Prevalence, symptoms and risk factor profile of rumination syndrome and functional dyspepsia: a population-based study.

BACKGROUND: Rumination syndrome is a functional gastroduodenal disorder characterised by effortless regurgitation of recently ingested food. Emerging evidence reports duodenal eosinophilic inflammation in a subset, suggesting a shared pathophysiology with functional dyspepsia (FD). AIM: To assess the clinical features of rumination syndrome and FD in a community-based study. METHODS: We mailed a survey assessing gastrointestinal symptoms, diet and psychological symptoms to 9835 residents of Olmsted County, MN, USA in 2017-2018; diagnostic codes were obtained from linked clinical records. The two disorders were assessed as mutually exclusive in 'pure' forms with a separate overlap group, all compared to a control group not meeting criteria for either. Prevalence of associations, and univariate and independent associations with predictors were assessed by logistic regression. RESULTS: Prevalence of rumination syndrome and FD were 5.8% and 7.1%, respectively; the overlap was 3.83-times more likely than expected by chance. Independent predictors for rumination (odds ratio (OR), 95% confidence interval (CI)) were female gender (1.79, 1.21-2.63), smoking (1.89, 1.28-2.78), gluten-free diet (1.58, 1.14-2.19), allergic rhinitis (1.45, 1.01-2.08) and depression (1.10, 1.05-1.16). FD was independently associated with female gender, depression, non-coeliac wheat sensitivity, migraine, irritable bowel syndrome and somatic symptoms. A similar reported efficacy (≥54%) of low fat or dairy-free diets was found with both disorders (P = 0.53 and P = 1.00, respectively). The strongest independent associations with overlapping FD and rumination syndrome were a history of rheumatoid arthritis (3.93, 1.28-12.06) and asthma (3.02, 1.44-6.34). CONCLUSION: Rumination syndrome overlaps with FD with a shared risk factor profile, suggesting a common pathophysiology.

Identification and validation of functional gastrointestinal disorder subtypes using latent class analysis: a population-based study.

OBJECTIVE: Attempts to categorize distinct functional gastrointestinal disorders based on reported symptoms continue but symptoms frequently overlap. The study objective was to use latent class analysis (LCA) which accommodates both continuous and discrete manifest variables to determine mutually exclusive subgroup assignments of a population-based sample using gastrointestinal symptom and patient data. MATERIALS AND METHODS: A validated bowel disease questionnaire and somatic symptom questionnaire were mailed to an age and gender stratified randomly selected community sample. Responses to the symptom questions were dichotomized as frequent vs. infrequent based on Rome IV criteria. A LCA model was developed using a calibration subset and the results applied to the validation subset. RESULTS: There were 3831 total respondents (48%) with 3425 having complete data. The LCA algorithm was run for each of 10 (random) splits of the dataset and 2-6 latent classes were specified. Using the values of Akaike's Information Criterion coefficient c to determine fit of the data, 4 latent classes yielded better values resulting in four subgroups: 'asymptomatic,' 'upper' abdominal symptoms, 'lower' abdominal symptoms, and 'mixed' (upper and lower abdomen). CONCLUSIONS: Latent class analysis identified 4 groups based on symptoms. This approach resulted in differentiation by anatomical region rather than the Rome IV classification of symptoms.