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Reference: van Oijen, 2005
Cohort: Rotterdam Study
Risk Factor: Inflammatory Biomarkers


Average Follow-up Time Detail
At the baseline examination between 1990-1993, 7047 people were screened for dementia and had blood samples drawn. 334 prevalent cases of dementia were excluded, leaving a cohort of 6713 at risk for dementia. Follow-up examinations occurred between 1993-1994, and again in 1997-1999. In addition, linkage with records of general practitioners allowed for continuous monitoring of the cohort for morbidity and mortality, resulting in complete follow-up through January 1, 2000.

Exposure Detail
"High sensitivity C-reactive protein (HsCRP) was measured for the total cohort in baseline serum samples kept frozen at -20 degrees Celcius, using a rate near-infrared particle immunoassay method (Immage, Beckman Coulter). The range of measurement was 0.2 to 1440 mg/L with a variation coefficient of 3.1%."

Because of the skewed distribution of C-reactive protein, instead of the mean (SD), the median (interquartile range) is provided. Median CRP = 1.9 mg/L, IQR: (0.9, 3.6)

Ethnicity Detail
Study participants were residents of Ommoord, a suburb of the city of Rotterdam, the Netherlands

Age Detail
The age provided is the age at the start of follow-up of dementia.

Screening and Diagnosis Detail
Screening Method:
CAMDEXCambridge Examination for Mental Disorders of the Elderly
GMSGeriatric Mental State Schedule (Copeland 1976)
MMSEMini-Mental State Examination (Folstein 1975)

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

Total dementia definition: DSM-III-revised.

Screening: (Described in van Oijen et al. 2005) "The diagnosis of dementia was made following a 3-step protocol. Two brief tests of cognition (Mini-Mental State Examination [10] and Geriatric Mental State schedule [11] organic level) were used to screen all of the subjects. Screen-positives (Mini-Mental State Examination score 26 or Geriatric Mental State organic level 0) underwent the Cambridge examination for mental disorders of the elderly (Camdex) [12]. Subjects who were suspected of having dementia were, if necessary, examined by a neuropsychologist. In addition, the total
cohort was continuously monitored for incident dementia through computerized linkage between the study database and digitalized medical records from general practitioners and the Regional Institute for Outpatient Mental Health Care."

Covariates & Analysis Detail
Analysis Type:
Cox proportional hazards regression

HsCRP was not normally distributed, so investigators used log-transformed hsCRP in the analyses. They excluded perople with hsCRP levels > 3 times the SD of the log-transformed hsCRP, which resulted in a total of 6247 measurements.

AD Covariates:
Aage
Ggender
APOE4APOE e4 genotype
ATHatherosclerosis
BMIbody mass index
DMdiabetes mellitus
DBPdiastolic blood pressure
HDLHDL cholesterol
SMsmoking status
SHstroke history
SBPsystolic blood pressure
TCtotal cholesterol

TD Covariates:
Aage
Ggender
APOE4APOE e4 genotype
ATHatherosclerosis
BMIbody mass index
DMdiabetes mellitus
DBPdiastolic blood pressure
HDLHDL cholesterol
SMsmoking status
SHstroke history
SBPsystolic blood pressure
TCtotal cholesterol

It is not clear which covariates are included in the model for the AD results. We have included the covariates from the most-adjusted model for the total dementia results, which are found in Table 4. Other covariates considered by the study authors include fibrinogen and white blood cell count.