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

Abstract

BackgroundGPs often report using clinical judgment to diagnose dementia.AimTo investigate the accuracy of GPs’ clinical judgment for the diagnosis of dementia.Design & settingDiagnostic test accuracy study, recruiting from 21 practices around Bristol, UK.MethodThe 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.ResultsA 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.ConclusionA 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.