Supplementary Material for: Quality of Care and Burden in Patients with Celiac Disease: Results from the German Celiac Registry (GeCeR)

Introduction
European and national Celiac Disease (CeD) guidelines offer an easy pathway to diagnose CeD. The German CeD Registry aimed to assess symptoms and clinical findings before diagnosis, diagnostic delay, care during the diagnostic process, and factors associated with persistence of symptoms.
Methods
Individuals with CeD provided demographic, clinical and healthcare-related information. Participants were divided into four subgroups according to age at diagnosis (>18 or <18 years) and year of diagnosis (before and since 2012). Factors associated with symptoms after at least 1-year on a gluten free diet (GFD) were assessed using multivariate logistic regression.
Results
From 11/2019 to 10/2021, 2333 participants were enrolled. After exclusion of 169 (7.2%), 2164 remained for analysis, thereof 796 (36.8%) were diagnosed <18 years, and 1283 (59.3%) since 2012. Most common symptoms before diagnosis included abdominal pain (83%), bloating (82%), fatigue (78%), and diarrhoea (71%). Diagnostic delay after 2012 was longer in adults than children (median 4.4 years [IQR 1.2-13.0] versus 1.1 [IQR 0.5 - 2.2], respectively) (p<0.001). Guideline-conform diagnoses increased over time. After diagnosis, only 60% received professional dietary counselling. Factors associated with symptoms despite GFD included female gender (OR 1.79 [95%CI 1.34; 2.40], p<0.001), same symptom before diagnosis (OR 3.45 [2.45; 4.96], p<0.001), insufficient information provided at diagnosis (OR 1.25 [1.00; 1.57], p=0.046), and age at diagnosis (per decade) (OR 1.11 [1.04;1.18], p<0.001), but not time since diagnosis.
Conclusions
Our findings revealed deficits in awareness, the diagnostic process, and post-diagnostic care that are linked to decreased clinical improvement over time.