The age-specific quantitative effects of metabolic risk factors on cardiovascular diseases and diabetes: a pooled analysis.
BACKGROUND
The effects of systolic blood pressure (SBP), serum total cholesterol (TC), fasting plasma glucose (FPG), and body mass index (BMI) on the risk of cardiovascular diseases (CVD) have been established in epidemiological studies, but consistent estimates of effect sizes by age and sex are not available.


METHODS
We reviewed large cohort pooling projects, evaluating effects of baseline or usual exposure to metabolic risks on ischemic heart disease (IHD), hypertensive heart disease (HHD), stroke, diabetes, and, as relevant selected other CVDs, after adjusting for important confounders. We pooled all data to estimate relative risks (RRs) for each risk factor and examined effect modification by age or other factors, using random effects models.


RESULTS
Across all risk factors, an average of 123 cohorts provided data on 1.4 million individuals and 52,000 CVD events. Each metabolic risk factor was robustly related to CVD. At the baseline age of 55-64 years, the RR for 10 mmHg higher SBP was largest for HHD (2.16; 95% CI 2.09-2.24), followed by effects on both stroke subtypes (1.66; 1.39-1.98 for hemorrhagic stroke and 1.63; 1.57-1.69 for ischemic stroke). In the same age group, RRs for 1 mmol/L higher TC were 1.44 (1.29-1.61) for IHD and 1.20 (1.15-1.25) for ischemic stroke. The RRs for 5 kg/m(2) higher BMI for ages 55-64 ranged from 2.32 (2.04-2.63) for diabetes, to 1.44 (1.40-1.48) for IHD. For 1 mmol/L higher FPG, RRs in this age group were 1.18 (1.08-1.29) for IHD and 1.14 (1.01-1.29) for total stroke. For all risk factors, proportional effects declined with age, were generally consistent by sex, and differed by region in only a few age groups for certain risk factor-disease pairs.


CONCLUSIONS
Our results provide robust, comparable and precise estimates of the effects of major metabolic risk factors on CVD and diabetes by age group.
Department of Nutrition, Harvard School of Public Health, Boston, Massachusetts, USA.
Gitanjali M
GM
Singh
Goodarz
G
Danaei
Farshad
F
Farzadfar
Gretchen A
GA
Stevens
Mark
M
Woodward
David
D
Wormser
Stephen
S
Kaptoge
Gary
G
Whitlock
Qing
Q
Qiao
Sarah
S
Lewington
Emanuele
E
Di Angelantonio
Stephen
S
Vander Hoorn
Carlene M M
CM
Lawes
Mohammed K
MK
Ali
Dariush
D
Mozaffarian
Majid
M
Ezzati
D000328:Adult; D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D001786:Blood Glucose; D001794:Blood Pressure; D015992:Body Mass Index; D002318:Cardiovascular Diseases / Q000453:epidemiology* / Q000378:metabolism; D002784:Cholesterol / Q000097:blood; D003920:Diabetes Mellitus / Q000453:epidemiology* / Q000378:metabolism; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D063868:Patient Outcome Assessment; D012306:Risk; D012737:Sex Factors
D001786:Blood Glucose; D002784:Cholesterol