Diagnostic tools for alzheimer's disease dementia and other dementias: an overview of diagnostic test accuracy (DTA) systematic reviews

Abstract

Background: Dementia includes a group of neurodegenerative disorders characterized by progressive loss of cognitive function and a decrease in the ability to perform activities of daily living. Systematic reviews of diagnostic test accuracy (DTA) focus on how well the index test detects patients with the disease in terms of figures such as sensitivity and specificity. Although DTA reviews about dementia are essential, at present there is no information about their quantity and quality.

Methods: We searched for DTA reviews in MEDLINE (1966-2013), EMBASE (1980-2013), The Cochrane Library (from its inception until December 2013) and the Database of Abstracts of Reviews of Effects (DARE). Two reviewers independently assessed the methodological quality of the reviews using the AMSTAR measurement tool, and the quality of the reporting using the PRISMA checklist. We describe the main characteristics of these reviews, including basic characteristics, type of dementia, and diagnostic test evaluated, and we summarize the AMSTAR and PRISMA scores.

Results: We selected 24 DTA systematic reviews. Only 10 reviews (41.6%), assessed the bias of included studies and few (33%) used this information to report the review results or to develop their conclusions Only one review (4%) reported all methodological items suggested by the PRISMA tool. Assessing methodology quality by means of the AMSTAR tool, we found that six DTA reviews (25%) pooled primary data with the aid of methods that are used for intervention reviews, such as Mantel-Haenszel and separate random-effects models (25%), while five reviews (20.8%) assessed publication bias by means of funnel plots and/or Egger's Test.

Conclusions: Our assessment of these DTA reviews reveals that their quality, both in terms of methodology and reporting, is far from optimal. Assessing the quality of diagnostic evidence is fundamental to determining the validity of the operating characteristics of the index test and its usefulness in specific settings. The development of high quality DTA systematic reviews about dementia continues to be a challenge.

Figure 1

Flowchart of the systematic search.

Figure 2

PRISMA items reported by DTA reviews about dementia. Notes: Item 1 = Identify the report as a systematic review; Item 2 = Provide a structured summary; Item 3 = Describe the rationale of the review; Item 4 = Provide an explicit statement of questions being addressed; Item 5 = Indicate if a review protocol exists; Item 6 = Specify study characteristics; Item 7 = Describe all information sources in the search and date last searched; Item 8 = Present full electronic search strategy; Item 9 = State the process for selecting studies; Item 10 = Describe method of data extraction; Item 11 = List and define all variables for which data were sought; Item 12 = Describe methods used for assessing risk of bias of individual studies; Item 13 = State the principal summary measures; Item 14 = Describe the methods of handling data and combining results; Item 15 = Specify any assessment of risk of bias that may affect the evidence; Item 16 = Describe methods of additional analyses; Item 17 = Give numbers of studies screened, assessed for eligibility, and included in the review; Item 18 = For each study, present characteristics for which data were extracted; Item 19 = Present data on risk of bias of each study; Item 20 = For all outcomes present simple summary data, effect estimates and confidence intervals; Item 21 = Present the main results of the review; Item 22 = Present results of any assessment of risk of bias across studies; Item 23 = Provide results of additional analyses; Item 24 = Summarize the main findings; Item 25 = Discuss limitations at study and outcome level and at review-level; Item 26 = Provide a general interpretation of the results and implications for future research; Item 27 = Describe sources of funding for the systematic review.

Figure 3

Results of AMSTAR assessment- DTA systematic reviews about dementia. Notes: Item 1 = Priori design; Item 2 = Duplicate study selection/data extraction; Item 3 = Comprehensive literature search; Item 4 = inclusion criterion -status of publication; Item 5 = list of studies provided; Item 6 = characteristics of the included studies provided; Item 7 = scientific quality of the included studies assessed & documented; Item 8 = scientific quality of the included studies in formulating conclusions; Item 9 = methods used to combine the findings of studies appropriate; Item 10 = publication bias assessed; Item 11 = conflict of interest stated.