Predicting The Right Advice at The Right Time in Patients With Hip and Knee OsteoArthritis: the e-cOAch Cross-over.

Measured using the Hip disability and Osteoarthritis Outcome Score (HOOS) or Knee injury and Osteoarthritis Outcome Score (KOOS). HOOS includes 40 items and KOOS 42 items in five subdomains of physical functioning. Each item is rated on a 5-point Likert scale. The total scores range from 0 to 100; a higher score represents better physical functioning.

Numeric Pain Rating Scale is a simple scale where participants rate their pain over the past week from 0 (no pain) to 10 (worst pain imaginable). This scale is widely used to track changes in pain intensity over time.

The Patient-Reported Outcomes Measurement Information Sys-tem Experience, Short-Form (SF) version 8a. Consists of eight items, each rated on a 5-point Likert scale. Higher scores indicate a lower ability to participate in social roles and activities.

Measured using the Hip disability and Osteoarthritis Outcome Score (HOOS) or Knee injury and Osteoarthritis Outcome Score (KOOS). The subscale stiffness consists of two items with a 5-point Likert scale. A higher score represents less stiffness. The HOOS and KOOS also evaluate physical functioning.

The Brief Physical Activity Assessment Tool (or in Dutch: Vragenlijst Fysieke Activiteit (VFA)) consists of two items regarding the frequency and duration of Physical activity. The subject can be classified as insufficiently (0-3 score) or sufficiently active (>3 score). Insufficient refers to not meeting the World Health Organization guideline of 150 minutes of moderate-to-vigorous physical activity per week.

In a random subset (n = 200) of the study population, physical activity will be objectively measured using an activity tracker (Fitbit Inspire 3) worn in participants' home environments for the duration of the study. Device-measured active minutes (Active zone minutes) will be used to assess if someone is meeting the World Health Organization guideline of 150 minutes of moderate-to-vigorous physical activity per week.

A numeric rating scale (NRS-11). One item reports fatigue on a scale from 0 (no fatigue) to 10 (extreme fatigue).

A Numeric Rating Scale (NRS-11). One item reports job satisfaction on a scale from 0 (not satisfied at all) to 10 (completely satisfied).

The Hospital Anxiety and Depression Scale. Fourteen items report anxiety and depression symptoms over the past month on a 4-point Likert scale. A higher score indicates more severe symptoms.

A numeric rating scale (NRS-11). One item reports experienced social support on a scale from 0 (no support) to 10 (extensive support).

The Brief Fear Of Moving has six items that report fear on a 5-point Likert Scale from 1 (strongly disagree) to 5 (strongly agree). A higher score indicates greater fear.

A shortened version of the Arthritis Self-Efficacy Scale (ASES), excluding the function subscale. Eleven items that report confidence in managing arthritis-related symptoms with a 5-point Likert scale. A higher score indicates better self-efficacy.

The Insomnia Severity Index has seven items that report insomnia severity on a 5-point Likert scale. A higher score indicates more severe insomnia.

Pain coping inventory has 33 items that report 6 coping styles on a 4-point Likert scale. The highest number indicates the coping style the participant applies most.

Participants are weighed using their own scale. The weight is recorded in kilograms to track changes over time.

Physical Activity Readiness Questionnaire has seven yes or no questions about health conditions. If any yes answers are giv-en, medical clearance may be needed before starting activity programs. In this study, the question about joint pain is excluded, since all participants will answer yes.

is reported through the Pittsburgh Sleep Quality Index (PSQI). Nineteen items that report sleep quality over the past month on a 4-point Likert scale. A higher score indicates poorer sleep quality.

parameter to change behaviour: "To what extent do you intend to [target behavior]?"

parameter to change behaviour: "Do you find it important to [target behavior]?"

parameter to change behaviour: "I am confident that if I want to, I can [target behavior]"

Session start times, session duration, pages visited per session, total number of clicks, reminders that were opened, reminders that led user to start app, interaction with content items, 5-point Likert scale rating for information in the app.

One yes or no question that evaluates if participants have re-ceived any care in the past month for their osteoarthritis complaints. If they answered yes, participants can choose between a list of healthcare professionals.