515: Illness Invalidation in Endometriosis Is Linked to Poorer Quality of Life and Mental Defeat

Topic: Clinical Science
Subtopic: Pain category (ICD-11), Chronic primary visceral / pelvic pain, Psychology

Background and Aims: Endometriosis is a common gynaecological condition, yet experiences of symptom minimisation and dismissal by healthcare professionals, family and workplaces are widely reported. Illness invalidation may undermine psychological wellbeing and worsen health-related quality of life (HRQoL); however, its impact and mechanisms remain under-researched. We examined associations between invalidation and two clinically relevant outcomes: endometriosis-specific HRQoL and mental defeat (MD; feeling defeated in response to symptoms). We compared HRQoL and MD in high vs low invalidation groups across medical, family and work contexts; tested whether invalidation predicted outcomes beyond symptom/psychological covariates; and tested MD as a mediator between invalidation and HRQoL.

Methods: Ethical approval was granted (University of Oxford; Ref: MS IDREC 709824). A cross-sectional online survey via Qualtrics (July–October 2025) recruited UK adults (≥18) with endometriosis confirmed by surgery and/or imaging, via social media advertisements circulated by UK endometriosis charities/support groups and workplace posters. Outcomes were HRQoL (Endometriosis Health Profile-30) and MD (adapted Pain Self-Perception Scale). Illness invalidation (Illness Invalidation Inventory; 3*I) was assessed across medical, family and work contexts; covariates were symptom severity, symptom duration, pain catastrophising, anxiety and depression. Between-group comparisons used t-tests with Bonferroni adjustment. Hierarchical regression and PROCESS (5,000 bootstraps) assessed covariate-adjusted effects and mediation.

Results: Analysed overall sample N=399; group Ns varied by invalidation context. High illness invalidation (vs low) was associated with poorer HRQoL and greater MD across medical, family and work contexts (all between-group comparisons p<.001; d=.50–.76). Medical: HRQoL Welch’s t(234.4)=−6.50, d=.73; MD t(397)=−6.60, d=.69. Family: HRQoL Welch’s t(306.2)=−4.90, d=.50; MD t(395)=−5.70, d=.61. Work: HRQoL Welch’s t(338.2)=−6.40, d=.67; MD t(349)=−7.10, d=.76. In complete-case adjusted regressions, invalidation explained unique variance in MD (ΔR²=.033) and HRQoL (ΔR²=.025). Medical, family and work invalidation independently predicted MD; medical and family invalidation independently predicted poorer HRQoL. Indirect effects via MD were non-significant.

Conclusions: Illness invalidation was independently associated with poorer endometriosis-specific HRQoL and greater mental defeat after accounting for symptom burden, anxiety, depression and pain catastrophising. Across invalidation contexts, medical invalidation showed the strongest independent association with HRQoL, while family invalidation also contributed uniquely; all three invalidation contexts independently predicted mental defeat. Mental defeat did not mediate the invalidation-HRQoL association in adjusted models, suggesting that other mechanisms may explain this pathway. Improving patient experiences of healthcare is likely to require system-level changes (e.g. clear care pathways, accessible information, timely follow-up), alongside validating clinical interactions. Longitudinal and qualitative studies are needed to establish causality and guide service improvement.

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Presenting Author: Emma Evans
Submitting Author: Bethany Carr

Senior Author: Emma Evans

IASP 2026 Global Year theme of Neuropathic Pain: No

• Dr Emma Evans - University of Oxford
• Dr Judith Kalthoff - University of Oxford