Effectiveness of an anti-inflammatory diet intervention and cognitive behavioural therapy in endometriosis: protocol for a randomised controlled clinical trial.

introductionTreatment for women with endometriosis is only partially or temporarily effective. Moreover, medical hormonal treatment is associated with debilitating side effects and interferes with fertility, while surgery has a relatively high risk of complications. Meanwhile, women with endometriosis show increasing interest in implementing lifestyle interventions to alleviate symptoms and improve health-related quality of life (HRQoL). Integrating these lifestyle interventions can provide a holistic approach to the treatment of this debilitating disease. However, scientific evidence supporting the effectiveness of these interventions is limited. This study is designed to investigate the effectiveness of two lifestyle interventions and the combination of both: an anti-inflammatory diet intervention (AIDI) could improve immune cell function and reduce inflammation, resulting in improved HRQoL and alleviating pain. In addition, the integration of cognitive behavioural therapy (CBT) aims to provide insight into pain mechanisms and coping with pain, and to assist in sustaining dietary adjustments. METHODS AND ANALYSIS: The Pain in Endometriosis And the Relation to Lifestyle (PEARL) study is a five-arm randomised controlled trial with a pre-post factorial design with two factors: an AIDI and CBT. The study population will consist of 250 premenopausal women, of whom 200 are diagnosed with endometriosis and experience pain symptoms and 50 are healthy controls (HC). Women with endometriosis will be recruited from one academic tertiary and five secondary hospitals in the Netherlands. They will be randomised (1:1:1:1) among four intervention groups: standard care (SC) (SC group), SC and an AIDI (SC + AIDI group), SC and CBT (SC + CBT group), and SC, AIDI and CBT (SC + AIDI + CBT group). Women with endometriosis will visit the hospital twice during the intervention period, at the start (T0) and end (T2) of the 13-week intervention period. HC will not undergo any of the interventions and will have one hospital visit (T0). Participants will complete questionnaires regarding pain symptoms, HRQoL, physical activity level, sleep, diet quality, pain cognitions, and stress at T0 and T2. Furthermore, they are instructed to collect menstrual effluent, a vaginal swab and a faecal sample. During the study visits, peripheral blood will be drawn and scalp hair samples will be taken. The primary outcome is average pain, measured using a numerical rating scale. Secondary outcomes focus on HRQoL, inflammation, immune system characteristics, vaginal- and gut microbiome, and hair cortisol levels. These are considered to reflect potentially underlying mechanisms of the effect of both interventions on the primary outcome. Biological samples and questionnaires of women with endometriosis and HC will be compared to establish the differences in secondary outcomes. ETHICS AND DISSEMINATION: This study protocol has been approved (approval number: NL86247.091.24) by the METC Oost-Nederland from Radboud University Medical Centre on July 11, 2024. Prior to participation, participants are required to provide informed consent. The results will be widely disseminated through scientific peer-reviewed journals, and presentation to a broad audience in scientific meetings, congresses, patient meetings, as well as in policy-relevant forums. TRIAL REGISTRATION NUMBER: NCT06332560.