Susan Gladstone

(1) Mrs Gladstone had been prescribed warfarin for a number of years and her levels were regularly checked by the Anticoagulation Service. On 20th December 2020 Mrs Gladstone was prescribed tramadol for low back pain, with a further prescription on 4th January 2021.

(2) On 21st December 2020 her International Normalised Ratio [INR] was found to be 3.3. When she was admitted to Lister Hospital on 6th January 2021 tests showed her INR to be 11.6. Immediate action to reverse this was taken. The evidence showed that this level of blood thinning was likely to cause significant bleeding including in the brain. The cause of death was bleeding in the brain (3) A comment from the Anticoagulation Service in relation to tramadol reads "Known interactor although this is not listed in the BNF, from experience we have seen that this can increase the INR." There was nothing to warn the prescribing doctor of any possible interaction.(4) I found on the balance of probabilities that an interaction between tramadol and warfarin had caused this dangerous, and in the event fatal, INR level to develop.