Division of Nephrology and Hypertension, 1st Department of Internal Medicine, AHEPA Hospital, School of Medicine, Aristotle University of Thessaloniki, Thessaloniki, Greece.
Epidemiology Department, High Institute of Public Health-Alexandria University, Alexandria, Egypt.
Nephrology (Carlton). 2021 Jun;26(6):501-505. doi: 10.1111/nep.13861. Epub 2021 Feb 17.
Ecological studies are observational studies commonly used in public health research. The main characteristic of this study design is that the statistical analysis is based on pooled (i.e., aggregated) rather than on individual data. Thus, patient-level information such as age, gender, income and disease condition are not considered as individual characteristics but as mean values or frequencies, calculated at country or community level. Ecological studies can be used to compare the aggregated prevalence and incidence data of a given condition across different geographical areas, to assess time-related trends of the frequency of a pre-defined disease/condition, to identify factors explaining changes in health indicators over time in specific populations, to discriminate genetic from environmental causes of geographical variation in disease, or to investigate the relationship between a population-level exposure and a specific disease or condition. The major pitfall in ecological studies is the ecological fallacy, a bias which occurs when conclusions about individuals are erroneously deduced from results about the group to which those individuals belong. In this paper, by using a series of examples, we provide a general explanation of the ecological studies and provide some useful elements to recognize or suspect ecological fallacy in this type of studies.
生态研究是公共卫生研究中常用的观察性研究。这种研究设计的主要特点是统计分析基于汇总（即聚合）数据，而不是个体数据。因此，患者层面的信息，如年龄、性别、收入和疾病状况，不作为个体特征，而是作为在国家或社区层面计算的平均值或频率。生态研究可用于比较不同地理区域特定疾病的汇总患病率和发病率数据，评估特定疾病/状况的频率随时间的变化趋势，识别特定人群中随时间变化的健康指标变化的原因，区分疾病的地理变异中遗传和环境因素，或调查人群暴露水平与特定疾病或状况之间的关系。生态研究的主要缺陷是生态谬误，这是一种当从个体所属的群体结果错误推断个体结论时发生的偏差。在本文中，我们通过一系列实例，对生态研究进行了一般性解释，并提供了一些有用的元素，以识别或怀疑此类研究中的生态谬误。
