Characterisation of non-warfarin-associated bleeding events reported to the Norwegian spontaneous reporting system

Abstract

The aim of the study was to analyse non-warfarin-associated bleeding adverse drug events reported to the Norwegian spontaneous reporting system, with characterisation of the bleeding locations, outcome and drug interactions. In addition, concordance in assessments between reporters and evaluators, trend shifts in reporting, and detection of potentially new adverse drug interaction signals were studied. Data on bleeding events reported between 1 January 2003 and 31 December 2005 were retrieved from the Norwegian spontaneous reporting system database. Of 327 case reports of non-warfarin-associated bleeding events, 270 reports (82.6 %) were characterised as serious and 69 (21.1 %) had a fatal outcome. One hundred and eighty-seven bleeds (57.5 %) were gastrointestinal, 57 (17.4 %) were cerebral, and 81 (24.8 %) were from other bleeding sites. The bleeding sites differed with respect to the patient's age, drug use, diagnoses and outcomes. Of drugs associated with bleeding, nonsteroidal anti-inflammatory drugs (NSAIDs)/COX-2 inhibitors (145 reports) and acetylsalicylic acid (128 reports) were most frequently used. Only fibrinolytics were associated with increased mortality. There was a 67.4 % correlation between reporters and evaluators in assessment of drugs associated with bleeding (P < 0.001), with considerable variation in concordance between drug groups. Non-warfarin-associated bleeding events are associated with substantial mortality. Old age, cerebral bleeds, number of drugs used, and use of fibrinolytics are all independently associated with increased mortality. The recognition of the bleeding risk of commonly used drugs such as acetylsalicylic acid and heparins may be insufficient among prescribers.