Table 1 Overview of the HIPPROCLIPS-trial studies

1

To determine the influence of traumatic experiences and mental disorders on the pain processing of individuals with hip OA and shortly after THA

1. To which extent are traumatic experiences and mental disorders associated with preoperative pain processing in individuals with hip OA waiting for THA?

2. To which extent are traumatic experiences and mental disorders associated with pre- and early postoperative pain-related cognitions and emotions in individuals with hip OA undergoing THA?

- Traumatic experiences (T0)

- Mental disorders (T0)

Primary: QST (T0)

Secondary: Pain-related cognitions and emotions, other pain-related variables (T0, T1)

Design: cross-sectional (RQ1) and longitudinal analysis (RQ2)

Main statistical method: LASSO regression

2

To identify preoperative clinical phenotypes in individuals with hip OA and their prognosis for outcomes in pain and disability after THA

1. Which clinical phenotypes exist in individuals with hip OA waiting for THA, based on a set of biopsychosocial characteristics?

2. What is the prognostic value of these clinical phenotypes for outcomes in pain and disability after THA?

- Sociodemographic and biomedical information (T0)

- Pain-related cognitions and emotions (T0)

- Traumatic experiences (T0)

- Mental disorders (T0)

- Self-efficacy (T0)

- Social support (T0)

- Perceived stress (T0)

- QST (T0)

- Other pain-related variables (T0)

Primary: HOOS

Secondary: NPRS, PBM, SF-36, PSFS, GPE, Satisfaction, Muscle Strength

Design: Cross-sectional analysis of baseline data

Main statistical method: Decision Tree learning

3

To identify pre- and early postoperative prognostic factors for long-term outcomes in pain and disability after THA in individuals with hip OA

1. To which extent do pre-operative traumatic experiences, mental disorders, pain-related cognitions and emotions, self-efficacy, social support, and central pain mechanisms predict long-term postoperative pain and disability after THA for hip OA?

2. To which extent do early postoperative pain-related cognitions and emotions predict long-term pain and disability after THA for hip OA?

- Pain-related cognitions and emotions (T0)

- Traumatic experiences (T0)

- Mental disorders (T0)

- Self-efficacy (T0)

- Social support (T0)

- QST (T0)

Primary: HOOS

Secondary: NPRS, PBM, SF-36, PSFS, GPE, Satisfaction, Muscle Strength

Design: longitudinal prospective Main statistical method: Gradient Boosting Algorithms

4

To identify postoperative clinical phenotypes based on biopsychosocial characteristics at different timepoints up to one year after THA for hip OA

1. Which postoperative clinical phenotypes exist based on biopsychosocial characteristics at different timepoints up to one year after THA for hip OA?

2. What is the relationship between preoperative and postoperative clinical phenotypes in individuals with hip OA and after THA?

3. To which extent do pre- and early postoperative factors predict the belonging to a clinical phenotype after THA?

- Sociodemographic and biomedical information (T2, T3, T4)

- Pain-related cognitions and emotions (T2, T3, T4)

- Traumatic experiences (T2, T3, T4)

- Mental disorders (T2, T3, T4)

- Self-efficacy (T2, T3, T4)

- Social support (T2, T3, T4)

- Perceived stress (T2, T3, T4)

- QST (T2, T3, T4)

- Other pain-related variables (T2, T3, T4)

Primary: HOOS

Secondary: NPRS, PBM, SF-36, PSFS, GPE, Satisfaction, Muscle Strength

Design: longitudinal prospective Main statistical method: Recurrent Neural Networks