Introduction We have previously shown that a twin with IBS was more likely to have a mother with IBS than a co-twin with IBS. This may be because learned illness behaviour in childhood is as important as genetic factors in the aetiology of IBS. We have examined the association of learned illness behaviour with IBS in our twin cohort.
Methods 6552 unselected twins were asked to complete a validated questionnaire including the social learning of illness scale. IBS was categorised by Rome III criteria into 3 groups: extended criteria IBS, limited criteria IBS (symptoms more than once a week) and a medical IBS diagnosis.
Results 4128 subjects replied (63%). 3349 were evaluable (91% female, median age 62 (IQR 53–69)). Univariate analysis revealed that only a medical diagnosis of IBS was associated with an increasing score on the social learning of illness scale (Table 1). Other factors associated with all three sub-types of IBS were increasing psychosomatic score, anxiety, female gender, younger age and having a parent with IBS. Social learning of illness behaviour and all these factors were independently associated with a medical diagnosis of IBS. Modelling of illness behaviour (OR 1.06, 95% CI 1.01–1.12, p = 0.04) and reinforcement of the sick role (1.1, 95% CI 1.01–1.2, p = 0.04) were found to be significant predictors of a medical diagnosis of IBS. However, encouragement of the sick role was not associated with a medical diagnosis of IBS.
Conclusion A higher score for social learning of illness behaviour was associated with a medical diagnosis of IBS. This was independent of other risk factors for IBS. In our twin cohort, the aspects of learned illness behaviour which influenced the development of IBS were reinforcement of the sick role and modelling of illness behaviour. Social learning of illness behaviour did not appear to influence IBS as defined by Rome III criteria when a medical diagnosis was not made, suggesting that it drives health care seeking behaviour rather than necessarily being an aetiological factor for IBS.
Disclosure of Interest None Declared