Thank you for all of your comments this week! This week we took a walk through acquired factor VIII inhibitors.
Acquired haemophilia A is a rare disorder with an incidence of around 1.5 per 1 million per year. There can be acquired inhibitors to other clotting factors however these are less common.
The development of acquired haemophilia A can be associated with various disorders including SLE, PMR, other autoimmune disorders and it can also be associated with pregnancy and, as in our case malignancy. In around 50% of patients no underlying cause is found.
There is a mortality associated with acquired haemophilia A and this can be as a result of bleeding or infections due to the immunosuppressive effects of treatment. Because this is a rare and complex disorder, and patient with acquired haemophilia should be managed with a haemophilia centre that has experience in dealing with patients with inhibitors.
Aquired coagulation disorders should be suspected in any patient with new or abnormal bleeding. It is important to remember if people are on anticoagulation or anti platelets and they have abnormal bleeding this also warrants further investigation. There are some patients who may not present with bleeding and merely come to light by way of an abnormal clotting test.
When you are investigating abnormal clotting results, you need to know if the patient is on anticoagulation. In acquired haemophilia you should get a prolong clotting result that doesn’t correct with normal plasma. If you have an abnormal clotting result that doesn’t correct with normal plasma then factor assays should be checked. An inhibitor to the factor can then be checked using a Bethesda assay. It is also important to check for a lupus anticoagulant.
An inhibitor can also interfere with assays for other factors, if this occurs, serial dilutions can be performed to check.
When treating patients with acquired haemophilia A it is important to prevent iatrogenic bleeding. Venepuncture and cannulation should be kept to a minimum and should not be performed by inexperienced staff as these can result in significant bleeds. Nursing staff also need to be aware to keep blood pressure monitoring and bm monitoring to a minimum. Patients may be at risk of falls and staff need to be aware of this and measures put in place to prevent this.
Invasive procedures can also cause significant life threatening bleeds so consideration needs to be given as to whether these can be delayed. In our case the colonoscopy was delayed as this may have resulted in a significant bleed even with FEIBA or novo 7 cover.
Up to 30% of patients with acquired haemophilia may not need haemostatic support. Initiation of haemostatic support and care of patients needs to be under the guidance of an experienced haematology team. FEIBA, novo7 and aPCC have all been used as treatment. Desmopressin has also been used in some patients with a low level inhibitor. Tranexamic acid may also be considered in addition to other treatments.
Thrombosis may also occur during treatment with novo7 and FEIBA. Clinicians should be aware of this and investigate appropriately. Once patients are in remission with a normal factor level, thought needs to be given to appropriate thromboprophylaxis.
First line treatment for eradication of inhibitors is often steroids alone, or steroids and cyclophosphamide. Rituximab is often used as a second line treatment if there has been no response at 3-5 weeks, it can also been considered as first line if there is a contraindication to usual treatments. Ciclosporin/tacrolimus can also be considered second line.
Once the inhibitor has been eradicated patients will need to be followed up as they can relapse.
We hope you have enjoyed this case, are there any questions you have? Is there anything you would have done differently? Let us know your thoughts!