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Does this patient have dementia? |
Holsinger T, Deveau J, Boustani M, Williams J W |
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CRD summary This review assessed the accuracy of brief cognitive screening instruments for the diagnosis of dementia in primary care. The authors concluded that there are many such instruments and that no single instrument is ideal for all settings. Limitations in the literature search and failure to consider study quality in the synthesis mean that these findings should be interpreted with caution. Authors' objectives To evaluate the practicality and accuracy of brief cognitive screening instruments for the diagnosis of dementia in primary care. Searching MEDLINE and PsycINFO were searched from January 2000 to April 2006. Two previous reviews assessed studies published before this (see Other Publications of Related Interest nos.1-2), so this review (and abstract) only focuses on studies published since 2000. The search terms, which were reported, included a diagnostic filter. The review was limited to English language studies. Study selection Study designs of evaluations included in the reviewInclusion criteria were not defined in terms of the study design. Specific interventions included in the reviewStudies of screening instruments that can be used in primary care were eligible for inclusion. Studies that evaluated imaging, laboratory or physiological tests were excluded. Twenty-five screening instruments were included: eighteen were completed by patients, three by informants, and four by patients and informants. The instruments assessed a range of cognitive functions which included memory (orientation, registration recall, remote/over learned memory), praxis/visuospatial, aphasia/verbal fluency, attention, abstraction and executive functioning/functional status. The time to administer the instruments ranged from 1 to 2 to 20 to 30 minutes. Reference standard test against which the new test was comparedStudies that used an acceptable reference standard for the diagnosis of dementia were eligible for inclusion. Details of reference standards considered acceptable or used in the included studies were not reported. Participants included in the reviewStudies of patients aged over 60 years were eligible for inclusion. Studies conducted in in-patient or nursing home populations were excluded, as were those conducted solely in a memory disorder clinic population without an adequate control group. Studies that evaluated populations whose median education was less than 6 years were also excluded. Outcomes assessed in the reviewInclusion criteria were not defined in terms of the outcomes. The outcomes reported in the review were positive and negative likelihood ratios (LR+ and LR-, respectively). How were decisions on the relevance of primary studies made?The authors did not state how the papers were selected for the review, or how many reviewers performed the selection. Assessment of study quality Two reviewers independently assessed studies for methodological quality based on criteria developed by the U.S. Preventive Services Task Force. These included sample size, participant selection, reference standard, blinded application of the reference standard, and independence of reference standard. Any disagreements were resolved through referral to a third reviewer. Studies were considered to be 'good quality' if they were conducted in a community or primary care setting and if the intact instrument was administered independently and blindly to a random or consecutive sample. 'Fair quality' studies failed to meet at least one of the criteria for good quality and had no critical flaw that was considered to invalidate results. All other studies were 'poor quality'. Data extraction The data were extracted as 2x2 tables of test performance and used to calculate the sensitivity, specificity, LR+ and LR-. The authors did not state how many reviewers performed the data extraction. Methods of synthesis How were the studies combined?A meta-analysis was not conducted; instead median and ranges in LRs were reported. How were differences between studies investigated?Differences between the studies were not formally investigated but were discussed. Results of the review Twenty-nine studies reporting 42 test evaluations were included (the number of participants was not reported).
Three studies were judged to be of a good quality and the remaining 26 studies were fair quality. Five studies applied the reference standard to less than 50% of the participants. Eight studies used a diagnostic case-control design. In 8 studies the screening instrument was not independent of the reference standard, and in 8 studies the screening instrument was not administered as an intact instrument.
Mini-Mental State Examination (11 studies): thresholds ranged from 23 to 25, the median LR+ was 6.3 (range: 3.4 to 47) and the median LR- was 0.19 (range: 0.06 to 0.37).
