Table 2.

Proposed daily diary items

Lunch/evening diary
Instructions (Availability to fill out: lunch diary 12–14 hours, evening diary 18–20 hours)		Lunch: Hello & welcome to your digital diary! Please reflect on last night and this morning, and rate the following statements. Self-reflections can help to understand your daily routines and needs better. Let’s get started. Evening: Welcome back to your daily diary. Please take 2–3 min to reflect on this afternoon.
	Construct	Item	Answering scale
		Last night, …
1	Sleep*	… I had problems falling asleep.	7-point numeric scale
2	Sleep*	… I had problems sleeping.	7-point numeric scale
3	Sleep*	… I woke up too early.	7-point numeric scale
		During the morning/During the afternoon…
4	Positive affect	… I felt happy, energetic, at ease or enthusiastic.	7-point numeric scale
5	Negative affect	… I felt down, irritated, depressed or hopeless.	7-point numeric scale
6	Stress	… I felt stressed.	7-point numeric scale
7	Fatigue	… I felt tired.	7-point numeric scale
8	Experiential avoidance/acceptance†	… I tried to distract myself when I felt unpleasant emotions. … I opened myself to all my feelings, the good and the bad.	7-point numeric scale
9	Lack of contact with present moment/present moment awareness†	… I did most things on ‘automatic’ with little awareness of what I was doing. … I was attentive and aware of my emotions.	7-point numeric scale
10	Self as content/self as context†	… I criticised myself for having irrational or inappropriate emotions. … I tried to see the larger picture, even when I was down, depressed or hopeless.	7-point numeric scale
11	Fusion/defusion†	… distressing thoughts tended to spin around in my mind like a broken record. … I was able to notice my thoughts and feelings without getting overwhelmed by them.	7-point numeric scale
12	Lack of contact with values/values†	… I didn’t have time to focus on things that are important to me. … I tried to connect with what is truly important to me.	7-point numeric scale
13	Inaction/committed action†	… negative feelings trapped me in inaction. … I didn’t quit working towards what is important even if it was though.	7-point numeric scale
14	Pain level	… my overall pain level was:	0 (no pain) to 10 (worst pain imaginable)
15	Pain interference	… my pain interfered with my…	7-point numeric scale General activities Mood Walking abilities Normal work (including housework) Relations with others Enjoyment of life
16	Pain catastrophising (rumination)	… I kept thinking about how much I hurt.	7-point numeric scale
17	Pain catastrophising (magnification)	… I felt my pain overwhelmed me.	7-point numeric scale
18	Pain catastrophising (Helplessness)	… I was afraid that my pain would get worse.	7-point numeric scale
19	Pain avoidance	… I avoided planning activities because of my pain.	7-point numeric scale
20	Pain self-efficacy	… I could do some form of housework/paid/unpaid work, despite the pain.	7-point numeric scale
21	Pain self-efficacy	… I could live a normal lifestyle, despite the pain.	7-point numeric scale
22	Open question	I would also like to share this about my morning/afternoon:	Free text
23	Treatment interaction‡	Today, I completed a treatment module.	Yes. No, because it was a ‘module free day’. No, but I will do it tonight. No, because: free text
	Instructions	Lunch: Thank you & have a nice afternoon! Evening: Thank you very much for taking the time to fill in your diary. Have a nice evening!

7-point numerical scale ranges from 1: not at all, to 7: very much; alternatively, based on user input, a visual analogue slider scale from 0: not at all, to 100: very much might be used.

*Sleep items only as part of the morning questionnaire.

†Both psychological flexibility and inflexibility items will be tested to determine which are more feasible and suitable to use.

‡Treatment interaction item only as part of the evening questionnaire.