Stefan Elbers

181 AGRIPPA: protocol for an RCT period. Each treatment location is also required to provide a research assistant who is not involved with the treatment progamme. This research assistant will be responsible for performing the treatment allocation procedure. Recruitment All patients who will start an IMPT progamme during the study inclusion period will be contacted by their treating physician in rehabilitation medicine and will receive a patient information letter. The patient will then have 1 to 2 weeks to consider participation and to ask any additional questions before signing the informed consent form. Instruction of the app will follow when a signed informed consent form has been provided to the research assistant. An independent research counselor will be available to all participating patients for any questions and general support during the study. Her email address will be provided via the patient information letter. Randomization In participating treatment centers, treatment progammes either consist of group sessions, individual sessions, or their combination. To prevent contamination, we will perform group randomization when treatment is predominantly provided in groups. When treatment is provided in individual sessions, we will randomize each patient individually using a simple randomization procedure. The randomization will be performed using random allocation cards based on computer-generated random numbers. The randomization procedure will be executed by a research assistant who is not providing treatment, and will be concealed from health care providers and patients using a set of sequentially numbered opaque and sealed envelopes. The group randomization procedure will be performed in a similar manner for each group that contains at least one participating patient. Interventions Standard Treatment. Although there is variation in the content of each treatment progamme, they all adopt a similar biopsychosocial perspective on pain management (Dutch Pain Society & Samenwerkingsverband Pijnpatiënten naar één stem, 2017; Gatchel et al., 2014). Furthermore, each progamme includes (cognitive) behavioural treatment modalities (e.g., graded activity, exposure in vivo, acceptance and commitment therapy) as well as pain neuroscience education, active patient involvement, and structured team meetings to coordinate treatment and evaluate each patient’s progress. All progammes are supervised by a physician in rehabilitation medicine who is responsible for patient screening, assessment, and monitoring of overall progress. The treatment team always includes a psychologist and a physical therapist or occupational therapist. At each location, patients start with pain education, where a biopsychosocial orientation toward pain will