Department of Child and Adolescent Psychiatry, University of Zurich, Switzerland.
BMC Psychiatry. 2011 Apr 7;11:54. doi: 10.1186/1471-244X-11-54.
The International Multi-centre ADHD Genetics (IMAGE) project with 11 participating centres from 7 European countries and Israel has collected a large behavioural and genetic database for present and future research. Behavioural data were collected from 1068 probands with the combined type of attention deficit/hyperactivity disorder (ADHD-CT) and 1446 'unselected' siblings. The aim was to analyse the IMAGE sample with respect to demographic features (gender, age, family status, and recruiting centres) and psychopathological characteristics (diagnostic subtype, symptom frequencies, age at symptom detection, and comorbidities). A particular focus was on the effects of the study design and the diagnostic procedure on the homogeneity of the sample in terms of symptom-based behavioural data, and potential consequences for further analyses based on these data.
Diagnosis was based on the Parental Account of Childhood Symptoms (PACS) interview and the DSM-IV items of the Conners' teacher questionnaire. Demographics of the full sample and the homogeneity of a subsample (all probands) were analysed by using robust statistical procedures which were adjusted for unequal sample sizes and skewed distributions. These procedures included multi-way analyses based on trimmed means and winsorised variances as well as bootstrapping.
Age and proband/sibling ratios differed between participating centres. There was no significant difference in the distribution of gender between centres. There was a significant interaction between age and centre for number of inattentive, but not number of hyperactive symptoms. Higher ADHD symptom frequencies were reported by parents than teachers. The diagnostic symptoms differed from each other in their frequencies. The face-to-face interview was more sensitive than the questionnaire. The differentiation between ADHD-CT probands and unaffected siblings was mainly due to differences in hyperactive/impulsive symptoms.
Despite a symptom-based standardized inclusion procedure according to DSM-IV criteria with defined symptom thresholds, centres may differ markedly in probands' ADHD symptom frequencies. Both the diagnostic procedure and the multi-centre design influence the behavioural characteristics of a sample and, thus, may bias statistical analyses, particularly in genetic or neurobehavioral studies.
国际多中心注意缺陷多动障碍遗传学（IMAGE）项目有来自 7 个欧洲国家和以色列的 11 个参与中心，为当前和未来的研究收集了大量行为和遗传数据库。行为数据来自 1068 名合并型注意缺陷/多动障碍（ADHD-CT）患者和 1446 名“未选择”的兄弟姐妹。目的是分析 IMAGE 样本在人口统计学特征（性别、年龄、家庭状况和招募中心）和精神病理学特征（诊断亚型、症状频率、症状发现年龄和合并症）方面的情况。特别关注的是研究设计和诊断程序对基于症状的行为数据样本同质性的影响，以及这些数据对进一步分析的潜在影响。
诊断基于父母对儿童症状的描述（PACS）访谈和康纳斯老师问卷的 DSM-IV 项目。使用稳健的统计程序分析全样本和亚样本（所有患者）的人口统计学特征，并对基于这些数据的进一步分析进行了调整，这些程序包括基于修剪均值和有偏方差的多向分析以及引导法。
参与中心之间的年龄和患者/兄弟姐妹比例存在差异。中心之间的性别分布没有显著差异。年龄和中心之间存在显著的交互作用，表现为注意力不集中症状的数量，但多动症状的数量没有差异。父母报告的 ADHD 症状频率高于教师。诊断症状的频率不同。面对面访谈比问卷更敏感。ADHD-CT 患者与未受影响的兄弟姐妹之间的区别主要归因于多动/冲动症状的差异。
尽管根据 DSM-IV 标准采用了基于症状的标准化纳入程序，并确定了症状阈值，但各中心在患者的 ADHD 症状频率方面可能存在显著差异。诊断程序和多中心设计都会影响样本的行为特征，从而可能对统计分析产生偏差，特别是在遗传或神经行为研究中。
