Exploring the Interplay Between Catastrophizing and Endometriosis Pain Through Two-Wave and Intensive Longitudinal Data.

Background: Endometriosis, characterized by the presence of endometrial-like tissue outside the uterus, results in chronic pelvic pain. However, lesion characteristics alone cannot fully explain the complexity of endometriosis-related pain. Pain catastrophizing, a cognitive process that influences pain perception, has traditionally been studied through cross-sectional or two-wave designs, which struggle to capture its dynamic interplay with endometriosis pain. To address these gaps, our study explores the bidirectional relationship between pain catastrophizing and pain outcomes-including intensity, frequency, and flares-over a detailed four-week period, an aggregated 30-day timeframe, and across sensory and affective dimensions.

Methods: A Latent Growth Curve Model assessed the relationship between pain catastrophizing, initial pain levels, and endometriosis pain trajectories over four weeks. Additionally, four mediator models explored how baseline pain catastrophizing affects various pain aspects, including sensory and affective dimensions, and its subsequent influence on pain catastrophizing.

Results: Results indicate that high levels of pain catastrophizing significantly escalate endometriosis pain over four weeks, affecting average pain intensity, episode frequency, and flares over 30 days. Pain catastrophizing also adversely impacts sensory and affective dimensions. These elements partially mediate baseline pain catastrophizing's effect on week five levels, revealing a bidirectional relationship. Notably, while the affective dimension amplifies subsequent pain catastrophizing, the sensory dimension exerts a contrasting negative influence.

Conclusion: The study highlights the bidirectional influence between pain catastrophizing and several aspects of endometriosis-related pain. Sensory and affective dimensions play distinct roles, with implications for personalized interventions. Limitations and clinical relevance are discussed.