Impact of functional gastrointestinal disorders on health-related quality of life: a population-based case-control study

Background: The health-related quality of life is impaired in patients with functional gastrointestinal disorders seen in referral centres. Aim: To determine whether the health-related quality of life is impaired in subjects with functional disorders in the community and whether any differences can be explained by psychological co-morbidity. Methods: In a population-based, nested, case-control study, subjects reporting symptoms of either dyspepsia or irritable bowel syndrome and healthy controls were interviewed and completed a battery of psychological measures plus a validated, generic, health-related quality of life measure (Medical Outcomes Study 36-item short form health survey, SF-36). The association between irritable bowel syndrome and dyspepsia and the physical and mental composite scores of SF-36 were assessed with and without adjustment for psychological state. Results: One hundred and twelve cases (30 dyspepsia, 39 irritable bowel syndrome, 32 dyspepsia and irritable bowel syndrome and 11 gastrointestinal symptoms but not dyspepsia or irritable bowel syndrome) and 110 controls were enrolled. In the unadjusted linear regression models, irritable bowel syndrome (but not dyspepsia) was negatively associated with the physical composite score (P < 0.05); in an adjusted model, the association between the physical health-related quality of life and irritable bowel syndrome was explained by the Symptom Checklist-90 somatization score alone. In unadjusted models, irritable bowel syndrome and dyspepsia were each negatively associated with the mental composite score (P < 0.05). The association between the mental health-related quality of life and dyspepsia remained after adjusting for psychological covariates, but the association between this and irritable bowel syndrome was not significant after adjustment. Conclusions: In the community, health-related quality of life is impaired in subjects with irritable bowel syndrome and dyspepsia; however, much of this association can be explained by psychological factors.