To investigate the associations between cardiorespiratory fitness (CRF) and the level of cardiovascular (CV) risk factors in patients with ankylosing spondylitis (AS) and controls.
In a cross-sectional comparative study, CRF was measured with a maximal treadmill test for estimation of peak oxygen uptake. Metabolic syndrome (MS), body composition, traditional CV risk factors, and inflammatory markers were assessed. Multivariable linear regression models were used to study the associations between CRF and CV risk factors. All models were adjusted for age, sex, and smoking, and for inflammation when C-reactive protein (CRP) level or erythrocyte sedimentation rate (ESR) were not already included as dependent variables.
A total of 126 patients (mean ± SD age 47.9 ± 10.8 years) and 111 controls (mean ± SD age 52.1 ± 11.1 years) were included. There were significant inverse associations between CRF and body mass index, waist circumference, triglycerides, CRP level, and ESR (P < 0.001-0.03) for patients and controls. Also, significant associations were found between CRF and high-density lipoprotein (HDL) cholesterol (β = 0.03, P < 0.001) and blood pressure (BP; β = -0.9 for systolic and β = -0.6 for diastolic; P < 0.01) in controls, but these associations were not found in patients (β = 0, P = 0.69 for HDL cholesterol; β = -0.04, P = 0.87 for systolic pressure; and β = -0.14, P = 0.34 for diastolic pressure) (additional adjustments for medication). Higher CRF was associated with a lower risk for MS in both patients (odds ratio [OR] 0.91, P = 0.03) and controls (OR 0.89, P = 0.01).
CRF was associated with favorable levels of CV risk factors and lower risk of MS in both AS patients and controls. However, established findings of an association between CRF and BP and HDL cholesterol in healthy adults were not confirmed in AS patients.