Brief instruments (15 studies): a range of instruments was evaluated; most were only evaluated in single studies. The LR+ ranged from 1.2 to 47 and the LR- from 0.06 to 0.63. The most promising instruments were the memory impairment screen (LR+ 33, 95% confidence interval, CI: 15, 72; LR- 0.08, 95% CI: 0.02, 0.3) and the 7-minute screen (LR+ 47, 95% CI: 3, 730; LR- 0.09, 95% CI: 0.01, 0.59), but these were only evaluated in single studies.
Comprehensive instruments (7 studies): three instruments were evaluated. The median LR+ was 8.9 (range: 3.1 to 17) and the median LR- was 0.12 (range: 0.01 to 0.25).
Instruments for special situations (9 studies): seven instruments were evaluated; all but one were evaluated in single studies. The Hopkins Verbal Learning Test was evaluated in three studies: the LR+ ranged from 4.8 to 49.0 and the LR- from 0.05 to 0.21. Authors' conclusions There are many instruments for the evaluation of patients with suspected cognitive impairment. No single instrument is ideal for all settings. CRD commentary This review addressed a focused question that was supported by inclusion criteria defined in terms of the intervention, participants and reference standard. The literature search was limited to two databases, included a diagnostic filter, did not attempt to locate unpublished studies, and only English language studies were included. It is therefore likely that relevant studies have been missed and the review may be subject to language and publication bias. Some steps were taken to avoid bias and error in the assessment of methodological quality, but it is not clear whether such an approach was applied to the study selection and data extraction processes. Although a quality assessment was carried out and some results of it were discussed, the results were not incorporated in the synthesis of the results.
Some study details were tabulated, but there were insufficient data on the populations studied and the reference standards used. A meta-analysis was not carried out; instead, median LRs together with ranges were presented. However, in some places in the text and in the abstract the authors stated that figures were 95% CIs when in fact they were ranges; this is potentially very misleading. The authors' conclusions are very general and relate more to implications for practice rather than relating directly to the evidence presented. Limitations of the review, especially in relation to the literature search and failure to consider study quality in the synthesis of the results, mean that the authors' conclusions and implications for practice should be interpreted with some degree of caution. Implications of the review for practice and research Practice: The authors stated that clinicians should select one primary tool based on the population, awareness of the effects of educational level, race and age on scoring, and consider adding one or two tools for special situations, if needed.
Research: The authors did not state any implications for research. Funding Durham VA Medical Center, Institute for Medical Research. Bibliographic details Holsinger T, Deveau J, Boustani M, Williams J W. Does this patient have dementia? JAMA 2007; 297(21): 2391-2404 Other publications of related interest 1. Boustani M, Peterson B, Hanson L, Harris R, Lohr KN. Screening for dementia in primary care: a summary of the evidence for the US Preventive Services Task Force. Ann Intern Med 2003;138:927-37.
2. Costa PT Jr, Albert MS, Butters NM, et al. Early identification of Alzheimer's disease and related dementias: Clinical Practice Guideline, Quick Reference for Clinicians. Rockville (MD): National Library of Medicine; 1996. Report No.: 19.
These additional published commentaries may also be of interest.
Worrall G. Review: some screening tests for dementia in older persons are accurate and practical for use in primary care. ACP J Club 2007;147:76.
Worrall G. Review: some screening tests for dementia in older people are accurate and practical for use in primary care. Evid Based Med 2007;12:182.
Kassalainen S. Review: some screening tests for dementia are accurate and practical for use in primary care. Evid Based Nurs 2008;11:23. Indexing Status Subject indexing assigned by NLM MeSH Dementia /diagnosis; Diagnosis, Differential; Humans; Memory Disorders /diagnosis; Mental Status Schedule; Neurocognitive Disorders /diagnosis; Neuropsychological Tests AccessionNumber 12007008160 Date bibliographic record published 06/12/2007 Date abstract record published 09/08/2008 Record Status This is a critical abstract of a systematic review that meets the criteria for inclusion on DARE. Each critical abstract contains a brief summary of the review methods, results and conclusions followed by a detailed critical assessment on the reliability of the review and the conclusions drawn. |
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