Background The risk of ischemic stroke (IS) is increased in patients with rheumatoid arthritis (RA), at least in patients with longstanding disease. Little is known about the clinical phenotype, case-fatality and influence of traditional risk factors on the IS risk in RA.
Objectives To investigate whether the i) clinical presentation, ii) case-fatality and iii) impact of traditional risk factors differs in patients with prevalent RA and incident IS compared to general population comparators with incident IS.
Methods A cohort of 39065 individuals with prevalent RA between 2005 and 2009 was identified using the Swedish nationwide patient registry. The RA-cohort and 171965 general population comparators, matched on sex, birth year and residential area, were followed through 31st Dec 2009 to identify all individuals with an incident IS.
Linkage with the patient-registry and cause of death registry provided information on preexisting comorbidities and identified all deaths after the IS-event until end of follow-up 31st Dec 2011. Information on clinical characteristics, treatment and length of hospitalization was retrieved from the national quality of care registry for stoke, Riks-Stroke. Case-fatality rates were compared using the Kaplan-Meier method and Cox regression models. Cox models with age as the time scale and risk factors as time dependent covariates was used to determine their impact on the IS.
Results 640 individuals in the RA-cohort and 2040 comparators developed an IS during the follow-up. Clinical information was available for 538 RA-cases and 1805 population-cases. There was no difference in stroke severity (level of consciousness at admission), or the proportions of cases who received treatment with thrombolysis. Length of hospitalizations and the proportion of cases who required any follow-up care was also similar between the two cohorts. Overall survival was similar the first month following the IS. 25% of RA-cases compared to 19% of population-cases died within the first year after IS (HR 1.3 [95% CI 1.1-1.5]). During the entire follow-up period (mean 2.8 yrs), 46% (Incidence rate [IR] 18.4/100 person-years) of RA-cases vs. 33% (IR 11.5/100 person-years of population-cases died (HR 1.5 [95% CI 1.3-1.7]), which was similar to the relative mortality-differences between the underlying RA and population cohorts in the absence of IS. Analyses of risk factors for IS (table) indicated that the impact of atrial fibrillation on the risk of developing IS was similar between RA- and population-cases, whereas the influence of other risk factors was significantly lower among RA-cases.
Conclusions The increased risk of IS in prevalent RA cannot entirely be explained by traditional risk factors, which suggests that additional mechanisms drives the risk increase in RA. There is no difference in neither the clinical presentation of IS nor the case-fatality after IS between RA patients and general population.
Disclosure of Interest None declared
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