Background Carotid artery intimal medial thickness (IMT) on ultrasound (US) is a validated measure of subclinical cardiovascular (CV) disease. Rates of IMT progression of 0.001cm/year1 have been observed in the general population and faster progression is associated with increased CV risk.
Objectives To describe change in IMT over 5 years in a cohort of early inflammatory arthritis (IA) patients and the association of IMT with estimated CV risk and IA related factors.
Methods Between 2004 and 2010, patients enrolling in the Norfolk Arthritis Register (a UK inception cohort of IA patients) aged from 16 to 65 years with symptom duration less than 2 years, were invited to take part in the NOAR CVD sub-study. In addition to standard IA disease assessments at 0, 2 and 5 years, traditional CV risk factors were measured at baseline and Framingham based 10-year CV risk score was calculated. IMT was measured in the common carotid arteries at baseline and year 5 using a previously validated US protocol. Patient reported clinical CV events at follow up visits which were then verified by a physician. The associations of baseline CV risk and IA characteristics (tender and swollen joint count, rheumatoid factor, CRP, health assessment questionnaire (HAQ), baseline disease modifying anti-rheumatic therapy use) with baseline IMT (IMT0) and change in IMT at year 5 (IMTΔ) were tested using non-parametric statistics. The association of IMTΔ with IA characteristics over time (cumulative joint counts, change in HAQ) and medication use during follow up (statins, biologic therapy) with IMTΔ were explored using non-parametric statistics.
Results 201 patients with a median (IQR) age and symptom duration of 51 (42, 58) years and 10.4 (7.7, 14.4) months respectively were studied. 143 (71%) subjects were female. Median IMT0 was 0.06 (0.05, 0.07) cm and median IMTΔ at 5-year follow up period was 0.01 (0, 0.01) cm with an estimated median annual IMTΔ of 0.002cm. IMT had progressed in 104 (51.5%) patients and regressed in 23 (11.4%) patients by year 5. The median CV risk score at baseline was 5.6 (2.6, 10.7)% and was associated with IMT0 but not IMTΔ (r=0.46,p<0.01; r=0.03, p=0.73 respectively). There was no association between baseline IA characteristics and IMT0 or IMTΔ. There was a trend towards an association between cumulative swollen joint count and IMTΔ (r=0.14, p=0.057) but no association with cumulative tender joint count, change in HAQ, statin or biologic use (all p>0.05). CV events occurred in 5 patients during follow up. Of these patients, 3 had IMT progression, 1 had no change and 1 had IMT regression.
Conclusions Overall, patients with early IA had a higher than expected rate of IMT progression; a significant proportion however had regression in IMT over time. Trajectories of CV risk may vary within the IA population and identifying protective factors will help to better target strategies for CVD prevention in IA.
G Howard et al. Carotid artery intimal-medial thickness distribution in general populations as evaluated by B-mode ultrasound. ARIC Investigators. Stroke. 1993;24:1297–1304.
Disclosure of Interest None declared