Detecting dementia: how hit and miss is this questionnaire?

Evidently Cochrane: By Sarah Chapman // December 4, 2015

In the UK, 9.9 million people are aged over 65 and it has been estimated that around 6.6% have dementia; in the over 85s, this may be as high as 50%. Dementia has been identified as a national priority in health and social care and recent guidelines have emphasized early diagnosis to help with planning and management, though ‘screening’ for dementia remains the subject of debate.

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Image source: Evidently Cochrane

A questionnaire to identify possible dementia

Currently, less than half those with dementia will be diagnosed as having it. There are lots of different ways of assessing people for possible dementia and no clear agreement about the best way to do it. One approach is to ask someone who knows the person about changes they’ve observed and a questionnaire that is commonly used for this purpose is the Informant Questionnaire on Cognitive Decline in the Elderly (IQCODE).

A team led by Dr Terry Quinn at the Cochrane Dementia and Cognitive Improvement Group has conducted a series of Cochrane reviews to find out what research can tell us about the accuracy of the IQCODE, used in different settings, for identifying possible dementia. A diagnosis of dementia can’t be made using the IQCODE alone, but this questionnaire can be used to flag up the need for further assessment or to help with a diagnosis along with other investigations.

The reviewers found that although the accuracy of the IQCODE is in a range that many would consider reasonable, in this population its use is likely to result in a large number of people being wrongly assessed as likely to have dementia and a large number of people who do have dementia being missed.

So out of a population of 100, it’s wrong for 15 of them.

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Image source: Evidently Cochrane

Read the full commentary via Evidently Cochrane

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