Somatization an independent psychosocial risk factor for irritable bowel syndrome but not dyspepsia: a population-based study

Background: A psychosocial conceptualization for irritable bowel syndrome and unexplained dyspepsia has been proposed, but remains untested. We conducted a comprehensive population-based study to determine what psychiatric and psychosocial factors, if any, are important in irritable bowel syndrome and dyspepsia. Methods: Two hundred and seven participants identified from two previous Australian population surveys who also met Rome I criteria for irritable bowel syndrome (n=156) or unexplained dyspepsia 0=511) were included in the study. Consulters (n = 103) were those who had had visited their general practitioner for gastrointestinal symptoms at least once in the prior 12 months. Nonconsulters had not sought medical care for gastrointestinal symptoms in the past year. Controls (n=100) did not report having any abdominal pain in a previous population survey. Psychosocial variables were assessed using structured interviews and validated self-report measures. Results: Psychiatric diagnoses, neuroticism, more highly threatening life event stress, an external locus of control and ineffectual coping styles were significantly associated with having a diagnosis of irritable bowel syndrome and/or dyspepsia. Only somatization (odds ratio=5.28, 95% confidence interval 1.57-17.68), however, was independently associated with irritable bowel syndrome. Psychosocial factors did not discriminate between consulters and nonconsulters. Conclusions: Somatization is likely play a key role in explaining irritable bowel syndrome but not dyspepsia.