LAUSR

Previous studies have reported explanatory models of health-related quality of life (HRQoL) in patients with Crohn disease or inflammatory bowel disease. However, no model for HRQoL has been developed that is specialised for patients with ulcerative colitis (UC). In this study, we aimed to develop and evaluate a predictive explanatory model for HRQoL among outpatients with UC in Japan. We conducted a cross-sectional survey between December 2019 and July 2020 at a clinic in Japan. HRQoL was evaluated using the 32-item Inflammatory Bowel Disease Questionnaire (IBDQ-32). We extracted explanatory variables of HRQoL, including disease activity, psychological symptoms, and social support, from previous studies and created an explanatory model based on the conceptual model of Wilson & Cleary (1995). The relationship between explanatory variables and the IBDQ-32 total score was examined using the Spearman’s rank correlation coefficient, Mann–Whitney test, or Kruskal–Wallis test. We conducted multiple regression analysis and path analysis to examine the effect of explanatory variables on IBDQ-32 total score. We included a total of 203 patients with UC. Variables that were significantly associated with the IBDQ-32 total score were partial Mayo Score, presence or absence of treatment side effects, Hospital Anxiety and Depression Scale (HADS) score, and having/not having an adviser when patients were severely ill-conditioned. HADS had the largest negative effect on IBDQ-32 total score (β = −0.474), followed by partial Mayo Score (β = −0.408), presence/absence of treatment side effects (β = −0.116), having/not having an adviser when patients were ill-conditioned (β = 0.081). Having an adviser or not when ill-conditioned had an indirect effect on patients’ IBDQ-32 total score via HADS (β = −0.111). We verified the final model, which included IBDQ-32 total score and the above four explanatory variables (adjusted R² = 0.501, GFI = 0.996, AGFI = 0.970, CFI = 1.000, RMSEA = 0.010, AIC = 28.043). Psychological symptoms had the most direct effect on HRQoL in patients with UC and acted as a mediator in the relationship between social support and HRQoL. Nursing interventions to improve HRQoL in patients with UC should consider the effect of psychological symptoms and support when patients are severely ill-conditioned.