Psychosocial distress and somatic symptoms in community subjects with irritable bowel syndrome: a psychological component is the rule

Abstract

Objectives: Psychosocial factors may drive people with irritable bowel syndrome (IBS) to seek health care, but whether psychological factors are causally linked to IBS is controversial. One hypothesis is that IBS is a heterogeneous syndrome comprising two distinct conditions, one psychological and the other biological. However, it is unclear how many people with IBS in the community have little somatization and minimal psychosocial distress. The aim of our study was to estimate the proportion of people with IBS in a representative US community, who have low levels of somatic and psychological symptoms.

Methods: The cohort comprised subjects from three randomly selected population studies from Olmsted County, Minnesota. All of them filled out a validated gastrointestinal (GI) symptom questionnaire, the Symptom Checklist-90-R (SCL-90-R), and the Somatic Symptom Checklist (SSC) comprising 11 somatic complaint items. Logistic regression models were used to evaluate the associations between somatic symptoms/psychosocial factors and IBS, adjusting for age and gender.

Results: Of the 501 eligible subjects, 461 (92%) provided complete data (mean age=56 years, 49% female). IBS (Rome II criteria) was associated with both higher SSC and Global Severity Index (GSI of SCL-90-R) scores. Among subjects with high (75th percentile) SSC scores, 43% reported IBS vs. 10% of those with low (<25th percentile) SSC scores. Among those with high (60) GSI scores, 23% reported IBS vs. 6% with low (<40) GSI scores. Specifically, none of the IBS subjects had both low SSC and low GSI scores.

Conclusions: Psychological factors and somatization are strongly associated with IBS in the community. However, IBS may not be related to low psychological distress and/or somatization.

Figure 1

Algorithm of pooled data from three population-based studies.

Figure 2

Distribution of subjects with and without irritable bowel syndrome (IBS) according to the Somatic Symptom Checklist (SSC) and the Global Severity Index (GSI) of SCL-90-R. * 0.18 Is the 25th percentile of SSC distribution; ^‡ 0.77 Is the 75th percentile of SSC distribution; ^† GGSI scores were transformed into standardized T scores with a mean of 50 and s.d. of 10.