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identified nationwide claims database, and reported that
age was a strong predictor of type 2 diabetes, hypercho-
lesterolaemia, hypertension, cardiac dysrhythmias, and
atherosclerosis, such that mean disease-free survival
rates were significantly less for middle-aged (40–< 60
years) and older (≥ 60 years) subjects compared with
young adults (18–< 40 years) (11). Despite the fact that
this was the first longitudinal cohort study to investi-
gate cardiometabolic disease in adults with CP, other
important risk factors, such as gross motor function
and physical activity, were unavailable for analysis and
may have influenced the disease-free survival trends.
In addition to traditional risk factors for CVD (e.g.
hypertension and increasing age), measures of arterial
structure and function (12) have emerged as novel (i.e.
non-traditional) independent risk factors for CVD.
Specifically, physiological changes, such as reductions
in elastin and increases in collagen formation, lead to
a stiffer arterial wall and a widened pulse pressure,
resulting in systolic hypertension. Measuring these
non-traditional CVD risk factors could add prognostic
value to the assessment and treatment of CVD in this
population. We previously showed the feasibility of as-
sessing non-traditional risk factors for CVD, including
arterial stiffness and endothelial dysfunction through
cross-sectional studies of adolescents (13) and adults
with CP (8). A better understanding of change over time
could assist clinicians to identify those individuals with
CP who are most at risk of CVD, and may help institute
and evaluate interventions to mitigate those risks. The
objectives of this study were to examine longitudinal
changes in both traditional and non-traditional risk fac-
tors for CVD in individuals with CP, and to investigate
the associations between age and gross motor function
with longitudinal changes in these risk factors.
METHODS
This study was a component of the Stay-FIT program of research
at CanChild, Centre for Childhood Disability Research. The
purpose of the Stay-FIT programme of research is to promote
physical activity and encourage an active lifestyle for indivi-
duals with CP across the lifespan. Adolescents and adults with
CP (n = 53), who previously participated in cross-sectional
studies (8, 13) within the Stay-FIT programme including car-
diovascular health assessments, were invited to participate in
this longitudinal study. All individuals with CP were eligible
for the present study, regardless of intellectual ability and gross
motor function. Participant or parent/caregiver written consent
was obtained prior to study commencement. This study received
local institutional review board approval (Hamilton Integrated
Research Ethics Board Project #12-110).
Participant characteristics
All participants were invited to a research laboratory within a
university setting to undergo a battery of cardiovascular health
www.medicaljournals.se/jrm
assessments. All participants arrived at the laboratory having
abstained from food, caffeine and vigorous physical activity
for at least 12 h prior to data collection. The visit began with
measures of height and body mass, as reported previously (8).
These were used to calculate body mass index (BMI; kg/m 2 ).
Waist circumference was measured to the nearest 0.5 cm at the
end of a normal expiration 4 cm above the umbilicus with the
participant in the supine position. Supine systolic, diastolic,
and mean arterial blood pressures were measured using an
automated blood pressure device (Dinamap PRO 100 series,
Tampa, FL, USA). These assessments were performed by a
clinical researcher with > 5 years’ experience collecting these
measures in individuals with CP and spinal cord injury (first
author (PM)). For the purpose of this study, waist circumference
and systolic blood pressure (SBP) were included as traditional
CVD risk factors. The Expanded and Revised version of the
Gross Motor Function Classification System (GMFCS) (14)
was used to determine level of gross motor function via self-
report by participants.
Non-traditional cardiovascular disease risk factors
Non-traditional risk factors and details pertaining to their data
collection and analysis techniques are described below. All
measures were performed with the participant in a supine posi-
tion following 10 min of supine rest. A data acquisition system
(Powerlab model ML795; ADInstruments, Colorado Springs,
CO, USA) and software program (LabChart 8; ADInstruments,
Colorado Springs, CO, USA) were used to acquire continuous
heart rate and blood pressure during data collection. Heart rate
was obtained using electrocardiography and blood pressure was
obtained using finger photoplethysmography (Finometer MIDI,
Finapres Medical Systems, Amsterdam, The Netherlands). The
measurement protocols were identical at baseline and follow-up
assessment time-points.
Carotid distensibility
Carotid distensibility was acquired as an indicator of local
carotid artery elasticity. This technique required a combination
of brightness mode ultrasound with a 12 MHz probe (Vivid
Q; GE Medical Systems, Horten, Norway) and applanation
tonometry (model SPT-3-1; Millar Instruments, Houston,
TX, USA). Simultaneous images and tonometer signals were
acquired for 10 consecutive heart cycles. Distensibility was
calculated as follows:
Distensibility (mmHg –1 )=(π(d max /2) 2 –π(d min /2) 2 )/PP*π(d min /2) 2
where d max was the mean maximum arterial lumen diameter, d min
was the mean minimum arterial lumen diameter, and PP is the
mean pulse pressure of the carotid artery (difference between
systolic and diastolic pressure) calculated from signals acquired
using the applanation tonometer. A decrease in carotid distensi-
bility is indicative of increased artery wall stiffness.
Carotid artery intima media thickness
The same brightness mode ultrasound images that were col-
lected for carotid distensibility were used to calculate carotid
artery intima media thickness (cIMT). cIMT was measured as
the distance (mm) from the lumen-intima to the media-adventitia
interface at 100 sites along the arterial wall in the end diastolic
frame for each of the 10 heart cycles and reported as a mean for
each participant. An increase in cIMT is indicative of increased
risk of CVD.