Bridging therapy increases bleeding risk

By Bianca Nogrady 
The use of bridging therapy for patients during an interruption to warfarin therapy for invasive procedures is associated with an increased risk of bleeding, a study has found.

The retrospective US cohort study in 1178 patients undergoing 1812 procedures showed a 17-­fold greater incidence of clinically relevant bleeding within 30 days in the patients who received bridging therapy during their procedure once their INR had fallen to less than 1.5 after warfarin was interrupted.

There was no significant difference in the rates of venous thromboembolism (VTE) between patients who received bridging therapy and those who did not; however, nearly 80% of the patients were classified as low risk for VTE, having not had an event for more than a year and having no other risk factors. Two­-thirds of patients classified as high­-risk for VTE received bridging therapy compared with fewer than one­ third of patients classified as low risk, according to the report published in the journal JAMA Internal Medicine.

‘Bleeding was either directly attributed to the administration of the bridging agent or a complication of the procedure in most cases,’ the authors wrote.

‘Conversely, recurrent VTE events were rare in both the bridge and nonbridge therapy groups, including within the nonbridge therapy high­-risk subgroup.’

Commenting on the study, haematologist Dr Ashley Ng said the retrospective, observational nature of the study made it difficult to determine why most of the patients who were at low­-risk of VTE were still on warfarin 12 months after their first thrombosis, or the reasons for placing them on bridging therapy before their procedure.

Dr Ng told Medicine Today that the decision whether to use bridging therapy for patients on warfarin still needs to take into account the patient’s history, in terms of their risk of VTE, and the risk level of the procedure, as per current guidelines.

‘This study supports previous evidence that low­-risk patients undergoing low­-risk procedures are at low risk of procedure­-related clots, and that bridging therapy can be associated with a higher rate of bleeding,’ said Dr Ng, from Royal Melbourne Hospital.

The low rates of VTE in the high­-risk group also suggest that bridging therapy is effective, albeit with a cost,’ he added.

Dr Ng said some procedures are known to have a higher risk of clotting, such as hip and knee surgery and surgery for cancer.

‘Each patient still needs to be assessed in context, as there is evidence that even patients with no past history of VTE are at risk of developing clots in those circumstances.’

JAMA Intern Med 2015, doi: 10.1001/jamainternmed.2015.1843.