Association between inhaled long-acting beta-2-agonists and the risk of acutemyocardial infarction: A methodological comparison of two databases

Background: Results from multiple observational studies on inhaled long-acting beta-2-agonists (LABA) and the risk of acute myocardial infarction (AMI) are conflicting, due to variations in methodological, clinical and health care characteristics. To some extent, the discrepancies in the design might limit the comparability of the results encountered. Objectives: To determine the risk of AMI in inhaled LABA users in two European electronic primary care databases using a common study protocol. Methods: Patients from the Dutch Mondriaan (1.4 Million) and the UK CPRD (5 Million) databases were included if they had a diagnosis of asthma and/or COPD, and were prescribed at least one inhaled LABA, a short-acting beta-2-agonist (SABA), or a short- or long-acting muscarinic antagonist (SAMA, LAMA) during the study period (2002 to 2009). LABA episodes were divided into current, recent (