Table 6.

Illustrative verbatim quotes from semi‐structured interviews performed with general practitioners to identify contributing factors to oral anticoagulant‐related adverse drug reactions

Category	Illustrative verbatim quote
The patient	Intentional non‐adherence ‘I sometimes have people on oral anticoagulants who experience hematuria. So you have people on two doses a day who only want to take one. With all the consequences … It seems that for 12 hours they are anticoagulated, and for 12 hours they are not.’ [GP4] Unintentional non‐adherence ‘To come back to that patient who had been on Sintrom [acenocoumarol] and then moved on to DOAC, I didn't think of checking regularly with him whether he understood the usefulness of his drugs and whether he followed his treatment correctly. It took an acute episode to make me realize that the patient was no longer able to manage his medications.’ [GP7] Complex condition ‘With elderly people who don't drink very much, take diuretics, take an ACE inhibitor, and then have a fever and don't drink for three days, we are called after three days. When we monitor renal function, we get some serious surprises.’ [GP1]
The health care professional	Drug knowledge ‘I have some fears, because I don't have enough knowledge. There is a huge amount you need to learn about these anticoagulants. … So with those, I manage less, I manage less. Because I don't know enough about those products.’ [GP17] ‘And I had a serious problem two weeks ago. I was on duty on a Friday night. I was called at 12:30–1:00 am by a nursing home because an elderly person had fallen. So I asked the caregiver, “Are there any anticoagulants?” That's the first thing I ask. “Ah, I don't think so, I don't know.”’ [GP20] Knowledge of the patient ‘There was a patient who came to my office one day because he came to live near here and he said, “Well, I have to take Marcoumar [phenprocoumon] because I have had two pulmonary embolisms. I was told that was a lifelong treatment.” But I don't have much information about him.’ [GP3]
The task	Drug selection ‘My brain has absorbed one [new molecule] and I use that one because I know it and know how to use it. I'm not going to start mixing the others.’ [GP11] Drug–drug interactions ‘But [interactions] happen. [The patient] comes back from a specialized consultation where she received an antibiotic, and Sintrom [acenocoumarol] was not considered.’ [GP18] ‘But there are some anti‐inflammatory drugs that are, well, clearly not recommended, and yet I'm very unsure what to do. So sometimes I pretend to forget … an ibuprofen simply disappears.’ [GP21] Patient monitoring ‘It's very instinctive [dose adjustment]. It's rather unscientific and very instinctive. But I think it's kind of instinctive for everyone. Do we decrease by 1? Do we increase by 1? Do we halve? Do we make 3/4?’ [GP11] ‘There is no follow‐up [with DOACs]. We check for kidney function and things like that, but there is no particular follow‐up. Well, there is less follow‐up, anyway.’ [GP15] Perioperative management ‘[The patient] had to have a knee prosthesis. So, he was switched to fraxiparin, and when he was discharged from hospital, they let him out with a prophylactic dose of fraxiparin, not a therapeutic dose. He had a minor stroke, fortunately minimal, but he did have a minor stroke.’ [GP3]
Communication	Primary–secondary care communication ‘When I have to contact a cardiologist in a hospital setting, sometimes I spend three quarters of an hour with the phone and music; sometimes I have one or two consultations while trying to get through on the phone, so it's very unpleasant for me.’ [GP17] ‘A patient whose treatment is changed without warning the general practitioner, I don't find that … especially because we have a particular treatment in mind and it is actually no longer the same.’ [GP15] ‘Because we also see, for example, people who are discharged from hospital with a discharge letter [for the general practitioner] about medication, dosage, and all that. And they are also given a document with patient instructions about the treatment. And in that document, it's not the same.’ [GP9] GP–patient communication ‘And then I see someone come in who doesn't even suspect that she had a haemoglobin level of 7, and who came because she needed Xarelto [rivaroxaban], which I had refused to prescribe on the phone.’ [GP18]
The work environment	Workload ‘As I told you, it takes discipline, that's all. But for that, you need time. Because people with lots of patients don't have the time to follow the [INR] rates of all their patients and that could be a problem.’ [GP3] Consultation costs ‘I had a patient who lost his BIM status [increased reimbursement for health care]. He used to come every month for INR monitoring, as regular as clockwork. He lost his status and I've only seen him twice this year. Not even twice: I saw him once … Why? Because now he has to pay for his consultation. He will be reimbursed afterwards, OK. But …’ [GP11] Lack of specific consultation ‘When they come for something else, and then in the list of prescriptions there is this drug [the anticoagulant] in addition, I'm not involved in the same way as when they come specifically for their anticoagulation.’ [GP1] Banalization of anticoagulation ‘With DOACs, the idea was sold to us that they were reliable and there wouldn't be any problem with them, to the extent that if you are not kind of cautious and vigilant as a doctor, there's a danger you won't carry out those blood tests every three months.’ [GP4]