Stefan Elbers

205 General discussion SCOPE OF THE THESIS The World Health Organization (2017) defines rehabilitation as: An integrative strategy that aims at empowering persons with health conditions who are experiencing or are likely to experience disability so that they can achieve and maintain optimal functioning, a decent quality of life and inclusion in the community and society. This research project focused on one particular aspect of this definition in the context of IMPT programmes: the maintenance of positive treatment gains, in order to prevent relapse. In line with this definition, we consider that effective treatment is not only determined by the level of functioning and wellbeing at the end of the programme, but also by the ability of patients to transfer key principles to their own personal situations and to retain them over time. The main rationale for starting this research project was the premise that this topic has been neglected for decades, combined with empirical indications that relapse is likely to occur after chronic pain rehabilitation (Morley, 2008; Turk & Rudy, 1991; Wood & Neal, 2016). An additional reason to explore this topic is the rising popularity of self-management interventions. These aim to increase self-efficacy and to support patients in actively and autonomously coping with their chronic disease (Van de Velde et al., 2019). Given the absence of studies directly related to relapse prevention after chronic pain treatment, we expected that self-management programmes – which often include components such as action planning and problem-solving (Lorig, 2015) – would incorporate valuable insights in how to enhance maintenance of gains. SUMMARY OF MAIN FINDINGS Our first aim was to provide an overview of the current state of research on treatment characteristics and longitudinal outcomes of IMPT programmes. In Chapter 2 ,we identified 74 patient cohorts that included at least a baseline and one follow-up measurement at 12 months post-treatment. This allowed us to analyse the longitudinal development of nine different outcome measures. The large majority of the calculated pre-post contrasts across these measures indicated that participation in IMPT programmes is associated with improvements in wellbeing. Importantly, in most cohorts this improvement is maintained over time. This finding differs from the typical triangular relapse patterns that have been observed in other health behaviour change interventions (Wood & Neal, 2016). Furthermore, the data extraction procedure that was based on current standards of outcome reporting (Hoffmann et al., 2014) provided insight into the various study, patient selection and treatment approaches. By using the TIDieR checklist, we were able to