Objectives: Clinical observation showed that there is family aggregation in constipated subjects, but formal data are lacking. This prompted us to conduct a formal family study in constipated subjects.
Methods: Constipated subjects (probands) were identified according to the Rome II and Chinese constipation questionnaire criteria, healthy subjects were chosen as controls. Living first-degree relatives (parents, siblings, and children) and spouses (as internal controls) from both groups were identified. The questionnaire on Rome II criteria was given to the relatives either through the index subjects or by mail. The questionnaire was received by mailing back or through the index subjects. Any nonresponders were chased.
Results: There were 132 probands with constipation and 114 controls. The Rome II questionnaire was sent to a total of 677 relatives of the probands and 591 of the controls. Relatives were comparable in mean age, sex distribution, family size, and marital status in the two groups. Constipation prevalence was 16.4% in probands' relatives versus 9.1% in controls' relatives, i.e., 13% in the relatives from both proband and controls. Among the constipated relatives, 6.3%versus 9.3% of the relatives were spouses of the probands and controls (P = 0.5). Subjects with more family members having constipation will have higher risk of constipation: OR 2.02, CI 1.14-3.65, P = 0.0177 for at least one family member; OR 3.99, CI 1.86-9.23, P = 0.0006 for at least two family members.
Conclusions: Familial aggregation of constipation occurs, supporting a genetic or intrafamilial environment component.