Analgesic use before and after oral anticoagulant initiation--a population-based study in Finland

Due to potential drug-drug interactions and subsequent bleeding risk, analgesic use should be reviewed when an oral anticoagulant is initiated. The aim of this study was to compare use of non-steroidal anti-inflammatory drugs (NSAIDs) and other analgesics before and after oral anticoagulant initiation.

All individuals who initiated warfarin, dabigatran, or rivaroxaban between January 2012 and September 2013 were identified from the Finnish Prescription Register. Prevalence of analgesic use during 3 months after oral anticoagulant initiation was compared to analgesic use during 4 months before initiation. Analgesics included were NSAIDs, paracetamol, paracetamol in doses ≥ 2 g/day, tramadol, and other opioids. Conditional logistic regression was used to calculate odds ratios (OR) with 95% confidence intervals (CI).

In total, 54,025 initiated warfarin, 16,894 rivaroxaban, and 1569 dabigatran. The odds of NSAID use decreased among warfarin initiators (odds ratio (OR) 0.10; 95% confidence interval (CI) 0.09-0.10); 2.6% used NSAID after initiation. In contrast, the odds of NSAID use increased among rivaroxaban (OR 3.56; 95% CI 3.37-3.75) and dabigatran initiators (OR 1.44; 95% CI 1.16-1.78). The proportions using NSAIDs after the initiation were 69 and 32%, respectively. However, NSAID use decreased among dabigatran initiators with confirmed atrial fibrillation (OR 0.46; 95% CI 0.23-0.92) and among rivaroxaban initiators with a daily dose of ≥ 15 mg (OR 0.28; 95% CI 0.19-0.40).

The use of NSAIDs decreases extensively among warfarin initiators which is encouraging. However, the use of NSAIDs increases among rivaroxaban and dabigatran initiators. This is a concern as the bleeding risk may increase due to potential pharmacodynamic interactions.