Stefan Elbers

72 Chapter 3 MAIN TEXT Characteristics of the base review Weperformed the initial reviewinSeptember 2020 (theprotocolwas registered inPROSPERO under CRD42018076093) to identify the change in outcomes over time and the between- study heterogeneity for interdisciplinary pain treatment programs for patients with chronic pain. All longitudinal study designs such as case series and RCTs were considered. Our main reason for including more study types than RCTs was that carefully controlled inclusion criteria and treatment procedures do often not reflect the heterogeneous reality of clinical practice in the domain of rehabilitation (Morley et al., 2013; Rowbotham et al., 2013; Smeets, 2021; Wade et al., 2010). In addition, many treatment programs disseminate their results through case series, which contain important information regarding the change over time. The abstract screening, full-text selection, data extraction, and risk of bias assessment was performed in duplicate. Primary studies were eligible if they included IMPT programs as intervention for patients with chronic primary pain that was primarily perceived in musculoskeletal structures. Furthermore, studies had to include a baseline and a follow-up assessment of at minimum 12 months post treatment for at least one of the outcomes of interest: Physical function, pain interference, self-efficacy, depression, anxiety, anger, general emotional function, social role functioning and pain intensity. We assessed Risk of Bias with the JBI critical appraisal checklist for case series. Our data analysis included the change over time per outcome, by calculating standardized mean differences between pre, post and final follow-up timepoints. LSR protocol A LSR starts with a baseline systematic review that is in line with PRISMA guidelines (Counotte et al., 2018; Elliott et al., 2017). In addition, there should be a study protocol that includes a rationale for maintaining a LSR as well as planned methodological and statistical approaches that are in line with multiple iterations over time (Elliott et al., 2017). For example, repeating meta-analyses at each update may inflate type I error and should be taken into account (Simmonds et al., 2017). When the decision was made for the transition of this systematic review into a living systematic review, we submitted a new study protocol in PROSPERO (CRD42021247142). We chose to create a new record instead of updating the record of the base review, because the workflow and iterative nature of the living review are substantially different. The main rationale for this living systematic review was to provide and maintain an up-to- date overview of all interdisciplinary pain treatment programs that include one of our outcomes of interest for at least 12 months. Other reasons included a faster inclusion of