title: Detecting cognitive impairment in primary care: performance assessment of three screening instruments.
abstract: Early detection of Alzheimer's disease and related disorders (ADRD) is important, especially in primary care settings. We compared performances of two common screening tests, the Mini-Mental State Exam (MMSE) and Clock Drawing Test (CDT), with that of the MCI Screen ({MCIS}) in 254 patients over 65. None had previous diagnosis of ADRD, and 81% were asymptomatic by Functional Assessment Staging Test ({FAST}) (FAST=1). 215 patients completed all screening tests - 141 had >or= 1 abnormal result, 121/141 completed standardized diagnostic assessment, and the remaining 74/215 (34%) screened entirely normally and weren't further evaluated. Potential bias due to unevaluated cases was statistically adjusted. Among diagnosed cases: AD=43%, cerebrovascular disease=36%, other causes=21%. Bias-adjusted MCI prevalence for FAST stages 1 and 1-3 were 13.9-20.3% and 23.0-28.3%. Bias-adjusted results for the CDT, MMSE and MCIS were: clinical diagnosis validity (kappa statistic)={-0.02 (p=0.61), 0.06 (p=0.23), 0.92 (p< 0.0001)}; sensitivity={59%, 71%, 94%}; specificity={39%, 36%, 97%}; overall accuracy={54%, 62%, 96%}; positive predictive value={16%, 17%, 86%}; and negative predictive value={83%, 87%, 96%}. The MMSE and CDT were not valid for early detection, while the MCIS had high validity and accuracy in the primary care cohort.
authors.affiliation: Maine Coast Memorial Hospital, Ellsworth, ME 04605, USA. dtrenkle@mainehospital.org
authors.forename: Douglas L
authors.initials: DL
authors.lastname: Trenkle
authors.forename: William R
authors.initials: WR
authors.lastname: Shankle
authors.forename: Stanley P
authors.initials: SP
authors.lastname: Azen
mesh_terms: D000368:Aged; D000544:Alzheimer Disease / Q000453:epidemiology*; D003072:Cognition Disorders / Q000175:diagnosis* / Q000453:epidemiology*; D042241:Early Diagnosis; D005260:Female; D006801:Humans; D008297:Male; D008403:Mass Screening / Q000379:methods*; D009483:Neuropsychological Tests; D015588:Observer Variation; D015995:Prevalence; D011320:Primary Health Care / Q000706:statistics & numerical data*; D015203:Reproducibility of Results; D012720:Severity of Illness Index