Management of over-anticoagulation in warfarinised hospital patients

Aim: To determine the number of warfarinised hospital patients experiencing over-anticoagulation; to identify how overanticoagulation is managed and whether local guidelines are adhered to. Method: 2 prospective one-week clinical audits were conducted in 2005 (Audit 1) and 2008 (Audit 2). The medical notes, drug charts and anticoagulation charts of warfarinised patients admitted to hospital were reviewed. The following data were collected: medical histories, warfarin regimen, international non-nalised ratio results, clinical events and over-anticoagulation clinical management and treatment options. Results: Data were collected for 58 patients (Audit 1: n = 30; Audit 2: n = 28). At least one-third of all patients experienced over-anticoagulation (Audit 1: 53%; Audit 2: 36%). Haemorrhagic events occurred in 40% of patients in Audit 1 and 18% in Audit 2 (p = 0.06) - not all were associated with elevated international normalised ratios. Most cases of overanticoagulation were managed by withholding warfarin doses and one case (Audit 2) required Prothrombinex. Drug interactions were the most common risk factor (> 50% of patients) for over-anticoagulation in both audits. Problems with documentation were more prevalent in Audit 1 than in Audit 2. Conclusion: Over-anticoagulation is a common occurrence in warfarinised hospital patients. Hospital over-anticoagulation management practices need to be reviewed to ensure safe and efficacious anticoagulation