Rasmussen Sonja A, Olney Richard S, Holmes Lewis B, Lin Angela E, Keppler-Noreuil Kim M, Moore Cynthia A
National Center on Birth Defects and Developmental Disabilities, Centers for Disease Control and Prevention, Atlanta, Georgia 30341, USA.
Birth Defects Res A Clin Mol Teratol. 2003 Mar;67(3):193-201. doi: 10.1002/bdra.10012.
Previous studies have suggested that etiologic heterogeneity may complicate epidemiologic analyses designed to identify risk factors for birth defects. Case classification uses knowledge of embryologic and pathogenetic mechanisms to make case groups more homogeneous and is important to the success of birth defects studies.
The goal of the National Birth Defects Prevention Study (NBDPS), an ongoing multi-site case-control study, is to identify environmental and genetic risk factors for birth defects. Information on environmental risk factors is collected through an hour-long maternal interview, and DNA is collected from the infant and both parents for evaluation of genetic risk factors. Clinical data on infants are reviewed by clinical geneticists to ensure they meet the detailed case definitions developed specifically for the study. To standardize the methods of case classification for the study, an algorithm has been developed to guide NBDPS clinical geneticists in this process.
Methods for case classification into isolated, multiple, and syndrome categories are described. Defects considered minor for the purposes of case classification are defined. Differences in the approach to case classification for studies of specific defects and of specific exposures are noted.
The case classification schema developed for the NBDPS may be of value to other clinicians working on epidemiologic studies of birth defects etiology. Consideration of these guidelines will lead to more comparable case groups, an important element of careful studies aimed at identifying risk factors for birth defects.
先前的研究表明，病因异质性可能会使旨在确定出生缺陷危险因素的流行病学分析变得复杂。病例分类利用胚胎学和发病机制方面的知识，使病例组更加同质化，这对出生缺陷研究的成功至关重要。
正在进行的多中心病例对照研究——国家出生缺陷预防研究（NBDPS）的目标是确定出生缺陷的环境和遗传危险因素。通过长达一小时的产妇访谈收集环境危险因素信息，并从婴儿及其父母双方采集DNA，以评估遗传危险因素。临床遗传学家会审查婴儿的临床数据，以确保他们符合专门为该研究制定的详细病例定义。为了规范该研究的病例分类方法，已开发出一种算法，以指导NBDPS临床遗传学家进行这一过程。
描述了将病例分类为孤立性、多发性和综合征类别的方法。定义了在病例分类中被视为轻微的缺陷。指出了针对特定缺陷和特定暴露的研究在病例分类方法上的差异。
为NBDPS开发的病例分类模式可能对其他从事出生缺陷病因流行病学研究的临床医生有价值。考虑这些指南将导致病例组更具可比性，这是旨在确定出生缺陷危险因素的严谨研究的一个重要因素。
