Cross-sectional analysis of baseline data to identify the major determinants of carotid intima-media thickness in a European population: the IMPROVE study.
OBJECTIVE
The 'IMPROVE study' was designed to investigate whether cross-sectional carotid artery intima-media thickness (IMT) and overall IMT progression are predictors of new vascular events in European individuals at high risk of cardiovascular diseases. This paper reports the results of the baseline analyses aimed at identifying the major determinants of increased carotid IMT (C-IMT).


RESULTS
IMPROVE is a prospective, multicentre, longitudinal, observational study. A total of 3711 subjects (age range 54-79 years) with at least three vascular risk factors (VRFs) were recruited in seven centres in Finland, France, Italy, the Netherlands, and Sweden. Collected variables included clinical, biochemical, genetic, socioeconomic, psychological, nutritional, and educational data, personal and family history of diseases, drug intake, and physical activity. By multiple linear regression analysis, C-IMT was positively associated with latitude, age, gender, pulse pressure, pack-years, and hypertension, and inversely with educational level (all P < 0.0001 for IMT(mean-max)). Latitude was the strongest independent determinant of C-IMT (partial r(2) for IMT(mean-max) = 0.109, P < 0.0001) and alone accounted for nearly half of the variation explained by the regression model (partial r(2) for IMT(mean-max) = 0.243, P < 0.0001). The geographical gradient for C-IMT paralleled the well-known north-to-south cardiovascular mortality gradient (r(2) for IMT(mean) = 0.96).


CONCLUSIONS
Latitude is an important determinant of C-IMT, which is not explained by between-country differences in established VRFs. Other unknown contributory mechanisms such as heritable, nutritional, or environmental factors may be important in the genesis of this geographical gradient.
Baldassarre
Damiano
D
Department of Pharmacological Sciences, University of Milan, Italy.
Nyyssönen
Kristiina
K
Rauramaa
Rainer
R
de Faire
Ulf
U
Hamsten
Anders
A
Smit
Andries J
AJ
Mannarino
Elmo
E
Humphries
Steve E
SE
Giral
Philippe
P
Grossi
Enzo
E
Veglia
Fabrizio
F
Paoletti
Rodolfo
R
Tremoli
Elena
E
D000368:Aged; D002340:Carotid Artery Diseases / Q000208:ethnology / Q000473:pathology*; D017536:Carotid Artery, Common / Q000473:pathology*; D003430:Cross-Sectional Studies; D005060:Europe / Q000208:ethnology; D005260:Female; D006801:Humans; D008137:Longitudinal Studies; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D012111:Residence Characteristics; D018570:Risk Assessment; D012307:Risk Factors; D017539:Tunica Intima / Q000473:pathology; D017540:Tunica Media / Q000473:pathology; D044465:White People / Q000208:ethnology*