Global Prevalence of Adherence to Gluten-Free Diet in Patients With Celiac Disease: A Systematic Review and Meta-Analysis

INTRODUCTION: Strict and life-long gluten-free diet (GFD) is the standard of care for patients with celiac disease (CeD). Maintenance of adherence to GFD is the key to the success of GFD; however, a proportion of patients are unable to maintain strict adherence to GFD. METHODS: We performed a systematic review and meta-analysis to estimate the pooled prevalence of adherence of GFD, as assessed by celiac dietary adherence test, BIAGI score, standardized dietitian evaluation or self-reported adherence to GFD, in patients with CeD after at least 1 year of initiating GFD. Electronic reference databases were searched from January 1, 1990 to April 30, 2025. Overall, 69 studies including 27,641 subjects were found eligible for pooling estimates by objective assessment methods. The pooled effect size (95% confidence interval [CI]) was calculated using a random effect model. RESULTS: Most of the studies had low risk of bias and there was no publication bias. The pooled prevalence of adherence to GFD as assessed by objective methods of assessment and self-reported adherence were 64% (95% CI 59%-69%) and 74% (95% CI 69%-79%), respectively. Specifically adherence rates were 65% (95% CI 57%-73%) with standardized dietitian evaluation, 57% (95% CI 50%-64%) with celiac dietary adherence test and 75% (95% CI 65%-83%) with BIAGI score. Highest adherence rates were reported from European and North American countries. There was no significant difference in the adherence rates with time or age of the participants. On univariate metaregression, method of assessment of adherence affected the rate of adherence to GFD. DISCUSSION: One in 3 patients with CeD is unable to maintain a good adherence to GFD. There is need to develop strategies to improve the adherence to GFD.