How did the authors arrive at their bad news? They analyzed 32,602 Danes who were diagnosed with atrial fibrillation or atrial flutter and compared them to 325,918 age- and sex-matched controls. Of this cohort, 2,925 cases and 21,871 controls were users of NSAIDs.
Regardless of whether non-selective NSAIDs or the relatively newer cyclo-oxygenase (COX) 2 inhibitors were used, the authors reported a 40-70% increase in the relative risk of atrial fibrillation or atrial flutter. While this may sound alarming, this is, in fact, equivalent to an extra 4 cases of atrial fibrillation each year for every 1,000 new users of non-selective NSAIDs and 7 extra cases per year for every 1,000 new users of COX 2 inhibitors.