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. 2017 Jul 3;17(1):239.
doi: 10.1186/s12888-017-1401-4.

Dementia ascertainment using existing data in UK longitudinal and cohort studies: a systematic review of methodology

Ruth A Sibbett  1   2 , Tom C Russ  3   4   5   6 , Ian J Deary  3   4   7 , John M Starr  3   4
Affiliations

Dementia ascertainment using existing data in UK longitudinal and cohort studies: a systematic review of methodology

Ruth A Sibbett et al. BMC Psychiatry. .

Abstract

Background: Studies investigating the risk factors for or causation of dementia must consider subjects prior to disease onset. To overcome the limitations of prospective studies and self-reported recall of information, the use of existing data is key. This review provides a narrative account of dementia ascertainment methods using sources of existing data.

Methods: The literature search was performed using: MEDLINE, EMBASE, PsychInfo and Web of Science. Included articles reported a UK-based study of dementia in which cases were ascertained using existing data. Existing data included that which was routinely collected and that which was collected for previous research. After removing duplicates, abstracts were screened and the remaining articles were included for full-text review. A quality tool was used to evaluate the description of the ascertainment methodology.

Results: Of the 3545 abstracts screened, 360 articles were selected for full-text review. 47 articles were included for final consideration. Data sources for ascertainment included: death records, national datasets, research databases and hospital records among others. 36 articles used existing data alone for ascertainment, of which 27 used only a single data source. The most frequently used source was a research database. Quality scores ranged from 7/16 to 16/16. Quality scores were better for articles with dementia ascertainment as an outcome. Some papers performed validation studies of dementia ascertainment and most indicated that observed rates of dementia were lower than expected.

Conclusions: We identified a lack of consistency in dementia ascertainment methodology using existing data. With no data source identified as a "gold-standard", we suggest the use of multiple sources. Where possible, studies should access records with evidence to confirm the diagnosis. Studies should also calculate the dementia ascertainment rate for the population being studied to enable a comparison with an expected rate.

Keywords: Dementia; Research design and methodology.

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Conflict of interest statement

Ethics approval and consent to participate

No ethical approval required.

Consent for publication

Not applicable.

Competing interests

This review included previous works by some of the authors.

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Figures

Fig. 1
Fig. 1
Study Flow Design
Fig. 2
Fig. 2
Sources of Existing Data for all Included Articles
See this image and copyright information in PMC

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