Occurrence and relative risk of stroke in incident and prevalent contemporary rheumatoid arthritis

Objective In contrast with the wealth of data on ischaemic heart disease in rheumatoid arthritis (RA), data on stroke are scarce and contradictory. Despite the high clinical and aetiological relevance, there is no data regarding when (if ever) after RA diagnosis there is an increased risk. Our objective was to assess the risk of stroke (by subtype) in contemporary patients with RA, particularly in relation to time since RA diagnosis. Methods One incident RA cohort diagnosed between 1997 and 2009 (n=8077) and one nationwide prevalent RA cohort followed at Swedish rheumatology clinics between 2005 and 2009 ((n=39065) were assembled). Each cohort member was matched to a general population comparator. Information on first-time hospitalisations for stroke up to 2009 was retrieved from the Swedish Patient Register. HR and 95% CI were estimated using Cox models. Results In prevalent unselected RA, the HR of ischaemic stroke was 1.29 (95% CI 1.18 to 1.41). In the incident RA cohort, the overall risk increase was small and nonsignificant (overall HR 1.11, 95% CI 0.95 to 1.30). When stratified by RA disease duration, an increased risk of ischaemic stroke was indeed detectable but only after 10 or more years since RA diagnosis (HR>10 years: 2.33, 95% CI 1.25 to 4.34). Risk of haemorrhagic stroke was increased in prevalent but not in incident RA. Conclusion The magnitude of stroke risk is lower than for ischaemic heart disease in RA, and the evolvement of this risk from RA diagnosis may be slower. This suggests different driving forces behind these two RA co-morbidities and has implications for the clinical follow-up of patients with RA.