Epidemiological measures: application and interpretation in real-life scenarios according to epidemiological study designs

Frequency, association and impact measures are key concepts in clinical epidemiology; however, it has been found that a considerable proportion of health students and professionals have no knowledge of how to use or interpret them when reading a scientific paper or conducting research. This article aims to explain the main epidemiological measures, how they are used, derived and interpreted. They are approached from the perspective of each of the most frequently used types of primary quantitative research studies (randomized clinical trials, cohort studies, case-control estudies and cross-sectional studies) in order to provide the reader with the context in which they are used. Moreover, the process for calculating and interpreting each result in a real setting is explained using clinical examples for a better understanding of these concepts and in order to prevent their use from becoming just a mechanical or repetitive exercise.

Las medidas de frecuencia, asociación e impacto son conceptos fundamentales de la epidemiología clínica; sin embargo, se ha encontrado que una parte considerable de los estudiantes y de los profesionales en el área de la salud no sabe cómo usarlas ni cómo interpretarlas al leer un texto científico o al hacer una investigación. Este artículo busca explicar las principales medidas epidemiológicas, cuándo se usan, cómo se obtienen y cómo se interpretan. Se abordan desde cada tipo de estudios primarios más frecuentemente utilizados cuando se realizan investigaciones cuantitativas (ensayos clínicos aleatorizados, estudios de cohorte, casos y controles y estudios de corte transversal), con el fin de darle al lector el contexto en el cual se usan. Además, mediante ejemplos clínicos, se explica el proceso para calcular e interpretar cada resultado en un escenario real, con el fin de lograr una mayor comprensión de estos conceptos y de que su uso no sea un ejercicio mecánico o de repetición.

Exposure to armed conflict as a factor associated with very low birth weight: Case-control population study.

OBJECTIVE: To determine the association between armed conflict and very low birth wright (VLBW), which is a multifactorial etiology public health problem that includes aspects of poverty and violence. METHODS: Case-control population study matched by year of delivery conducted in Cauca, Colombia, between 2010 and 2016. Cases of VLBW, with weights between 500 and 1499 g and controls weighing between 2500 and 3999 g. Cases and controls were identified through the vital statistics registry, and exposure was determined using a multidimensional index designed by the Colombian State. Multiple gestations were excluded. Conditional logistic regression for matched data was used, adjusting for confounding variables. RESULTS: Overall, 7068 matched participants (1767 cases and 5301 controls) were included. Cases and controls had similar baseline characteristics. Participants were predominantly women in the second and third decades of life, 3222 (46%) were exposed to armed conflict, and 1902 (27%) were of African-Colombian or indigenous ethnicity. Maternal exposure to armed conflict significantly increased the odds of VLBW among women with rural birth (adjusted odds ratio [aOR] 3.86, 95% confidence interval [CI] 2.74-5.45) and inadequate prenatal care (aOR 10.38, 95% CI 8.20-13.12). CONCLUSION: Exposure to armed conflict increases the odds of VLBW neonates. This factor needs to be considered in prenatal care.