C XU 1, A ABEYARATNE 1,3, S WONG 1, S MAJONI 1,2,3
1Royal Darwin Hospital, Darwin, Australia, 2Flinders Medical School, Flinders University, Darwin, Australia, 3Menzies School of Health Research, Royal Darwin Hospital Campus, Darwin, Australia
Warfarin for the prevention of non-valvular atrial fibrillation (AF) related thromboembolic stroke in patients on maintenance haemodialysis is a controversial issue. Despite the deliberate exclusion of haemodialysis patients in randomised control trials, the American Heart Association/American College of Cardiology (AHA/ACA) has recommended anticoagulation in high-risk AF patients. We retrospectively examined the risk and benefit of warfarin anticoagulation therapy in our prevalent haemodialysis patients over 10 years of follow-up. Eligible patients were retrospectively identified and stratified to two groups based on whether they were prescribed warfarin. The outcomes of interest were ischaemic stroke, haemorrhagic stroke and death from any cause. Rate ratio was used to compare the unadjusted rate strokes between the groups. Cox proportional hazard regression model were used to adjust for confounders. The Kaplan-Meier method and the log-rank tests were used to analyse survival. Three ischaemic strokes and four haemorrhagic strokes occurred in the unexposed group of 166 patients over 484.44 patient-years follow-up. One ischaemic stroke and no cases of haemorrhagic stroke occurred in the exposed warfarin group of 16 patients over 39.32 patient-years of follow-up. 87% of patients in both groups were indigenous. More than 90% of each cohort was had CHA2DS2VaSc score ≥2. 101 deaths occurred in the follow-up period, ninety in the unexposed group and eleven in the warfarin group. A non-statistically significant trend towards increasing mortality was observed in the warfarin group (Hazard ratio =1.63, p=0.13). This retrospective study of prevalent haemodialysis patients with co-existing history of non-valvular AF failed to demonstrate sufficient evidence for the routine use of warfarin for prophylaxis of thromboembolic stroke.
Chris is a renal trainee who recently completed 1st year training at the Royal Darwin Hospital.