Regular use of acetaminophen or acetaminophen-codeine combinations and prescription of rescue therapy with non-steroidal anti-inflammatory drugs: a population-based study in primary care

Objective: There are contrasting positions concerning the benefit-risk ratio of acetaminophen use for osteoarthritis (OA)-related pain. To clarify the effectiveness of acetaminophen or acetaminophen-codeine combinations according to their regimen of use, we evaluated whether being a regular user (adherent) of these medications decreased the occurrence of rescue therapy with non-steroidal anti-inflammatory drugs (NSAIDs). Methods: Using the Health Search IMS Health Longitudinal Patient Database, we formed a cohort of patients aged >= 18 years and newly treated with acetaminophen or acetaminophen-codeine combinations for OA between 1 January 2001 and 31 December 2013. These patients were followed up for one year in which they were categorized as regular or irregular users of these medications according to a variable medication possession ratio (VMPR) >= 50% or lower. We operationally defined the rescue therapy as the use of any NSAIDs prescribed for OA-related pain. Results: Overall, 40,029 patients (69.5% females; mean age: 68 +/- 13.57) treated with acetaminophen or acetaminophen-codeine combinations formed the cohort. After the first year of treatment, regular users showed a statistically significantly lower risk of being prescribed with rescue therapy with NSAIDs (OR = 0.89; 95% CI 0.84-0.96). Conclusion: These findings show that regular use of acetaminophen or acetaminophen-codeine combinations may reduce the need for NSAIDs to treat OA-related pain.