Consistency of clinical diagnosis of dementia in NEDICES: A population-based longitudinal study in Spain.
BACKGROUND
Few longitudinal studies have verified the clinical diagnosis of dementia based on clinical examinations. We evaluated the consistency of the clinical diagnosis of dementia over a period of 3 years of follow-up in a population-based, cohort study of older people in central Spain.


METHODS
Individuals (N = 5278) were evaluated at baseline (1994-1995) and at follow-up (1997-1998). The evaluation included a screening questionnaire for dementia and a neurological assessment.


RESULTS
Dementia screening consisted of a 37-item version of the Mini-Mental State Examination (MMSE) and the Pfeffer Functional Activities Questionnaire (FAQ). Study neurologists investigated those participants who screened positively (N = 713) as well as 843 who had screened negatively to test the sensitivity of the screening instruments or because they had a positive screening for other chronic neurological diseases. We detected 295 patients among those who screened positive and 13 among those who screened negatively. Three years follow-up evaluation demonstrated 14 diagnostic errors at baseline (4.5%) leading to a final number of 306 patients with dementia. The corrected prevalence of dementia was 5.8% (95% confidence interval [CI] 5.2-6.5).


CONCLUSIONS
The diagnosis of dementia was highly accurate in this population-based, Spanish cohort study, and our prevalence figures agree with other European surveys. Given the high cost and difficulties of population rescreening and its relatively low yield, we conclude that a single 2-phase investigation (screening followed by clinical examination) provides accurate information for most population-based prevalence studies of dementia.
Department of Neurology, University Hospital "12 de Octubre," Madrid, Spain.
F
F
Bermejo-Pareja
J
J
Benito-León
S
S
Vega
J
J
Olazarán
M
M
de Toledo
J
J
Díaz-Guzmán
F
F
Sánchez-Sánchez
J M
JM
Morales-González
R
R
Trincado
A
A
Portera-Sánchez
G C
GC
Román
D000368:Aged; D000369:Aged, 80 and over; D003430:Cross-Sectional Studies; D003704:Dementia / Q000175:diagnosis* / Q000453:epidemiology*; D003951:Diagnostic Errors; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008137:Longitudinal Studies; D008297:Male; D009460:Neurologic Examination; D009483:Neuropsychological Tests; D015995:Prevalence; D012680:Sensitivity and Specificity; D013030:Spain / Q000453:epidemiology; D011795:Surveys and Questionnaires; D013997:Time Factors