Change in incidence of ischemic stroke and mortality among patients with atrial fibrillation over a period of 30 years, a nationwide, register-based cohort study

Abstract

Abstract Background During the last decades we have faced large changes in lifestyle and cardiovascular risk factor patterns, as well as screening and treatment advances of patients with atrial fibrillation (AF). Aim To investigate trends in ischemic stroke (IS) and mortality in Sweden over a period of 30 years among patients with AF and compare it to matched controls without AF. Methods This is a Swedish nationwide registry-based retrospective case-control study of patients diagnosed with AF combining data from National Patient Register (NPR) and Cause of Death Register between 1987 and 2018. Controls were defined as Swedish inhabitants without AF and matched by age, sex and county. With the use of international classification of diseases (ICD) 9- and 10- codes we identified all patients diagnosed with AF, and comorbidities at baseline from NPR. Results In total, we identified 739,388 patients with AF and 1,386,448 matched controls. The mean age of the study population was 78.8 (12.6); and (46.2%) were female. Cochran-Armitage test showed a significant increase of all comorbidities over time, except for myocardial infarction for patients and PAH för controls. The Incidence rate for IS per 1000 person-year within one year declined from 40.9 (95% C.I.: 30.1-55.6) in 1987 to 16.2 (95% C.I.: 9.9-26.4) in 2017 (p <.0001) for patients with AF and from 12.2 (95% CI: 7.0-21.4) in 1987 to 6.2 (95% CI: 2.8-13.7) in 2017 (p <.0001) in controls. The prescription of oral anticoagulant therapy (OAK) increased from 40% in 2006 to almost 80% in 2018. The total 1-year mortality rate of IS was at 175.4 (151.3-203.4) for AF cases and 58.3 (45.1-75.4) for controls (p<0001). Compared to controls and adjusted for age, sex and comorbidities patients had HR for IS at 3.01 (95% CI: 2.89-3.13) between 1987 and 1999 that decreased to HR 2.75 (95% CI: 2.63-2.88) between 2010 and 2017 in patients with AF. After adjustment for baseline comorbidities and OAK the one-year risk for IS decreased from HR 1.01 (95% CI: 0.95-1.08) in 2012 to 0.41 (95% CI: 0.36-0.47) in patients and HR 0.50 (95% CI: 0.43-0.58) in 2012 to 0.37 (95% CI: 0.31-0.43) in controls, respectively (both p<0.0001). Conclusions This study revealed significant prognostic improvement of patients with AF showing decrease in the incidence rate and relative risk for IS, as well as all-cause mortality within one year of AF diagnose. The prescription of OACs almost doubled between 2006 and 2018 in patients with AF and was associated with a significant decrease of the relative risk for IS to almost same level as in controls without AF.