What level of IBS symptoms drives impairment in health-related quality of life in community subjects with irritable bowel syndrome? Are current IBS symptom thresholds clinically meaningful?

Background: Quality of life is impaired in some people with IBS, but the level of symptoms that may drive this impairment is unclear. Aims: We aimed to identify whether current frequency and severity cut-offs for IBS-type symptoms are associated with a clinically meaningful impairment of quality of life in the community. Methods: People who met modified Rome III criteria for IBS (n = 201) and controls (n = 1,904) were assessed. Frequency of IBS symptoms was grouped a priori into 'less frequent' (not at all and sometimes) and 'more' frequent (often, very often and almost always). Severity of abdominal pain was grouped into 'mild' (very mild and mild) and severe (moderate, severe and very severe). Mental and physical functioning was measured using the valid SF-12, with 'normal' functioning (defined as a score of >43 and >48) and 'impaired' functioning (defined as a score of ≤43 and ≤48), respectively. Psychological variables were assessed via valid self-report. Results: Having 'more' versus 'less' severe abdominal pain (OR = 9.41; 95% CI 1.17-75.43, P = 0.03) and 'more' versus 'less' frequent diarrhoea (OR = 2.19; 95% CI 1.13-4.26, P = 0.02) along with increasing age (OR = 1.03; 95% CI 1.01-1.05, P = 0.003) were significant independent predictors of having impairment in physical functioning. In terms of psychological factors, having higher levels of depression (OR = 1.61; 95% CI 1.36-1.91) and somatic distress (OR = 1.17; 95% CI 1.09-1.27) were independently associated with mental and physical impairment, respectively. Conclusion The current frequency and severity threshold cut-offs for IBS symptoms in the Rome III criteria are associated with a clinically meaningful impairment of quality of life in community subjects with IBS.