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AlzRisk Paper Detail

Reference: Raffaitin, 2009
Cohort: Three-City Study
Risk Factor: Diabetes Mellitus

Average Follow-up Time Detail
Of the 7738 individuals in the incident sample with fully available metabolic syndrome data, 7087 had at least one follow-up examination in the four years following baseline, and these individuals constitute the analysis sample.

While the study duration was four years, participants' average follow-up time was not reported.

Exposure Detail
Blood test results and information gleaned on medication use from baseline interviews were used to classify patients across exposure levels. Specifically, participants were considered to be hyperglycemic if their blood test results showed fasting glucose >= 110 mg/dl (>=6.1 mmol/l), or nonfasting glucose >= 200 mg/dl (>= 11.1 mmol/l), or if they were determined to have used anti-diabetic medication.

Of the 11.5% of participants classified as hyperglycemic according to the above definition, 7.6% met criteria for diabetes diagnosis, while 3.9% had elevated blood glucose without a diabetes diagnosis.

"All pharmacological treatments taken during the month preceding the time of the interview were recorded. Medical prescriptions and, when feasible, the medications themselves were checked by the interviewer...Blood samples were collected (EDTA plasma samples stored at -80°C), and centralized measurements of fasting blood glucose, HDL cholesterol, and triglycerides were performed."

Ethnicity Detail
The vast majority (97%) of participants were French speaking and 88% were born in France.

Screening and Diagnosis Detail
Screening Method:
BVRTBenton Visual Retention Test (Benton 1974)
ISTIsaacs' Set Test (Isaacs & Kennie 1973)
MMSEMini-Mental State Examination (Folstein 1975)

AD Diagnosis:
DSM IV Diagnostic and Statistical Manual IV
NINCDS ADRDA National Institute of Neurological and Communicative Diseases and Stroke/Alzheimer's Disease and Related Disorders Association Criteria (McKhann 1984)

Total dementia definition: All cause dementia defined by DSM-IV.

"First, screening was based on a thorough neuropsychological examination by trained psychologists. This examination included a battery of cognitive tests...Data on activities of daily living, severity of cognitive disorders, and, where possible, magnetic resonance images or computed tomography scans were collected 16. Second, the participants who were suspected of having dementia on the basis of their neuropsychological performance (in particular the Mini Mental Status Examination, the Benton Visual Retention Test, and the Isaac’s Set Test administered uniformly in all three study centers at each follow-up 16) were examined by a neurologist in the three study centers 16. Finally, all suspected dementia cases were analyzed by a common independent committee of neurologists according to the criteria of the DSM-IV 16... With regard to the different subtypes of dementia, we considered the two most frequent causes of dementia as determined by committee (Alzheimer’s disease according to National Institute of Neurological and Communicative Disorders and Stroke and the Alzheimer’s Disease and Related Disorders Association criteria 16 and vascular and vascular dementia based on history of vascular disease, Hachinski score 16, and magnetic resonance imaging whenever possible).”

Covariates & Analysis Detail
Analysis Type:
Cox proportional hazards regression

"Associations between metabolic syndrome, or each of its components, with incident dementia over 4 years were estimated using separate proportional hazards models with delayed entry and age as time scale (9). This model allowed estimation of the strength of the association between metabolic syndrome and each of its components with age at onset of dementia, taking censoring by death or loss to follow-up into account, over the 4 years of follow-up."

AD Covariates:
SPstudy population

TD Covariates:
SPstudy population