Signalering van beginnende Alzheimer-dementie in de huisartspraktijk. Ontwikkeling en validering van de observatie lijst voor vroege symptomen van dementie (OLD)

Aim of the study was the development and validation of a short observation list of possible early signs of dementia (OLD) for use in general practice. A stepwise development was carried out using reviews of publications and expert consensus. Experimental observations were carried out by 22 general practitioners in 19 Dutch practices. A field study (with interviews and family forms) was conducted out afterwards, to evaluate reliability and validity. Data reduction techniques were used to construct a short version. The first two patients seen on 15 working days (N=470) were observed. Inclusion criteria: age > 75, without a known diagnosis of dementia. Exclusion: psychiatric treatment, severe depression, acute illness with confusion. The patients were divided into three groups with no, intermediate, and the most signs (total of interviewed patients n=60; family forms n=39). Cronbach's alpha and factor-analysis were used to evaluate the reliability. The Cognitive Screening Test (CST), the Word Learning Test (WLT; total and retention), the Informant Questionnaire on Cognitive Decline in the Elderly (IQCODE), the Groningen Activities Restriction Scale (GARS), and an IADL scale were used to evaluate convergent validity. The Geriatric Depression Scale (GDS) was used to evaluate discriminant validity. Construct validity was evaluated using PRINCALS. Incremental validity was evaluated using the intuitive opinion of the GP (McNemar test). The reliability in the total group was 0.88, the first factor explained 42,5% of the variance. Convergent validity (2-side ANOVA) results: CST (p=0.00), WLT-total (p=0.001), WLT retention (p=0.00), IQCODE (p=0.09). No statistically significant differences were found for GARS and IADL. The GDS (p=0.30) showed no difference. The first factor of PRINCALS explained 48% of the variance. The OLD added to the GP opinion (McNemar p=0.00). Reliability of the short version (12 items) was 0.89 (interviewed group), and 0.86 (total group). The conclusion is that the OLD is a valid and reliable method to detect early signs of dementia in general practice.