Respiratory tract infection and risk of bleeding in anticoagulant users

Ahmed et al undertook a study to estimate the association between untreated, community acquired, respiratory tract infections and bleeding in oral anticoagulant users

• Self-controlled case series
  
  
• Setting General practices in England contributing data to the Clinical Practice Research Datalink GOLD
  
  
• Participants 1208 adult users of warfarin or direct oral anticoagulants with a general practice or hospital admission record of a bleeding event between January 2010 and December 2019, and a general practice record of a consultation for a community acquired respiratory tract infection for which immediate antibiotics were not prescribed (that is, untreated)
• In this self-controlled case series of 1208 oral anticoagulant users, a greater than twofold increase was seen in the risk of major bleeding and clinically relevant non-major bleeding in the 0-14 days after a respiratory tract infection for which no antibiotics were prescribed
  
  
  • of 1208 study participants, 58% (n=701) were male, median age at time of first bleed was 79 years (interquartile range 72-85), with a median observation period of 2.4 years (interquartile range 1.3-3.8)
  • 292 major bleeds occurred during unexposed time periods and 41 in the 0-14 days after consultation for a respiratory tract infection
  • 1003 clinically relevant non-major bleeds occurred during unexposed time periods and 81 in the 0-14 days after consultation for a respiratory tract infection
  • after adjustment for age, season, and calendar year, the relative incidence of major bleeding (incidence rate ratio 2.68, 95% confidence interval 1.83 to 3.93) and clinically relevant non-major bleeding (2.32, 1.82 to 2.94) increased in the 0-14 days after an untreated respiratory tract infection
    
    
• the direction and magnitude of the association remained relatively unchanged across several sensitivity analyses and did not appear to be modified by sex or type of oral anticoagulant
  
  
• these findings are important and timely given the increasing rates of oral anticoagulant use and the lack of knowledge and guidance on how to manage oral anticoagulant use during acute infection

Reference:

1. Ahmed H, Whitaker H, Farewell D, Hippisley-Cox J, Noble S. Respiratory tract infection and risk of bleeding in oral anticoagulant users: self-controlled case series BMJ 2021; 375 :e068037 doi:10.1136/bmj-2021-068037