Patients with atrial fibrillation and outcomes of cerebral infarction in those with treatment of warfarin versus no warfarin with references to CHA(2)DS(2)-VASc score, age and sex - A Swedish nationwide observational study with 48 433 patients

AIMS: There is controversy in the guidelines as to whether patients with atrial fibrillation and a low risk of stroke should be treated with anticoagulation, especially those with a CHA(2)DS(2)-VASc score of 1 point. METHODS: In a retrospective, nationwide cohort study, we used the Swedish National Patient Registry, the National Prescribed Drugs Registry, the Swedish Registry of Education and the Population and Housing Census Registry. 48 433 patients were identified between 1 January 2006 and 31 December 2008 with incident atrial fibrillation who were divided in age categories, sex and a CHA(2)DS(2)-VASc score of 0, 1, 2 and ≥3 and they were included in a time-varying analysis of warfarin treatment versus no treatment. The primary end-point was cerebral infarction and stroke, and patients were followed until 31 December 2009. RESULTS: Patients with 1 point from the CHA(2)DS(2)-VASc score showed the following adjusted hazard ratios (HR) with a 95% confidence interval: men 65–74 years 0.46 (0.25–0.83), men <65 years 1.11 (0.56–2.23) and women <65 years 2.13 (0.94–4.82), where HR <1 indicates protection with warfarin. In patients <65 years and 2 points, HR in men was 0.35 (0.18–0.69) and in women 1.84 (0.86–3.94) while, in women with at least 3 points, HR was 0.31 (0.16–0.59). In patients 65–74 years and 2 points, HR in men was 0.37 (0.23–0.59) and in women 0.39 (0.21–0.73). Categories including age ≥65 years or ≥3 points showed a statistically significant protection from warfarin. CONCLUSIONS: Our results support that treatment with anticoagulation may be considered in all patients with an incident atrial fibrillation diagnosis and an age of 65 years and older, i.e. also when the CHA(2)DS(2)-VASc score is 1.