Abstract
Background: Adult irritable bowel syndrome (IBS) has been linked to childhood affluence in population and patient samples. However, this may be due to socio-economic differences in the experience of abdominal pain, since bowel symptoms appear to predominate in the lower social class.We aim to explore the influence of the social class on abdominal pain using population-based data from a New Zealand birth cohort study.
Methods: Participants are members of the Dunedin Multidisciplinary Health and Development Study a longitudinal investigation of health and behaviour in a complete birth cohort. The cohort was assembled in 19723 and has been followed prospectively to age 26 (n = 980). Abdominal pain was defined as ANY pain and pain OFTEN over the preceding 12 months; abdominal pain subtypes were also described as follows: Dysmotility-like, ulcer-like, and diarrheal pain, pain associated with nausea/vomiting and pain associated with constipation. A sixth group pain only included individuals, who reported abdominal pain but none of the associated nonpainful symptoms. Social class was assigned using highest level of completed education as follows: High (university degree), Upper-middle (nondegree, tertiary qualifications), Lower-middle (school certificate) and Low (did not complete school).
Results: Educational social class was significantly associated with ANY abdominal pain in the preceding 12 months (P < 0.001), but not with abdominal pain OFTEN (P = 0.52). The significant trend was characterised as a linear decline in the odds of abdominal pain across decreasing levels of social class, and this persisted following adjustment for sex and occupation at age 26 years (P < 0.001).When individuals with abdominal pain were evaluated, membership of the pain only subgroup was significantly higher among those from the lowest social class (P = 0.02); membership of the Dysmotility-like, ulcer-like, diarrheal and constipation pain subgroups was lower in the lowest social classes, although the overall trends were not significant.
Conclusions: Individuals of low social class experience less abdominal pain and are less likely to report pain in combination with other symptoms.