Background/Purpose We have previously shown that patients with ankylosing spondylitis (AS) have lower cardio-respiratory fitness (CRF) than population controls. CRF is inversely associated to risk of cardiovascular disease (CVD) in the general population. Arterial stiffness is a marker of CVD risk, and AS patients have increased arterial stiffness compared to controls. The objective was to assess associations between CRF and arterial stiffness in AS patients.

Methods

This is a cross-sectional study on AS patients (mNY criteria) where information on demographics and medication was assessed from questionnaires. Arterial stiffness (Pulse Wave Velocity (PWV) and Augmentation Index (AIx)) was recorded using the Sphygmocor apparatus (AtCor). CRF was assessed as peak oxygen uptake (VO₂peak) by a maximal walking treadmill test (modified Balke protocol). Statistics were performed using SPSS version 21. Univariate associations between lnPWV/AIx (dependent variable) and VO₂peak as well as possible confounders and factors with effect on the outcome were analyzed in separate linear regression models adjusted for age and gender. Variables with p-value<0.25 were included in backwards multivariate linear regression models.

Results

The 113 AS patients had the following characteristics: Mean (SD) age 48.4 (11.3) years, 72 (64 %) males, 18 (16%) smokers, mean (SD) BMI (kg/m²) 25.6 (3.5), median (IQR) CRP (mg/l) 3 (2-10), 73 (65%) used NSAIDs, 24 (21%) used TNF-inhibitors, 14 (12%) used statins and 28 (25%) used antihypertensive medication. In regression models VO₂peak was significantly inversely associated with lnPWV independent of other factors (table). Similar results were found for AIx (table).

 

	Outcome: lnPWV		Outcome: AIx
	Univariate Beta (95%CI)	Multivariate Beta (95%CI)	Univariate Beta (95%CI)	Multivariate Beta (95%CI)
Age	0.012 (0.009, 0.014)*	0.009 (0.006, 0.012)*	0.74 (0.60, 0.88)*	0.48 (0.32, 0.64)*
Gender (male)	0.03 (-0.04, 0.11)	0.11 (0.04, 0.17)*	-11.48 (-15.82, -7.13)*	-9.44 (-12.61, -6.24)*
VO2peak (mg/kg/min)	-0.003 (-0.007, 0.002)	-0.005 (-0.010, -0.001)*	-0.38 (-0.62, -0.15)*	-0.33 (-0.55, -0.10)*
Current smoking	-0.07 (-0.15, 0.01)		2.29 (-1.82, 6.41)
BMI	0.01 (-0.012, 0.014)		0.20 (-0.24, 0.64)
NSAIDs	-0.03 (-0.09, 0.03)		0.20 (-3.03, 3.42)
TNFα-inhibitors	0.01 (-0.06, 0.08)		0.97 (-2.84, 4.78)
Statins	-0.01 (-0.09, 0.08)		3.27 (-1.12, 7.66)
Antihypertensives	0.00 (-0.07, 0.07)		-0.10 (-3.95, 3.75)
CRP (mg/l)	0.003 (0.000, 0.005)*		0.09 (-0.05, 0.24)
Loss of height (cm)	-0.008 (-0.016, -0.001)*	-0.011 (-0.020, -0.002)*
Height (cm)			-0.16 (-0.43, 0.03)
Central mean arterial pressure (mmHg)	0.006 (0.004, 0.008)*	0.005 (0.002, 0.007)*	0.24 (0.11, 0.37)*	0.27 (0.14, 0.40)*

*p-value<0.05

Conclusion CRF measured by VO₂peak was inversely associated with arterial stiffness indicating that reduced CRF can be related to increased risk for CVD in AS patients. Studies on the effect of increasing CRF on risk of CVD in AS patients are warranted.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/low-cardio-respiratory-fitness-is-associated-with-increased-arterial-stiffness-in-patients-with-ankylosing-spondylitis/