Poser C M, Benedikz J, Hibberd P L
Department of Neurology, Harvard Medical School, Boston, MA 02215.
J Neurol Sci. 1992 Sep;111(2):143-52. doi: 10.1016/0022-510x(92)90062-p.
The epidemiology of multiple sclerosis (MS) is characterized by the fact that there is an uneven distribution of the disease throughout the world. The two most commonly used indices of its frequency are the incidence and prevalence rates. The incidence rate reflects, to a great extent, the influence of environmental factors in triggering the clinical manifestations of the disease, if it is based upon the actual date of the initiation of symptoms, rather than the date of diagnosis. The prevalence rate is currently based on the date of diagnosis and includes all MS patients who are alive on a particular date, without regard to their ethnic origin, the site and the duration of residence or any other factors that may have influenced the acquisition of the disease. We propose that in order to make the concept of the prevalence rate possibly more meaningful, the term should refer, retrospectively, to all patients whose symptoms eventually led to the diagnosis of MS, even though the diagnosis was not yet established on an earlier prevalence day. In addition, only patients of the same ethnic background who have spent their prepuberal years in the geographical area under study should be included. We are calling this measure the onset-adjusted prevalence rate. Another problem encountered in epidemiological studies of MS relates to the common practice of adjusting prevalence data obtained for age and sex in one area to what is referred to as a "standard" American (or world) population, groups of great ethnic and age diversity. It is also curious that in many studies the bases for comparison of populations are census data obtained many years previously. We suggest that age and sex adjustment should be applied only to similar ethnic groups born and raised under different environmental conditions. We believe that data obtained by calculating an onset-adjusted prevalence rate restricted to a homogeneous group of patients sharing the same environment during the prepuberal years may provide valuable etiological clues.
多发性硬化症（MS）的流行病学特征在于，该疾病在全球的分布并不均匀。其发病率和患病率是最常用的两个疾病频率指标。如果发病率是基于症状开始的实际日期而非诊断日期，那么在很大程度上，它反映了环境因素在引发该疾病临床表现方面的影响。患病率目前是基于诊断日期，包括在特定日期存活的所有MS患者，而不考虑其种族、居住地点和时长或任何其他可能影响疾病发生的因素。我们建议，为了使患病率这一概念可能更有意义，该术语应追溯性地指代所有其症状最终导致MS诊断的患者，即使在更早的患病率统计日尚未确诊。此外，仅应纳入在研究地理区域度过青春期前岁月的相同种族背景的患者。我们将此指标称为发病调整患病率。在MS的流行病学研究中遇到的另一个问题涉及一种常见做法，即将在一个地区获得的按年龄和性别调整的患病率数据调整为所谓的“标准”美国（或世界）人群数据，这些人群具有很大的种族和年龄差异。同样奇怪的是，在许多研究中，人群比较的依据是多年前获得的人口普查数据。我们建议年龄和性别调整仅应适用于在不同环境条件下出生和成长的相似种族群体。我们认为，通过计算仅限于在青春期前岁月处于相同环境的同质患者群体的发病调整患病率所获得的数据，可能会提供有价值的病因线索。
