Prefacio. I) Límites de la epidemiología. II) Evolución de los conceptos en epidemiología. III) Agente, huésped y sistema ambiental y ecológico. IV) Lógica de las causas múltiples. V) Sistemas y niveles de organización. VI) Procedimientos para establecer asociaciones causales. VII) Simplificación de las condiciones de observación. VIII) Detección de factores extraños en modelos causales. IX) Elaboración de relaciones entre variables. X) Aplicación de nociones de probabilidad. XI) Criterios de juicio