Abstract
IntroductionPsoriasis and psoriatic arthritis (PsA) increase cardiovascular disease (CVD) risk, but surrogate markers for CVD in these disorders are inadequate. Because the presence of sacroiliitis may portend more severe PsA, we hypothesized that sacroiliitis defined by computed tomography (CT) would be associated with increased vascular inflammation defined by 18-fluorodeoxyglucose-positron emission tomography/computed tomography (FDG-PET/CT), which is an established measure of CVD.MethodsParticipants (n = 65) underwent whole-body FDG-PET/CT. Metabolic activity of the aorta was measured using the maximal standardized uptake value (SUVmax), a measure of atherosclerotic plaque activity. The primary outcome was aortic vascular inflammation. Linear regression (with β-coefficients (β) and P-values reported for PsA and sacroiliitis) was used to adjust for CVD risk factors to determine associations of PsA or sacroiliitis with vascular inflammation. Likelihood ratio testing was performed to evaluate the contribution of sacroiliitis to vascular disease estimation compared to the effects of PsA and traditional CVD risk factors.ResultsVascular inflammation (measured as SUVmax) was greater (P < 0.001) in patients with sacroiliitis (mean ± SD = 7.33 ± 2.09) defined by CT compared to those without sacroiliitis (6.39 ± 1.49, P = 0.038). There were associations between PsA and aortic inflammation (β = 0.124, P < 0.001) and between sacroiliitis and aortic inflammation (β = 0.270, P < 0.001) after adjusting for CVD risk factors. Sacroiliitis predicted vascular inflammation beyond PsA and CVD risk factors (χ2 = 124.6, P < 0.001).ConclusionsSacroiliitis is associated with increased vascular inflammation detected by FDG-PET/CT, suggesting that sacroiliac joint disease may identify patients at greater risk for CVD. Large, ongoing prospective studies are required to confirm these findings.Electronic supplementary materialThe online version of this article (doi:10.1186/ar4676) contains supplementary material, which is available to authorized users.
Highlights
Psoriasis and psoriatic arthritis (PsA) increase cardiovascular disease (CVD) risk, but surrogate markers for CVD in these disorders are inadequate
Median skin disease duration was 20 years for both the Pso and PsA subgroups, and the median duration of joint disease was 10 years in PsA patients (Table 1). One patient met both the Calin and ASAS criteria for inflammatory back pain. This patient was classified as having Pso, due to not meeting the CASPAR criteria for PsA and having computed tomography (CT) images showing advanced degenerative and postsurgical changes in the spine without evidence of spondylitis or sacroiliitis
Two additional patients were definitively diagnosed with sacroiliitis by CT without evidence of inflammatory back pain, SI tenderness to palpation or provocative maneuvers, arthritis, enthesitis or dactylitis
Summary
Psoriasis and psoriatic arthritis (PsA) increase cardiovascular disease (CVD) risk, but surrogate markers for CVD in these disorders are inadequate. Systemic inflammatory disorders, including psoriasis (Pso) [1,2,3] and psoriatic arthritis (PsA) [3], increase incident cardiovascular events beyond traditional cardiovascular disease (CVD) risk factors [4]. Understanding of this elevated risk has been hampered by the lack of suitable clinical biomarkers linking systemic inflammation and CVD. We have previously demonstrated relationships between FDG-PET/CT imaging measurements and both known and novel CVD biomarkers, thereby validating FDG-PET/CT findings as reliable predictors of outcome [15] These pilot studies were underpowered to adequately assess for PsA or axial disease
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