Fayers P M, Hand D J, Bjordal K, Groenvold M
Unit for Epidemiology and Clinical Research, Faculty of Medicine, Norwegian University of Science and Technology, Trondheim, Norway.
Qual Life Res. 1997 Jul;6(5):393-406. doi: 10.1023/a:1018491512095.
Quality of Life (QOL) questionnaires contain two different types of items. Some items, such as assessments of symptoms of disease, may be called causal indicators because the occurrence of these symptoms can cause a change in QOL. A severe state of even a single symptom may suffice to cause impairment of QOL, although a poor QOL need not necessarily imply that a patient suffers from all the symptoms. Other items, for example anxiety and depression, can be regarded as effect indicators which reflect the level of QOL. These indicators usually have a more uniform relationship with QOL, and therefore a patient with poor QOL is likely to have low scores on all effect indicators. In extreme cases it may seem intuitively obvious which items are causal and which are effect indicators, but often it is less clear. We propose a model which includes these two types of indicators and show that they behave in markedly different ways. Formal quantitative methods are developed for distinguishing them. We also discuss the impact of this distinction upon instrument validation and the design and analysis of summary subscales.
生活质量（QOL）问卷包含两种不同类型的项目。一些项目，如对疾病症状的评估，可称为因果指标，因为这些症状的出现会导致生活质量的变化。即使单一症状的严重状态也可能足以导致生活质量受损，尽管生活质量差不一定意味着患者患有所有症状。其他项目，例如焦虑和抑郁，可被视为反映生活质量水平的效应指标。这些指标通常与生活质量有更一致的关系，因此生活质量差的患者在所有效应指标上的得分可能较低。在极端情况下，哪些项目是因果指标，哪些是效应指标，直观上可能很明显，但通常情况并非如此清晰。我们提出了一个包含这两种类型指标的模型，并表明它们的行为方式明显不同。我们开发了正式的定量方法来区分它们。我们还讨论了这种区分对工具验证以及汇总子量表的设计和分析的影响。
