Prevalence and etiologies of non-responsive celiac disease: A systematic review and meta-analysis.

Background and aim: Non-responsive celiac disease (NRCD) is defined as ongoing symptoms despite 6-12 months of gluten-free diet (GFD), the only known treatment for celiac disease (CeD). There is inconsistency in studies describing the proportion of patients having NRCD and its various causes among patients with CeD. We therefore conducted a systematic review and meta-analysis to determine the prevalence and causes of NRCD.

Methods: The PubMed, Embase, Cochrane Library, Scopus, and Web of Science databases were searched for original studies reporting the proportion of patients with persistent symptoms after ≥ 6 months of GFD. Studies reporting the etiologies of NRCD were also identified. The systematic review was conducted as per the Meta-analysis of Observational Studies in Epidemiology guidelines. Statistical analysis was performed in STATA.

Results: Of 2965 search results, nine studies met the inclusion and exclusion criteria. Five studies (n = 4414) reported data on prevalence, and seven studies (n = 790) reported the causes of NRCD. The pooled prevalence of NRCD was 22% (95% confidence interval, 11-35%). Among patients with NRCD, inadvertent exposure to gluten was the most common cause (33%), followed by functional gastrointestinal disorders including irritable bowel syndrome in 16%. Refractory CeD type II along with its premalignant and malignant sequelae was observed in 7% of patients with NRCD.

Conclusion: One in five patients with CeD may not respond to GFD and would likely be classified as NRCD. Inadvertent gluten exposure was the cause of ongoing symptoms in one-third of patients with NRCD. Improving adherence to GFD along with developing novel therapeutics to mitigate symptoms due to ongoing gluten exposure is critical.