Abstract: We retrieved 24,310 citations after removal of duplicates. We reviewed the full text of 317 full-text articles and finally included 70 records, referring to 48 studies, in our synthesis. We were able to perform meta-analysis on 28 studies in the community setting (44 articles) and on 6 studies in primary care (8 articles), but we could not extract usable 2 x 2 data for the remaining 14 community studies, which we did not include in the meta-analysis. All of the studies in the community were in asymptomatic people, whereas two of the six studies in primary care were conducted in people who had symptoms of possible dementia. We judged two studies to be at high risk of bias in the patient selection domain, three studies to be at high risk of bias in the index test domain and nine studies to be at high risk of bias regarding flow and timing. We assessed most studies as being applicable to the review question though we had concerns about selection of participants in six studies and target condition in one study. The accuracy of the MMSE for diagnosing dementia was reported at 18 cut points in the community (MMSE score 10, 14-30 inclusive) and 10 cut points in primary care (MMSE score 17-26 inclusive). The total number of participants in studies included in the meta-analyses ranged from 37 to 2727, median 314 (interquartile range (IQR) 160 to 647). In the community, the pooled accuracy at a cut point of 24 (15 studies) was sensitivity 0.85 (95% confidence interval (CI) 0.74 to 0.92), specificity 0.90 (95% CI 0.82 to 0.95); at a cut point of 25 (10 studies), sensitivity 0.87 (95% CI 0.78 to 0.93), specificity 0.82 (95% CI 0.65 to 0.92); and in seven studies that adjusted accuracy estimates for level of education, sensitivity 0.97 (95% CI 0.83 to 1.00), specificity 0.70 (95% CI 0.50 to 0.85). There was insufficient data to evaluate the accuracy of the MMSE for diagnosing dementia subtypes.We could not estimate summary diagnostic accuracy in primary care due to insufficient data. The MMSE contributes to a diagnosis of dementia in low prevalence settings, but should not be used in isolation to confirm or exclude disease. We recommend that future work evaluates the diagnostic accuracy of tests in the context of the diagnostic pathway experienced by the patient and that investigators report how undergoing the MMSE changes patient-relevant outcomes.

Plain-language summary: Two of the studies had serious design weaknesses with regard to their methods for selecting participants, three with regard to the application of the test (MMSE), and nine with regard to the presentation of flow and timing. We were able to do a combined statistical analysis (meta-analysis) on 28 studies in the community setting (44 articles) and 6 studies in primary care (8 articles), but we could not extract usable data for the remaining 14 community studies. Two of the six studies in primary care were conducted in people who had symptoms of possible dementia. We were able to calculate the summary diagnostic accuracy of the MMSE at three cut points in community-based studies, but we didn't have enough data to do this in the primary care studies. A perfect test would have sensitivity (ability to identify anyone with dementia) of 1.0 (100%) and specificity (ability to identify people without dementia) of 1.0 (100%). For the MMSE, the summary accuracy at a cut point of 25 (10 studies) was sensitivity 0.87 and specificity 0.82. In seven studies that adjusted accuracy estimates for level of education, we found that the test had a sensitivity of 0.97 and specificity of 0.70. The summary accuracy at a cut point of 24 (15 studies) was sensitivity 0.85 and specificity 0.90. Based on these results, we would expect 85% of people with dementia to be correctly identified with the MMSE, while 15% would be wrongly classified as not having dementia; 90% of those tested would be correctly identified as not having dementia whilst 10% would be false positives and might be referred for further testing. Our results support the use of the MMSE as part of the process for deciding whether or not someone has dementia, but the results of the test should be interpreted in broader context of the individual patient, such as their personality, behaviour and how they are managing at home and in daily life.