Journal Club Summary

Methodology: 4/5
Usefulness: 4/5

Kent AP, et al. J Am Coll Cardiol. 2018 Jul 17;72(3):255-267

Question and Methods: This was a post hoc analysis of the RE-LY trial examining the risk of NSAID use in patients receiving oral anticoagulation (OAC) for atrial fibrillation.

Findings: NSAID use was associated with an increased risk of major bleeding (HR 1.68), stroke or systemic embolism (HR 1.63) and hospitalization (HR. 1.64).

Limitations: This was a non-ED study, which did not examine OACs for other indications. The specifics of dose and duration of NSAID therapy were unknown.

Interpretation: Emergency physicians should exercise caution when prescribing NSAIDs to patients on OACs, and strongly consider alternative pain management options.

By: Dr. Peter Reardon

Epi Lesson

Time-Dependent Variables

Survival analyses model the time it takes before an event (outcome of interest) occurs. This time until event occurrence can be influenced and adjusted for one or more covariates. These covariates are either “static” i.e. they stay the same for the entire time period (for e.g. eye colour, or other covariate measured only once), or can be “time-dependent” and vary during the observation period until event/outcome occurrence (for e.g. taking a medication vs. not)…this implies the value is measured more than once.
By: Dr. Christian Vaillancourt


  • Dr. Rosenberg is an emergency physician at the Ottawa Hospital, assistant professor at the University of Ottawa, and Director of the Digital Scholarship and Knowledge Dissemination Program.