Screening properties of the German IQCODE with a two-year time frame in MCI and early Alzheimer's disease.
BACKGROUND
The Informant Questionnaire on Cognitive Decline in the Elderly (IQCODE) is a widely used screening tool for dementia. We aimed to determine the ability of the German version of the 16-item IQCODE with a two-year time frame to discriminate healthy mature control participants (NC) from mild cognitive impairment (MCI) and probable early Alzheimer's disease (AD) patients (all with Mini-mental State Examination (MMSE) scores >or= 24/30) and to optimize diagnostic discriminability by shortening the IQCODE.


METHODS
453 NC (49.7% women, age = 69.5 years +/- 8.2, education = 12.2 +/- 2.9), 172 MCI patients (41.9% women, age = 71.5 years +/- 8.8, education = 12.3 +/- 3.1) and 208 AD patients (59.1% women, age = 76.0 years +/- 6.4, education = 11.4 +/- 2.9) participated. Stepwise binary logistic regression analyses (LR) were used to shorten the test. Receiver operating characteristic curves (ROC) determined sensitivities, specificities, and correct classification rates (CCRs) for (a) NC vs. all patients; (b) NC vs. MCI; and (c) NC vs. AD patients.


RESULTS
The mean IQCODE was 3.00 for NC, 3.35 for MCI, and 3.73 for AD. CCRs were 85.5% (NC-patient group), 79.9% (NC-MCI), and 90.7% (NC-AD), respectively. The diagnostic discriminability of the shortened 7-item IQCODE (i.e. items 1, 2, 3, 5, 7, 10, 14) was comparable with the longer version (i.e. 7-item CCRs: NC-patient group: 85.3%; NC-MCI: 80.1%, NC-AD: 90.5%).


CONCLUSIONS
The German 16-item IQCODE with two-year time frame showed excellent screening properties for MCI and early AD patients. An abbreviated 7-item version demonstrated equally high diagnostic discriminability, thus allowing for more economical screening.
Ehrensperger
Michael M
MM
Memory Clinic, Department of Geriatrics, University Hospital Basel, Switzerland. ehrenspergerm@uhbs.ch
Berres
Manfred
M
Taylor
Kirsten I
KI
Monsch
Andreas U
AU
D000368:Aged; D000544:Alzheimer Disease / Q000175:diagnosis* / Q000453:epidemiology*; D005260:Female; D005858:Germany / Q000453:epidemiology; D006801:Humans; D008297:Male; D008403:Mass Screening / Q000379:methods*; D009483:Neuropsychological Tests