This is a protocol for a Cochrane Review (Diagnostic test accuracy). The objectives are as follows:
To determine the diagnostic accuracy of the informant-based questionnaire IQCODE, in detection of all-cause (undifferentiated) dementia in adults presenting to secondary-care services.
Where data are available we will describe the following:
The diagnostic accuracy of IQCODE at various prespecified thresholds. We recognise that various thresholds or cut-off scores have been used to define IQCODE screen positive states. We will describe the properties of IQCODE for the following cut-off scores (rounded where necessary): 3.6; 3.5; 3.4; 3.3. These thresholds have been chosen to represent the range of cut-offs that are commonly used in practice and research; we have been inclusive in our choice of cut-off to maximise available data for review.
Accuracy of IQCODE for diagnosis of the commonest specific dementia subtype - Alzheimer’s dementia.
Effects of heterogeneity (see below) on the reported diagnostic accuracy of IQCODE. Potential sources of heterogeneity that we will explore include: age of cohort; case mix of cohort; reason for hospital consultation (dichotomised as 'memory' or 'non-memory' services); technical features of IQCODE; method of dementia diagnosis.