Guided internet-based self-help treatment based on acceptance and commitment therapy (ACT) for endometriosis-related chronic pain - a Single Case Experimental Design (SCED) with tailored measurements

Endometriosis is a chronic, estrogen-dependent inflammatory disease affecting approximately 10% of women of reproductive age. Despite medical treatments such as hormone therapy and surgery, pain and other symptoms often persist, highlighting the need for complementary treatment methods. Research on psychological treatment options are limited, particularly internet-based interventions. Acceptance and Commitment Therapy (ACT), a variant of Cognitive Behavioral Therapy (CBT), has shown effectiveness in treating various types of chronic pain, including internet-delivered ACT (iACT). However, further research is needed to evaluate its efficacy specifically for endometriosis-related pain. There is also a growing demand for more individualized treatment approaches. One way to improve treatment effectiveness is by focusing on specific psychological processes and selecting the most suitable ones for each individual, using statistical analyses. This approach could enhance treatment efficiency and reduce the burden on both patients and healthcare systems. The research project consists of two phases: (1) a traditional manual-based iACT treatment (current OSF registration) and (2) an individualized version of iACT with three levels of customization (future OSF registration). The study aims to examine the effects of these treatments on pain interference, quality of life, and other aspects of chronic pain, as well as evaluate the feasibility of treatment adaptation and participants’ experiences. The study employs four single-case experimental designs (SCED), of which one is described in detail in this registration, and includes idiographic analyses to gain a detailed understanding of individual treatment outcomes. Another key goal is to explore patients’ experiences with the treatment through interviews conducted shortly after completion and three months later to identify helpful and hindering factors. Research questions 1. Is manual-based iACT for endometriosis-related chronic pain efficacious in increasing endometriosis-related functional level and psychological flexibility, as well as improving quality of life, and depressive symptoms? 2. How do individuals with endometriosis experience a manual-based iACT treatment for endometriosis symptoms? 3. How do individuals with endometriosis experience the same treatment three months after the treatment has ended?