Diagnostic yield of cognitive tests applied in primary care. Consistency and validity of screening tests

Objective: To estimate the prevalence of cognitive impairment in elderly people living in the community. To assess the diagnostic yield of the main cognitive screening tests in Primary Care: the Mini Mental State Examination (MMSE), the Clock Drawing Test (CDT), the Verbal Fluency Test (VFT) and the Informant Questionnaire test (IQ). We also calculated their correlation and validity. Design: Descriptive study based on a personal interview by professionals using a standardised method to assess cognitive impairment. Participants: A total of 293 men and women, who were older than 64 years old and residing in the province of Huesca. The sample was recruited by systematic random sampling from the database of personal health care card. Main measurementsWe analysed social and demographic variables (age, educational level, marital status) and the assessment of cognitive impairment by means of MMSE, CDT, VF, IQ tests. Results: The prevalence of cognitive impairment with MMSE was 18.1% (95% Cl: 15.3-24.4%). The correlation between MMSE and the other cognitive screening tests was moderate: CDT kappa=0.40; VF kappa=0.33; IQ kappa=0.36. Using the MMSE as a gold standard and the prior diagnosis of Cl, the sensitivity of CDT was 78.3% and the specificity was 76.9%, 80%; there was 70% sensitivity and 76.7% specificity for the VF; and 71.4% for IQ respectively. The area under the VF ROC curve was significantly higher than the other tests. Conclusions: The agreement between cognitive impairment screening tests was moderate. The VF yielded better diagnostic accuracy. (C) 2009 Elsevier Espana, S.L. All rights reserved.