Recommendations for the post-operative management of an existing Warfarin therapy after lower limb joint arthroplasty.

BACKGROUND: Warfarin administration after lower limb joint replacements is associated with a high bleeding risk, creating the circumstances for periprosthetic joint infections, increased treatment costs and prolonged Length of Stay (L.o.S). We believe that previously warfarinized patients can be treated safely and discharged without delays, if appropriate policies are established and adhered to.

METHODS: This is a retrospective cohort study. We have collected and analyzed data from an audit cycle between 2012 and 2015 on: 1) the post-operative Warfarin reloading protocol, identifying 4 distinct patterns: usual dose, 1.5 times or double the usual dose for 2 days and overloading, 2) timing of reloading: Evening of Surgery vs post-op Day 1, 3) frequency of INR testing: daily vs intermittent, 4) time required to reach a therapeutic INR value ≥2.0, 5) rate of INR variations ≥4.0 and 6) bleeding complications, 7) and the overall L.o.S.

RESULTS: We found a significant difference in the time required to reach an INR ≥2.0 between reloading with the usual dose and all other protocols (p < 0.001) without abolishing adverse sequelae. Daily INR testing reduced bleeding complications and INR variations at a significant (p < 0.001) and non-significant level respectively, while timing of restarting showed no significant effect. We found a correlation between INR variations and bleeding complications (odds ratio: 4.65, C.I: 0.59-30.87). 41% of the cohort was discharged on the day their INR turned therapeutic with an average L.o.S of 6.5 days.

CONCLUSION: We recommend to: 1) restart Warfarin at double (or in exceptional cases 1.5 times) the patient's maintenance dose for the first two doses, 2) starting on the Evening of Surgery, 3) with daily INR monitoring after the second loading dose, 4) using point of care testing devices, 5) and dosing thereafter to be guided by an anticoagulation service or computer assistance.