Clinical judgment of GPs for the diagnosis of dementia: a diagnostic test accuracy study.

Background: GPs often report using clinical judgment to diagnose dementia.

Aim: To investigate the accuracy of GPs' clinical judgment for the diagnosis of dementia.

Design & Setting: Diagnostic test accuracy study, recruiting from 21 practices around Bristol, UK.

Method: The clinical judgment of the treating GP (index test) was based on the information immediately available at their initial consultation with a person aged ≥70 years who had cognitive symptoms. The reference standard was an assessment by a specialist clinician, based on a standardised clinical examination and made according to the 10th revision of the International Classification of Diseases (ICD-10) criteria for dementia.

Results: A total of 240 people were recruited, with a median age of 80 years (interquartile range [IQR] 75-84 years), of whom 126 (53%) were men and 132 (55%) had dementia. The median duration of symptoms was 24 months (IQR 12-36 months) and the median Addenbrooke's Cognitive Examination III (ACE-III) score was 75 (IQR 65-87). GP clinical judgment had sensitivity 56% (95% confidence interval [CI] = 47% to 65%) and specificity 89% (95% CI = 81% to 94%). Positive likelihood ratio was higher in people aged 70-79 years (6.5, 95% CI = 2.9 to 15) compared with people aged ≥80 years (3.6, 95% CI = 1.7 to 7.6), and in women (10.4, 95% CI = 3.4 to 31.7) compared with men (3.2, 95% CI = 1.7 to 6.2), whereas the negative likelihood ratio was similar in all groups.

Conclusion: A GP clinical judgment of dementia is specific, but confirmatory testing is needed to exclude dementia in symptomatic people whom GPs judge as not having dementia.