Patients with atrial fibrillation and a history of gout had a higher risk of ischemic stroke than patients without gout, according to a nationwide cohort study. Among patients with both conditions, urate-lowering therapy was associated with lower stroke rates, although the observational study was not designed to determine whether treatment directly reduced stroke risk.
Researchers analyzed data from the Finnish Anticoagulation in Atrial Fibrillation (FinACAF) registry, identifying 229,565 patients with new-onset atrial fibrillation (AF) diagnosed between 2007 and 2018. Among them, 6,910 had a history of gout. During a mean follow-up of 4 years, 16,296 patients experienced an ischemic stroke.
After adjustment for demographic and clinical factors, patients with gout had a 12% higher rate of ischemic stroke than those without gout. During periods when patients were not receiving oral anticoagulation, gout was associated with a 26% higher stroke rate, consistent with the primary analysis.
The association varied by how gout was identified. Patients whose gout diagnosis was documented during hospital care had higher stroke rates than patients without gout, whereas the association was smaller and not statistically significant among patients whose gout was documented only in primary care. Researchers reported no interaction between gout and stroke-risk category, suggesting a similar relative association between gout and stroke risk across risk strata.
Among patients with gout and AF, time-dependent exposure to allopurinol or febuxostat was associated with a 30% lower stroke rate compared with periods without urate-lowering therapy. After adjustment for other risk factors, stroke rates among patients receiving urate-lowering therapy were comparable to those observed in patients without gout.
The investigators further evaluated stroke rates according to CHA₂DS₂-VA score among patients not receiving anticoagulation. Among patients who were not receiving anticoagulation, crude ischemic stroke rates in those with gout were 1.5, 1.0, and 4.8 per 100 patient-years for CHA₂DS₂-VA scores of 0, 1, and 2 or greater, respectively. The researchers noted that most patients with gout were already classified as high risk for stroke based on conventional risk assessment tools because of their substantial burden of cardiovascular and metabolic comorbidities.
Compared with patients without gout, those with gout more frequently had hypertension, diabetes, heart failure, vascular disease, renal insufficiency, prior bleeding, and prior stroke. They also had higher mean stroke-risk scores and bleeding-risk scores at baseline.
The researchers noted that the retrospective registry design could identify associations but could not establish causality. Data were unavailable for several potentially relevant variables, including serum urate levels, smoking status, estimated glomerular filtration rate, blood pressure, lipid levels, glycemic measures, and detailed measures of gout severity. Medication exposure was determined from pharmacy claims data rather than confirmed use, and residual confounding from unmeasured factors could not be excluded.
“Considering gout in addition to conventional risk scores could improve stroke risk stratification,” wrote lead study researcher Antti Palomäki, MD, PhD, of Turku University Hospital and the University of Turku, Finland, and colleagues. They noted that the findings support guideline-recommended urate-lowering therapy for gout and suggest gout may be a potentially modifiable stroke risk factor in patients with AF.
Disclaimers: The study was supported by the Aarne Koskelo Foundation, the Finnish Foundation for Cardiovascular Research, and the Helsinki and Uusimaa Hospital District research fund. Several researchers reported financial relationships with pharmaceutical and health care companies. Other researchers reported no conflicts of interest.
