This study is based on three cohorts.
Tayside Screening for Cardiovascular Events (TASCFORCE) study comprised of 1,528 participants who have undergone WB-MRA.
It enrolled low to intermediate risk participants free from cardiovascular disease.
It was used to derive a carotid-femoral artery length formula.
The arterial length from the right common carotid artery bifurcation to the aortic arch and from aortic arch to bifurcation of the right common femoral artery were measured by one of 4 image analysts in Carestream PACS software (Client Suite Version 10.1 sp1,
Rochester,
NY,
USA) Fig. 1 Fig. 2. The distance travelled by pulse wave was derived as aortic arch to bifurcation of the right common femoral artery minus right common carotid artery bifurcation to the aortic arch.
PWV calculated using this formula will be referred to as PWVMRA.
Inter-observer variability was assessed to confirm inter-reader consistency.
Surrogate Markers of Micro- and Macro-vascular hard end-points for Innovative Diabetes Tools (SUMMIT) study was comprised of 1242 participants from 3 European centres (Dundee,
Exeter and Pisa).
It included healthy individuals,
participants with diabetes and cardiovascular disease.
All participants had PWV measurements with SphygmoCor device.
Their arterial length was measured with following formula: suprasternal notch to umbilicus + umbilicus to femoral artery - suprasternal notch to carotid artery.
This measurement will be referred to as PWVSUMMIT.
Caerphilly Prospective Study (CaPS) aimed to recruit all men aged 45 to 59 years old between 1979 and 1983.
825 participants had PWV at one of the follow-ups.
Their arterial length was calculated as suprasternal notch to femoral artery minus carotid to suprasternal notch distance.
Their PWV calculation will be referred to as PWVCAPS.
|
TASCFORCE
|
SUMMIT
|
CApS
|
N
|
1,183
|
929
|
825
|
Age (years)
|
54.1 ± 8.3
|
68.4 ± 8.5
|
72.3 ± 3.9
|
Sex (male)
|
433 (37%)
|
606 (65.2%)
|
825 (100%)
|
Systolic BP (mmHg)
|
122.2 ± 12.2
|
133.8 ± 17.7
|
141.4 ± 19.4
|
Diastolic BP (mmHg)
|
72.6 ± 9.2
|
74.8 ± 8.8
|
74.2 ± 11.2
|
Table 1.
Demographics of study participants
The formula for arterial length was derived from the TASCFORCE study using the linear regression modelling to quantify the following factors: sex,
age,
height,
weight,
waist circumference,
systolic blood pressure,
diastolic blood pressure,
heart rate,
cholesterol,
high density lipoprotein,
low density lipoprotein,
triglycerides,
glucose,
smoking status,
smoking years,
pack years,
and body mass index.
Backward linear regression was performed to reduce the number of factors in the final formula.
It is known that age,
gender and presence of cardiovascular disease have influence on PVW.
Two of three SUMMIT centres recruited participants under the age of 62 so comparison between these three centres only included those >62 years of age (735 participants).
CaPS study involved males ≥65 with significantly lower prevalence of cardiovascular disease in comparison with SUMMIT.
For comparison between all 4 centres including SUMMIT and CaPS only males ≥65 years of age and free from cardiovascular disease were included (918 participants).
PWV calculation was compared between the centres using ANCOVA with PWV as an independent variable,
study centre as a fixed variable and age,
gender and mean arterial pressure as covariates.
Associations with cardiovascular outcomes were analyzed using logistic regression.
Statistical analysis was performed with SPSS statistical package (version 21.0,
IBM SPSS,
Chicago,
Illinois) and RStudio (The R Foundation,
Version 3.3.2).
Significance was assumed at p<0.05.