The diagnostic value of recommendations taken from the NHG Standaard Dementie

Objectives: To explore and quantify the relative contribution of guideline recommendations and other determinants in the GP's diagnostic workup of patients suspected of dementia. Study design: We prospectively studied 64 GPs in a district in the east of the Netherlands who diagnosed dementia according to the national Dutch guidelines for primary care. Their diagnoses were compared to the reference standard drawn up by the memory clinic team of the Nijmegen University Medical Centre. Population: The physicians evaluated 107 patients older than 55 years suspected of dementia. Outcome measures: The predictive value of various clinical and demographic parameters in both univariate and multivariate logistic regression analyses. Results: The positive and negative predictive value of the GPs diagnosis were 0.8 and 0.7 respectively. Activities of daily living (ADL), dependency (odds ratio (OR)=5.3, p=0.03), years since symptoms first presented (OR= 1.84, p=0.03) and the presence of somatic comorbidity (OR=0.48, p=0.02) independently contributed to the prediction of presence or absence of dementia. The area below the receiver-operating characteristic (ROC) curve for these 3 variables together was 0.79. An accurate diagnosis was further associated with a home visit (OR=4.0, p=0.03) and the availability of an informant (OR=3.3, p=0,045). The number of recommendations applied did not additionally contribute to the assessment of the final diagnosis. Conclusions: The accuracy of the diagnosis made by the GPs was reasonable. For GPs, ADL dependency is a better predictor of dementia than cognitive impairment. Family physicians should be aware of diagnostic difficulties in patients with somatic comorbidity. Paying a home visit and contacting an informant arefactors contributing to better diagnosis. We were unable to confirm the diagnostic value of many of the recommendations made in the dementia guidelines.