Table 2.

Questions included in the interview guide

Topic	Main questions and probes
Introduction	First of all, could you tell me a bit about yourself? Probes: • How many adult patients with aHUS do you typically treat in a year? • What are the main challenges in treating these patients? • How are treatment decisions typically made in your department?
Management of ‘straightforward’ cases	If I asked you to give me an example of a ‘straightforward’ case that you treated recently, how would this look like? Probes: • What made this case straightforward? • How long was the patient left on treatment? • How often do you have cases like this? • Is this how you typically manage such cases?
Management of ‘challenging’ cases	Looking back to your career so far, what would you say was the most ‘challenging’ case of an aHUS patient that you have treated? Probes: • What made it so challenging? • How long was the patient left on treatment? • How often do you have cases like this? • Is this how you typically manage such cases?
Treatment monitoring and management of relapse	Could you tell me a bit about the monitoring process and your approach to the management of relapse? Probes: • How often do you monitor the patient during treatment? And after discontinuing treatment? • How common is it for a patient to relapse after treatment discontinuation and what do you do in such a case? • Based on your experience, what are common risk factors influencing relapse rates? What are common relapse consequences?
Considerations guiding treatment discontinuation decisions	In general, what factors do you take into account when deciding to discontinue treatment? Probes: • If I asked you to rank all the factors that you’ve mentioned in terms of importance, would you be able to do so? • Are there any non-clinical factors that you typically consider? • Is mutational analysis readily available to you? How long does it take to get the results? How heavily do the results weigh on a treatment duration decision? • What kind of tools or types of evidence do you consider when deciding to discontinue treatment? • How do patients typically react when hearing about the discontinuation of their treatment?
Wrap-up	[Interviewer provides a brief summary of the discussion and asks for verification] Is there anything else that you feel is important to mention?