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Diagnostic Test Accuracy Protocol

IQCODE for the diagnosis of Alzheimer’s disease dementia and other dementias within a community setting

  1. Terry J Quinn1,*,
  2. Rupert McShane2,
  3. Patricia Fearon3,
  4. Camilla Young3,
  5. Anna Noel-Storr4,
  6. David J Stott3

Editorial Group: Cochrane Dementia and Cognitive Improvement Group

Published Online: 12 SEP 2012

Assessed as up-to-date: 1 JUL 2012

DOI: 10.1002/14651858.CD010079

How to Cite

Quinn TJ, McShane R, Fearon P, Young C, Noel-Storr A, Stott DJ. IQCODE for the diagnosis of Alzheimer’s disease dementia and other dementias within a community setting (Protocol). Cochrane Database of Systematic Reviews 2012, Issue 9. Art. No.: CD010079. DOI: 10.1002/14651858.CD010079.

Author Information

  1. 1

    University of Glasgow, Cardiovascular and Medical Sciences, Glasgow, UK

  2. 2

    University of Oxford, Nuffield Department of Medicine, Oxford, Oxfordshire, UK

  3. 3

    University of Glasgow, Academic Section of Geriatric Medicine, Glasgow, UK

  4. 4

    Nuffield Department of Medicine, University of Oxford, Cochrane Dementia and Cognitive Improvement Group, Oxford, UK

*Terry J Quinn, Cardiovascular and Medical Sciences, University of Glasgow, Walton Building, Glasgow Royal Infirmary, Glasgow, G4 0SF, UK.

Publication History

  1. Publication Status: New
  2. Published Online: 12 SEP 2012


This is not the most recent version of the article. View current version (10 APR 2014)



  1. Top of page
  2. Abstract

This is the protocol for a review and there is no abstract. The objectives are as follows:

To determine the diagnostic accuracy of the informant based questionnaire IQCODE, in detection of all cause (undifferentiated) dementia in community-dwelling adults. 

(Where data are available) we will describe the following.

  1. The diagnostic accuracy of IQCODE at various pre-specified thresholds. We recognize 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.  If data are available for IQCODE scores not in the pre-specified list, we will describe all IQCODE scores greater than 3.6 or less than 3.3 together. 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 maximize available data for review.
  2. Accuracy of IQCODE for diagnosis of the commonest specific dementia subtype - Alzheimer’s dementia.
  3. Effects of heterogeneity (see below) on the reported diagnostic accuracy of IQCODE.

The focused study question, restricting review to cross-sectional studies in a community setting is designed to remove potential heterogeneity relating to study design and setting. Other sources of heterogeneity in dementia studies such as treatment; intervention or duration of follow-up are not applicable to a cross-sectional study in an unselected population and will not be considered outwith inclusion/exclusion criteria. The properties of a tool describe behaviour of the instrument under particular circumstances. Thus for our assessment of potential sources of heterogeneity (where data allow), we will collect data on features of the study population namely age; features of the index test namely language of administration and IQCODE format; features of the reference standard namely diagnostic criteria used and diagnostic methodology. Analysis of heterogeneity will be performed by adding these prespecified co-variates to the bivariate model. Operational definitions are given in the section Data collection and analysis and Investigations of heterogeneity below.