A systematic review of the quality of studies on dementia prevalence in Italy

Table 3 Standardized scoring system for the assessment of quality of epidemiological trials in dementia [5]

Item	Score
Sample size
<500	0.5 points
500–1499	1 point
1500–2999	1.5 points
≥3000	2 points
Design
Two-phase study with no sampling of screen negatives^a	0 points
Two-phase study with sampling of screen negatives but no weighting back	1 point
One-phase study or two-phase study with appropriate sampling and weighting	2 points
Response proportion
<60 %	1 point
60–79 %	2 points
≥80 %	3 points
Diagnostic assessment
Inclusion of multidomain cognitive test battery, formal disability assessment, informant interview and clinical interview	1 point each

^aIn the two-phase study, all participants are evaluated in the first phase using a screening tool. All the patients with a score below a predefined cutpoint (screen positives) will enter into the second phase of the study for a more comprehensive evaluation. In order to get a more correct evaluation, a random sample with a score above the cutpoint (screen negatives) should also be included in the second phase of the study. In this way the false positive rate can be estimated among the screen negatives and the related weight (‘weight back’) can be evaluated, calculating an overall prevalence taking into account the different sampling proportions of screen positives and screen negatives. In the one-phase study, all patients directly receive a comprehensive clinical evaluation

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