Table 3. Results regarding the acceptability and feasibility of the intervention and the evaluation design.

Central aspects	Research questions
Intervention design
Acceptability	The participants agreed that the intervention was easy to navigate and use and they found each feature useful.
	However, independently of each other, participants in both groups needed the option to elaborate on their daily responses in the Combined Symptom Medication Score (CSMS), believing it would yield more accurate data for the ILIT.NU trial. Some days, they felt that their responses were inaccurate because the influence of different factors on their responses was not considered. It concerned:
	Their behaviour and level of exposure, for example, whether they had spent much time outdoors or indoors or whether they had been travelling abroad.
	If they were unsure whether their symptoms were caused by grass pollen or other factors, such as dust mites or influenza.
	Additional symptoms caused by grass pollen that were important to them but were not included in the CSMS, such as itching of the mouth or throat.
	The number of puffs, drops and pills taken each day, as they thought it had an important impact on the severity of their symptoms.
	There were no discrepancies in the findings and agreements from the two meetings. The findings and agreements from the first were reaffirmed in the second, illustrated in the first quotation. Although not explicitly stated, the phrase ‘what the others said’ is understood to refer not only to participants in the current discussion, but also to those from the previous meeting, indicating alignment across both groups:
	“I can align myself with what the others said – it was easy to use (…). And just as the others said, I also sometimes need to be able to add some comments. I think there were some days where my symptoms, for good reasons, were non-existent (…). You know, you think that you’ve just had 3 days without symptoms – but that’s not true. I wish I could have reported that there was a reason my symptoms were extreme. That was something I missed (…). Another thing I didn't think was considered was, have you taken symptom-relieving medication? Yes, I have. How much have you actually taken? Well, there’s a big difference between just taking one pill and it goes away or having to take four.” Participant 4
	“It’s more that I feel there were some days where my symptoms, for good reason, were non-existent. Like, either it was one of those days where it was just really rainy, or I had been indoors, or I had… you know, one of those times where you think, “I've had 3 days without symptoms,” but that’s not really accurate. And I felt like there was no space to note that there were reasons why… for example, I live in the countryside. Often, that results in the pollen levels being way up… and that meant I was totally knocked out. I really wish I could have written down that there was a reason why my symptoms were extreme — that was missing. I actually called you to ask about it. I said, “I can’t really register anything correctly — well, I can log how I’m feeling — but there’s a reason for it.” I was also missing that field the others mentioned.” Participant 5
	“I found it very easy and straightforward to use. I did experience a few issues where not all parts of the system worked properly. But yes, overall it was the same – it was easy, very manageable, very simple. You quickly got used to assessing your day, like how it had been, and then it was actually quite quick to go in and go through the questions that were there. But I do think it could have gone into more detail in some places — for example, whether you had taken medication several times a day, and how many pills, because that was also something that could happen.” Participant 2
	Scoring their symptoms on a scale from 0 to 3 also posed challenges, as they found it difficult to assess what the research team meant by the different graduations. Therefore, they requested a guide to assist with this.
	Summing up, the intervention was generally well-received by both participants, researchers and clinicians, and only minor refinements were needed.
Reach	While the overall response rate on the CSMS was high in both groups, a few participants in each group had response rates below 60%. An exclusion threshold for the ILIT.NU trial. This raises uncertainty about whether the intervention reached those with the greatest need for support.
Mechanisms of change	Four out of five participants believed that using the intervention had a positive impact on their response rate; especially the ‘questionnaires to be answered’ feature, which allowed them to answer missed questionnaires up to 48 hours later. The last participant perceived themselves as very conscientious and, therefore, responded every day regardless of the intervention’s features.
Unintended effects	The intervention did not result in flawed data for the ILIT.NU trial or any other unintended effects. The entered data were correctly recorded in REDCap. When it comes to the option to only complete the entire questionnaire on days with symptoms, participants had no doubts about the questions: ‘Your use of medication in the last 24 hours—did you use symptom-relieving medication?’ and ‘Your allergy symptoms in the last 24 hours—did you have allergy symptoms?’. They argued that there was no uncertainty, especially when dealing with a chronic condition like grass pollen allergy. Additionally, they were already familiar with the questionnaire from the baseline season as they had answered it throughout the entire grass pollen season of 2021.
Participant responsiveness	The participants mainly used the ‘questionnaires to be answered’ feature, allowing them to answer missed questionnaires up to 48 hours later. They used the other features in varying ways, but they found every component useful.
Software bugs	Due to technical issues, the pollen count did not work on most days. It needed to be fixed as the participants wanted to use the feature. The remaining features functioned as intended.
Evaluation design
Efficacy signals	The initial analyses indicate notable differences between the intervention and control groups regarding the IMI scores and the response rates of the CSMS and the Rhinoconjunctivitis Quality of Life Questionnaire (RQLQ). Participants in the intervention group tended to have higher scores and response rates than those in the control group, as reflected by a greater proportion of completed daily questionnaire entries over the 100-day period.
	Response rate	Mean (min; max) (%)	Median (IQR) (%)	Intrinsic motivation	Median (IQR)
				Inventory Scale
	CSMS		p=0.587	Interest/enjoyment	p=0.008
	Intervention	84.7 (40;100)	93 (83–98)	Intervention	5.5 (4.5–5.5)
	Control	79.1 (16;100)	87 (65–96)	Control	4.0 (2.8–4.5)
	RQLQ		p=0.858	Perceived competence	p=0.047
	Intervention	76.5 (15;100)	85 (62–92)	Intervention	6.7 (6.3–7.0)
	Control	73.0 (8;100)	77 (62–92)	Control	6.0 (5.3–7.0)
				Pressure/tension	p=0.366
				Intervention	1.0 (1.0–1.0)
				Control	1.0 (1.0–1.7)
				Perceived choice	p=0.444
				Intervention	5.0 (4.3–5.7)
				Control	5.0 (4.0–5.7)
				Value/usefulness	p=0.067
				Intervention	7.0 (5.7–7.0)
				Control	5.7 (5.0–6.0)
	With an intraclass correlation of 0.2 and an effect estimate of 5.6 percentage points, the power of the future definitive trial with an expected difference in response rate of 5.6 percentage points would be 0.79, if all eligible participants consent to participate.
Recruitment	The recruitment target was met within the specified timeframe, as all 30 who were invited provided written consent and were randomised. Therefore, we considered the recruitment rate to be 100%. Both genders were represented, and the age distribution in the ILIT.NU trial was reflected.
Retention	All participants provided outcome data. However, as mentioned above, a few participants had a response rate lower than 60% on the CSMS. None were lost to follow-up during the grass pollen season, but three participants did not attend the collaborative learning meetings.
Methods for data collection	In the intervention group, nine participants (60%) completed the Intrinsic Motivation Inventory (IMI), while 11 participants (73%) in the control group completed it, which was considered acceptable. There was a tendency for a ceiling effect, especially on the pressure/tension scale items.
	Completion of the IMI was acceptable, with 60% in the intervention group and 73% in the control group. A ceiling effect was observed, particularly on the pressure/tension scale.
Randomisation	The randomisation procedure was feasible. Participants were willing to be randomised and there were no issues with using REDCap for randomisation. Researchers who were not authorised to access the randomisation key and the allocation concealment were also unable to do so.