Stroke risk doubled among patients with idiopathic inflammatory myopathies
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Although rare, patients with idiopathic inflammatory myopathies are at an increased risk for both ischemic and hemorrhagic stroke, according to findings published in Arthritis Care & Research.
“A few cohort studies have investigated the risk of stroke in [polymyositis] and [dermatomyositis] patients, all presenting an increased risk,” John Svensson, PhD, of Karolinska University Hospital, Stockholm, and colleagues wrote. “A recent meta-analysis, including three of these studies, reported a pooled relative risk for ischemic stroke in [idiopathic inflammatory myopathies (IIM)] patients of 1.61 compared to non-IIM populations but due to the heterogeneity of included studies the actual risk of stroke following IIM diagnosis is still uncertain.”
Svensson and colleagues added, “Also, few of the so far published studies have studied the risk of the two main subtypes of stroke separately and the development of stroke risk over time with start of follow-up at IIM diagnosis.”
To analyze the occurrence of ischemic and hemorrhagic stroke among patients with IIM compared with the general population, and to determine variances based on sex, age, sub-diagnoses and time since initial diagnosis, the researchers conducted a population-based cohort study using data from the Swedish National Patient Register. The register includes all nonprimary outpatient visits from 2001, and all hospitalizations from 1987, for all residents of Sweden. Members of the general population were randomly selected from the Total Population Register.
The researchers included 663 patients with newly diagnosed IIM and 6,673 individuals from the general population in their study. Each member of the study population was followed prospectively until either death, emigration, first incident of stroke or December 2013. Svensson and colleagues then estimated and compared incidence rates, rate differences and hazard ratios for members of both groups, stratified by age, sex, variety of IIM and time since diagnosis.
According to the researchers, there were 34 strokes recorded among patients with IIM, and 663 among the members of the general population. In addition, increased risks for both ischemic (HR = 2.1; 95% CI, 1.4-3) and hemorrhagic (HR = 1.9; 95% CI, 0.7-5.5) stroke were seen among patients with IIM, even as few hemorrhagic-stroke events were reported. This association remained elevated after adjusting for the competing risk for death. For ischemic stroke, the rate difference was highest among patients aged 68 years or older. Hemorrhagic stroke was highest in the patients aged less than 56 years.
“Our findings indicate that individuals with IIM have an increased risk of both hemorrhagic stroke and ischemic stroke,” Svensson and colleagues wrote. “It should be kept in mind that even if the risk is elevated, stroke is still a rare event. Therefore, focus on prevention should be made in groups with the highest absolute risk.” – by Jason Laday
Disclosure: Svensson reports no relevant financial disclosures. Please see the study for all other authors’ relevant financial disclosures.