Psychological Pathways From Disease Activity to Quality of Life in Ulcerative Colitis and Crohn's Disease: A Cross‐Sectional Serial Mediation Study

AIM: To examine whether psychological distress and self-efficacy serially mediate the relationship between disease activity and quality of life in patients with ulcerative colitis and Crohn's disease. DESIGN: A cross-sectional study. METHODS: We included 525 hospitalized patients with inflammatory bowel disease (224 with ulcerative colitis, 301 with Crohn's disease). Disease activity was assessed using the Mayo Score for ulcerative colitis and the Crohn's Disease Activity Index for Crohn's disease. Psychological distress was measured using the 7-item Generalized Anxiety Disorder scale and the 9-item Patient Health Questionnaire. Self-efficacy was measured using the Inflammatory Bowel Disease Self-Efficacy Scale, and quality of life using the 32-item Inflammatory Bowel Disease Questionnaire. Serial mediation models with bias-corrected bootstrapping were constructed separately for each disease subtype, adjusting for covariates. RESULTS: Higher disease activity was associated with worse quality of life in both groups. Self-efficacy mediated this association in both diseases. Psychological distress was a mediator in ulcerative colitis only. Replacing clinical scores with C-reactive protein and faecal calprotectin rendered all indirect effects non-significant. CONCLUSION: Self-efficacy is a universal mediator across inflammatory bowel disease subtypes. Psychological distress is disease-specific to ulcerative colitis. The pathway is driven by subjective symptom perception, not objective inflammation. IMPLICATIONS FOR THE PROFESSION AND/OR PATIENT CARE: Nurses should enhance self-efficacy through self-management support for all patients, and assess anxiety and depression in those with ulcerative colitis. IMPACT: This study clarifies distinct psychological pathways from disease activity to quality of life in ulcerative colitis and Crohn's disease, providing evidence for subtype-tailored nursing interventions. Reporting Method This study is reported in accordance with STROBE guidelines. PATIENT OR PUBLIC CONTRIBUTION: No patient or public involvement.