Quality of Life and Gluten-Free Diet Adherence in Adult Patients with Celiac Disease: A Cross-Sectional Questionnaire Study

Background: Celiac disease is a chronic autoimmune enteropathy whose only established treatment is a strict, lifelong gluten-free diet (GFD). Beyond physical symptoms, the disease and its dietary management affect emotional, social, and economic functioning. Objectives: This study aimed to assess health-related quality of life (HRQoL) in adult patients with celiac disease and to identify factors associated with their daily functioning and adherence to the GFD. Methods: A cross-sectional survey was conducted between February and March 2026 among 101 adults with a self-reported diagnosis of celiac disease made by a gastroenterologist, recruited through online support groups. Data were collected using an author-designed sociodemographic questionnaire, the Gastrointestinal Quality of Life Index (GIQLI), and the Celiac Dietary Adherence Test (CDAT). Analyses (Mann–Whitney U and Kruskal–Wallis tests, repeated-measures ANOVA, Spearman correlations with false-discovery-rate correction, and multivariable linear and logistic regression with prespecified sensitivity analyses) were performed in R 4.5.2, with α = 0.05. Results: The most frequently reported difficulties were eating away from home, the high cost of the GFD, and limited product availability; the most common symptoms after inadvertent gluten exposure were abdominal pain, bloating, fatigue, diarrhea, and headache. HRQoL was lowest in the emotional and physical domains. Better dietary adherence was significantly correlated with higher HRQoL across the total score and all domains except the social domain, whose weak internal consistency in this sample (α = 0.57) precludes substantive interpretation (total GIQLI: ρ = −0.50; p < 0.001), and in the multiple regression, adherence remained the strongest independent correlate of HRQoL (β = −0.36; adjusted R2 = 0.41). Longer time on the diet was independently associated with better adherence (adjusted OR = 0.55 per duration category; p = 0.017). In a small vocational education subgroup (n = 8), poorer adherence and lower HRQoL were observed relative to participants with higher education, though only the HRQoL difference survived correction for multiple testing (FDR-adjusted p = 0.011 vs. 0.060 for adherence); given the size of this subgroup, this comparison is exploratory and hypothesis-generating. Higher HRQoL was also associated with milder symptoms, better-rated medical care, greater product availability, and higher household income. Conclusions: In this sample, HRQoL scores were lowest in the emotional and physical domains; because the design was cross-sectional and included no comparison group, these data characterize the distribution of HRQoL within the sample and do not establish that celiac disease reduces HRQoL. Dietary adherence was the strongest correlate of patient functioning, alongside symptom burden, self-rated quality of medical care, and product availability. Because the design is cross-sectional, these associations do not establish direction, and whether comprehensive health education and psychological support improve outcomes requires prospective and interventional evaluation.