Técnicas estadísticas para identificar posibles relaciones bivariadas / Statistical techniques for possible identification on bivariate relations

Introducción: La mayoría de los problemas en la investigación biomédica son de naturaleza causal. El análisis en estos estudios debe comenzar por la búsqueda de asociación entre las variables que representan la causa y el efecto y solo si la asociación es significativa, continuará el análisis de inferencia causal. Objetivo: Sistematizar las diferentes técnicas estadísticas que verifican una relación bivariada según el tipo de variable. Métodos: Se realizó una revisión bibliográfica exhaustiva sobre el tema en las bases de datos biomédicas alojadas en la Internet. Se organizó el contenido por subtemas y se elaboró un material con una síntesis crítica de los aspectos más importantes, en el cual se plasmó además la experiencia de las autoras. Resultados: Se expone, según tipo de variables, información básica de los coeficientes, pruebas de hipótesis y gráficos empleados en cada caso, las medidas de asociación para estudiar el riesgo, los atributos que aseguran la validez de una asociación, el azar y el sesgo como los errores que pudieran cometerse en el proceso de investigación y que pueden invalidar la existencia de una asociación. También se presenta la forma de analizar la asociación en el análisis estadístico implicativo. Conclusiones: El conocimiento de los estadísticos para verificar una relación entre variables y la selección de técnicas estadísticas es esencial para llevar a cabo el proceso inicial de inferencia causal(AU)

Introduction: Most of the problems in biomedical research are of causal nature. The analysis of these studies should begin with the search for an association between the variables that represent the cause and the effect, and only if the association is significant will the causal inference analysis continue. Objective: To systematize the different statistical techniques that verify a bivariate relationship according to the type of variable. Methods: An exhaustive bibliographic review on the subject was carried out in the biomedical databases hosted in the Internet. The content was organized by sub-topics and a material with a critical synthesis of the most important aspects was elaborated, in which the experience of the authors was also expressed. Results: According to the type of variables, we have presented basic information about the coefficients, hypothesis tests, and graphs used in each case, the association measures to study risk, the features that ensure the validity of an association; chance and bias are also exposed as the mistakes that could be made in the investigation process and that could invalidate the existence of an association. The way of analyzing the association in the implicative statistical analysis is also presented. Conclusions: The knowledge of statisticians to verify a relationship between variables and the selection of statistical techniques is essential for carrying out the initial process of causal inference(AU)

Association between reproductive factors and breast cancer in an urban set up at central India: A case-control study.

Background: Epigenetic changes, geography and environmental factors do surpass the genetic factors in the development of breast cancer. This study investigates the association of reproductive factors with the breast cancer in this context. Objective: To detect the association of reproductive risk factors with breast cancer in an urban set up at central India. Study Design: Matched paired community-based case-control study. Materials and Methods: The study was conducted for a period of a year from October 2008 to August 2009 in Bhopal (MP). Demographic data and reproductive risk factor related information were collected using structured questionnaire. Data analysis was done by Epi-info and SPSS 16. Results: History of using oral contraceptive pills (OR = 3.02, 95% CI: 1.28-7.11), history of not having breastfeeding (OR = 3.62, 95% CI: 1.29-10.16) and family history of breast cancer (OR = 3.98, 95%CI: 1.06-14.826) were associated significantly with the occurrence of breast cancer in multivariate analysis. Conclusions: The findings of the present study suggests that positive family history of breast cancer and history of using OCP may be the epigenetic factors promoting the occurrence of breast cancer while breastfeeding reduces the possibility of acquiring breast cancer.