A panel of experts reviews appropriate use of assays and testing in patients with hemophilia to guide treatment in the setting of multidisciplinary management.
Peter L. Salgo, MD: If you want to dose emicizumab, what laboratory tests are you looking for?
Robert F. Sidonio Jr, MD: That’s a challenge these days. One of the typical test that we use in the United States is the 1-stage factor VIII assay. That’s a clot-based assay. That test cannot be used. And that’s another thing we have to teach our colleagues. If somebody is on emicizumab and I check factor VIII activity level, it could be 300%. It’s not 300%, but you’re getting that false reassurance. And then, their PTT [partial thromboplastin time] will be normal up to 3 to 6 months after they stop taking the drug. It’s the same issues that we have with the DOACs [direct oral anticoagulants], some of the issues about using the assays.
The chromogenic assay with bovine components can be used. The challenge is that most institutions in the United States do not have the chromogenic assay. But now, at least, I can [persuade] my pathology colleagues to say, “Hey, we need to get this.” We’ve gotten it recently. There are other resources like the CDC [Centers for Disease Control and Prevention], where you can still send it in to measure the inhibitor. We’ve had to adjust the assays that we have. They’re available, but as you know, you have to get them onboard in your hospital.
Peter L. Salgo, MD: But is it important to get them at all?
Robert F. Sidonio Jr, MD: Yes, I personally think you should have that. For example, if you are taking care of primarily older patients, what we’re seeing is for some of those surgeries that they had delayed—they had that bad elbow—they didn’t have good therapy before. Now they have something that is adequate for hemostasis, and we’re having people come in saying, “I want to get my elbow done, now that we have some better therapies.” We like to monitor that if it’s possible. We still want to be able to monitor things. We’re all doctors. We want to be able to check a lab that might help us.
Peter L. Salgo, MD: I’ll do a little role-playing here. Your phone rings. “Hello, I’m Joe or Jean’s surgeon. Don’t confuse me with details. What do I do? I want to fix the knee, I want to fix an elbow, what do I need to measure? What do I need to know before going in? What do I need to know once I’m there?”
Tim Boonstra, RPh: Well, you might not have to measure anything.
Peter L. Salgo, MD: He said I did. He promised me that I need an assay.
Tim Boonstra, RPh: I think with experience, as the hematologist and the surgical group get used to working with patients who might be on emicizumab, they could have the factor VII available. That’s the product that our group has used judiciously. But they found they haven’t had to use as much factor VII as they thought they might.
Peter L. Salgo, MD: Let me see if I hear what you’re telling me. Someone who is on emicizumab and doing well—maybe no bleeding, maybe only a very little bleeding—comes to you for elective surgery. You’re not going to order one of the chromo-whatever thingamajigs? You’re just going to say, “I’m a surgeon, I’m going to surge”?
Robert F. Sidonio Jr, MD: There are 2 populations, right? In an inhibitor population, we really haven’t been able to measure anything. We’re fine going that way, it hasn’t changed. But in the non-inhibitor patients, we’re very used to following and tracking levels. In younger children, there’s a little bit more leeway. But as you get older, you don’t want to have those really high peaks of factor VIII because then they have to go see a cardiologist. We’ve had patients have MIs [myocardial infarctions] or strokes, so we have to be very careful we don’t overdose. Again, it’s a good problem to have where we can back up our current therapies, but obviously we want to care for patients appropriately.
Peter L. Salgo, MD: This is tricky stuffy. But it seems to me to emphasize hemophilia treatment centers [HTCs].
Robert F. Sidonio Jr, MD: Yes.
Peter L. Salgo, MD: A surgeon who works routinely with a treatment center is going to be more experienced. Do you have a cadre of surgeons with you?
Lacey Chapman, RPh: No, I work in a mail order pharmacy and we’re not associated with an HTC.
Peter L. Salgo, MD: You’re not. What about you?
Tim Boonstra, RPh: Yes. Our hematology group has colleagues in all the various kinds of specialties.
Robert F. Sidonio Jr, MD: Even surgeons, they’re friends too.
Tim Boonstra, RPh: Exactly.
Peter L. Salgo, MD: Really?
Tim Boonstra, RPh: Yes. I don’t know about anesthesiologists.
Peter L. Salgo, MD: We’re the outside, lonely guys. We don’t make friends, we sit in the back and do the crossword puzzle. It’s OK.
Tim Boonstra, RPh: But there’s definitely a consult. When we get alerted to a possible surgery, it’s our group that goes ahead and puts in a treatment plan for that surgery, makes sure that the hospital pharmacy has the right product available, and knows if they’re going to get a bolus before their surgery or that they have it available and ready for a continuous infusion until the patient is discharged. All that work is done ahead of time.
Robert F. Sidonio Jr, MD: They’ve got to make sure we have factor available, so we have to keep an eye on them. They need to know we have enough in stock.
Peter L. Salgo, MD: It could be, “Hello, Blood Bank, can I get some factor?” “Oh, we don’t have that.” That would be a bad thing.
Robert F. Sidonio Jr, MD: We joked about the anesthesiologists, but they’re actually our ally, and they’re the ones catching things because they’re doing that intake. They’re calling up and saying, “Hey, this man has Von Willebrand disease and he’s about to have surgery tomorrow.” They often capture things and are our ally with regard to management, because they are actually actively involved.
Peter L. Salgo, MD: I’ll tell you, the fear of the anesthesiologist is that you’re going to get into the middle of a surgery and not have something you need.
Robert F. Sidonio Jr, MD: Exactly.
Peter L. Salgo, MD: Whether it’s factor VII or whatever else it is.
Robert F. Sidonio Jr, MD: You guys are good planners.
Peter L. Salgo, MD: We are, we tend to be. Thank you.