Hammar N, Norell S E
Department of Epidemiology, Karolinska Institutet, Stockholm, Sweden.
Int J Epidemiol. 1991 Sep;20(3):621-7. doi: 10.1093/ije/20.3.621.
A cohort of subjects born 1908 to 1925 answered a questionnaire on dietary habits in 1967 (original information). Of the cases of colorectal cancer that were diagnosed in this cohort 1968-1983, 50 were still alive in 1987. A total of 150 controls were selected as a stratified (age, sex) random sample of those who did not have a colorectal cancer. In 1987, the cases and controls were asked to fill in a questionnaire on dietary habits in 1967 (retrospective information) as well as on their current dietary habits. The questions were identical and used to compare retrospective and original information on diet among cases and controls, taking into account any changes in dietary habits during the intervening period. Cases and controls usually had a similar tendency to overestimate or underestimate their previous food intake. For both cases and controls, the tendency to overestimate previous intake was closely related to an increase in consumption during the intervening period and vice versa. Among those subjects who had not altered their consumption during the intervening period, there was usually a rather good agreement between the retrospective and original information. This was true for the cases as well as for the controls. For certain food items, the results suggest that the use of retrospective information would introduce a differential misclassification. In order to avoid or reduce a differential misclassification introduced by differences between cases and controls in changes in consumption due to the disease under study, it may be advisable to interview the cases as soon as possible after diagnosis or even at the time of preliminary diagnosis.
一组出生于1908年至1925年的受试者于1967年回答了一份关于饮食习惯的问卷（原始信息）。在该队列中1968 - 1983年被诊断出的结直肠癌病例中，有50例在1987年仍然存活。总共选取了150名对照，作为没有患结直肠癌者的分层（年龄、性别）随机样本。1987年，病例组和对照组被要求填写一份关于1967年饮食习惯的问卷（回顾性信息）以及他们当前的饮食习惯。问题是相同的，用于比较病例组和对照组关于饮食的回顾性信息和原始信息，同时考虑到在此期间饮食习惯的任何变化。病例组和对照组通常在高估或低估他们之前食物摄入量方面有相似的倾向。对于病例组和对照组来说，高估之前摄入量的倾向与在此期间摄入量的增加密切相关，反之亦然。在那些在此期间摄入量没有改变的受试者中，回顾性信息和原始信息之间通常有相当好的一致性。病例组和对照组都是如此。对于某些食物项目，结果表明使用回顾性信息会导致差异性错误分类。为了避免或减少由于所研究疾病导致的病例组和对照组在摄入量变化方面的差异所引入的差异性错误分类，可能建议在诊断后尽快甚至在初步诊断时就对病例进行访谈。
