Prevalence of Abdominal Aortic Calcification in Ankylosing Spondylitis Cohort
Salim Sebaoui (1), Gillian Fitzgerald (2), Finbar O' Shea (2)
1. School of Medicine, Trinity College Dublin; 2. Department of Rheumatology, St James's Hospital, Dublin 8
Ankylosing spondylitis (AS) is a chronic inflammatory condition predominantly affecting the axial skeleton. Recent literature has demonstrated an increased cardiovascular (CV) risk in AS patients. Abdominal aortic calcification (AAC) on plain radiographs is a marker of CV risk, both in the general population and in rheumatoid arthritis (RA), with an estimated prevalence of 25 to 50% in people over 50 years. To our knowledge, no studies have reported on AAC in AS.
The aim of this study is to determine the prevalence of AAC in AS and explore relationships.
AS patients were recruited from the St. James’s Hospital Spondylitis Clinic. Demographic data, comorbidities, patient-reported outcome measures and spinal metrology were collected. Lateral lumbar spinal radiographs were evaluated by consensus using a previously validated 24-point AAC severity scale (AAC24), where 0 represents no AAC and 24 represents maximum AAC. AAC24 scores were subdivided into four categories (0: no calcification, 1-4: mild, 5-12: moderate, and >12 severe). Radiographic severity was quantified using the modified Stoke AS spinal score (mSASSS). Statistical analysis was performed using SPSS software.
Between May and July 2017, 57 patients with radiographic AS (mean age: 50.89 (± 11.36) years; 73.7% (n=42) male) were consecutively recruited. Baseline demographic and disease-related variables are outlined in Table 1. Aortic calcification is present in 36.8% (n=21) of the cohort; 22.8% (n=13) are mild and 14% (n=8) are moderate. AAC24 correlates positively with age (r=0.415, p<0.01; mean age difference 6.6 years, p=0.03), disease duration (r=0.412, p<0.01) and delay to diagnosis (r=0.3, p=0.02). The prevalence of hypertension is significantly higher in patients with calcification than those without (52.4% (n=11) vs. 22.2% (n=8), p=0.04). In smokers, AAC24 correlates positively with increasing number of cigarettes per day (r=0.334, p=0.04). There is no difference in the prevalence of AAC in patients with hypercholesterolaemia or diabetes. There is no association between AAC24 and mSASSS, BASDAI, ASDAS or BASMI. However, there is a positive correlation with both AS quality of life (ASQoL) (r=0.33, p=0.01) and fatigue severity scale scores (r=0.272, p=0.04).
The prevalence of AAC in this AS cohort is 36.8%, which is comparable to that of the general population and RA. Age and hypertension are associated with AAC. Of specific interest, there is no relationship with disease activity or radiographic damage, but patients with AAC have worse quality of life scores. Further studies are required to explore the association of AAC with CV disease in AS patients.