Economic living standard and abdominal pain mediate the association between functional gastrointestinal disorders and depression or anxiety

BACKGROUND: Functional gastrointestinal disorders (FGIDs) are common and cause significant morbidity. Psychiatric comorbidities associated with FGIDs include anxiety and depression. However, little is understood about the factors that modulate this association. The aim of this study was to examine the association between FGIDs and depression and anxiety, and to determine the covariates influencing this association in a New Zealand cohort. METHODS: The Christchurch IBS cOhort to investigate Mechanisms FOr gut Relief and improved Transit (COMFORT) study is an observational case–control study that recruited FGID cases and healthy controls between 2016 and 2018. In addition to the collection of a wide range of biological samples, participants completed questionnaires concerning socioeconomic status, physical activity, smoking, alcohol intake, anxiety, and depression (the latter two measured using the Hospital Anxiety and Depression Score [HADS]). A multivariate analysis was performed using the significant covariates from the univariate analyses to test whether their effect was independently significant on anxiety and depression. KEY RESULTS: A total of 315 participants (57 with diarrhea‐predominant IBS (IBS‐D), 30 with constipation‐predominant IBS (IBS‐C), 41 with mixed‐IBS (IBS‐M), 16 with functional diarrhea (FD), 42 with functional constipation (FC), and 129 controls); mean age 53 years (range 18–70 years), 221 (70%) female) completed the questionnaires. Anxiety (odds ratio [OR] 2.85 [95% confidence interval [CI] 1.64–4.94, p < 0.01) and depression (OR 3.40 [95% CI 1.35–8.55, p = 0.01]) were strongly associated with FGID cases versus controls. Lower economic living status (p < 0.01) was an independent covariate associated with depression, while lower economic living status (p < 0.005) and abdominal pain (p = 0.005) were both independently associated with anxiety. CONCLUSIONS & INFERENCES: In addition to the established associations between FGIDs and anxiety and depression, we have shown that the economic standard of living, pain, and IBS phenotype are significant independent covariates. This study demonstrates the range of lifestyle and demographic factors that modulate morbidity associated with FGIDs and may provide targets for intervention.