Does coffee trigger atrial fibrillation — or have doctors been warning people away from caffeine without strong evidence? We dig into two recent randomized clinical trials testing whether caffeinated coffee causes dangerous heart rhythm problems. Along the way, we talk about AFib, survival analysis, intention-to-treat versus as-treated analyses, and one surprisingly elaborate effort to catch clinical trial cheaters with receipts and geolocation tracking. We also explore how a pope may have fueled a European coffee resurgence, why plants make caffeine, and how a game show competition explains hazard ratios.Statistical topicsadherence and complianceas-treated analysisconfidence intervalsCox proportional hazards regressionhazard ratiosintention-to-treat analysismicro-randomizationmultiple testingPICOTpre-registrationprimary vs secondary outcomesrandomized clinical trialssensitivity analysesSMART frameworksurvival analysisMethodological morals“Never trust conventional wisdom until you see the randomized controlled trial.”“Trust your participants, but design the study so that they can be honest about their dishonesty.”ReferencesHarrington D, D'Agostino RB Sr, Gatsonis C, et al. New Guidelines for Statistical Reporting in the Journal. N Engl J Med. 2019;381(3):285-286. doi:10.1056/NEJMe1906559Marcus GM, Rosenthal DG, Nah G, et al. Acute Effects of Coffee Consumption on Health among Ambulatory Adults. N Engl J Med. 2023;388(12):1092-1100. doi:10.1056/NEJMoa2204737Wong CX, Cheung CC, Montenegro G, et al. Caffeinated Coffee Consumption or Abstinence to Reduce Atrial Fibrillation: The DECAF Randomized Clinical Trial. JAMA. 2026;335(4):317-325. doi:10.1001/jama.2025.21056@MarcKatzMD’s short video The Pitt- atrial fibrillation cardioversion scene Kristin and Regina’s online courses: Demystifying Data: A Modern Approach to Statistical Understanding  Clinical Trials: Design, Strategy, and Analysis Medical Statistics Certificate Program  Writing in the Sciences Epidemiology and Clinical Research Graduate Certificate Program Programs that we teach in:Epidemiology and Clinical Research Graduate Certificate Program Find us on:Kristin -  LinkedIn & Twitter/XRegina - LinkedIn & ReginaNuzzo.com(00:00) - - Introduction (02:15) - - What is AFib? (04:36) - - Frisky Goats and Satan's Bitter Invention (10:44) - - How Caffeine Works (14:43) - - The CRAVE Trial (15:53) - - PICOT: Evaluating the Study Design (24:21) - - CRAVE Results (31:04) - - Catching the Coffee Cheaters (37:58) - - The DECAF Trial (42:49) - - Time-to-Event Outcomes (44:40) - - Hazard Ratios: Balance Beams Over Shark Tanks (48:25) - - DECAF Results: Team Coffee Wins (51:57) - - Why Would Coffee Be Protective? (55:16) - - Rating the Claim