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AlzRisk Paper Detail

Reference: Qiu, 2003b
Cohort: Kungsholmen Project
Risk Factor: Blood Pressure

Average Follow-up Time Detail
Baseline assessments occurred between 1987 and 1989. Those participants who were free of dementia at baseline were invited to participate in subsequent follow-up examinations. The initial follow-up examinations occurred in 1991-1993, and the second set of follow-up examinations occurred in 1994-1996. Medical records and death certificates were used to identify those who died between examinations.

Exposure Detail
"Arterial blood pressure (ie, systolic Korotkoff phase I and diastolic phase V) was measured twice on the same occasion on the right arm by trained nurses using a standardized random-zero mercury sphygmomanometer, with the subject in a sitting position after at least a 5-minute rest.26 Pulse pressure was defined as the difference between systolic pressure and diastolic pressure."

Ethnicity Detail
All participants were residents of the Kungsholmen parish of Stockholm, Sweden in 1987-1989.

Age Detail
Study criteria required participants to be 75+ in October 1987.

Screening and Diagnosis Detail
AD Diagnosis:

Total dementia definition: DSM-III-R criteria for "clinically definite dementia"

"We used the Diagnostic and Statistical Manual of Mental Disorders, Revised Third Edition criteria30 to define the incident dementia cases with a 3-step diagnostic procedure, as previously described.25,31,32 In brief, 2 examining physicians independently made a preliminary diagnosis, and a third opinion was sought in case of disagreement. The diagnosis of AD requires gradual onset, progressive deterioration, and lack of any other specific causes of dementia. Our criteria for AD were similar to those from the National Institute of Neurological and Communicative Disorders and Stroke–Alzheimer’s Disease and Related Disorders Association33 for probable AD. For deceased subjects, 2 physicians made dementia or AD diagnosis by reviewing the medical records and death certificates."

Covariates & Analysis Detail
Analysis Type:
Cox proportional hazards regression

"We treated the medium category [of pulse pressure] as a reference group because preliminary analyses showed a nonlinear relationship between tertile of pulse pressure and risk of dementia. Interaction was examined by including the independent variables and their cross-product term in the same model. Stratified analyses were further performed if a statistical interaction was suggested. We considered age (years), sex, education, vascular disease, baseline MMSE score, antihypertensive drug use, pulse rate, APOE genotype (indicator variable with 4 categories of ε2/ε2 or ε2/ε3, ε3/ε3, any ε4, and missing values), and systolic pressure (indicator variable with 3 categories of <140, 140 to 180, and >180 mm Hg) and diastolic pressure (indicator variable with 3 categories of <70, 70 to 90, and >90 mm Hg) as covariates in multiple analyses. ...Education was measured by total years of formal schooling and dichotomized into <8 years (elementary school and vocational training) and >8 years (high school and university).27 Pulse rate (beats per minute) was counted for 1 minute. Information on vascular disorders at baseline was derived from the computerized Stockholm Inpatient Register system, which encompassed the discharge diagnoses from all hospitals in the Stockholm area since 1969, and included heart disease (International Classification of Diseases, Eighth Revision [ICD-8] codes 410 to 414, 427, and 428), cerebrovascular disease (ICD-8 codes 430 to 438), and diabetes mellitus (ICD-8 code 250). Information on medical drug use was collected for the 2 weeks preceding the baseline survey. We inquired about use of both prescription and nonprescription drugs, and, if possible, the drug containers and prescriptions were inspected to verify this information. Medical drugs were coded and classified according to the Anatomical Therapeutic Chemical (ATC) classification system.28 Antihypertensive drugs were defined as all medicines potentially used for lowering blood pressure (ie, ATC codes C02, C03, and C07)."

AD Covariates:

TD Covariates: