Symptom-association probability between meal ingestion and abdominal pain in patients with irritable bowel syndrome. Does somatization play a role?

Background: Patients with irritable bowel syndrome (IBS) complain of postprandial abdominal pain, but it is still unknown how much of this association is due to chance. Somatization enhances the perception of symptoms after a meal. We assessed: (i) the proportion of meal-related pain periods and the symptom-association probability (SAP) between the two variables in IBS patients; and (ii) how this association is affected by somatization. Methods: Seventy IBS patients recorded the times of meals and abdominal pain in a 10-day diary card. The proportion of postmeal pain periods was calculated in relation to the total number of 90-min periods with pain. Fisher's exact test was used to calculate the probability (p) of an association within a time window of 90 min, and the SAP was calculated as (1 - p) × 100%. The IBS Symptom Severity Scale, the SCL90-R for psychological symptoms, and the SF-36 for the quality of life were completed. Key Results: The proportion of postmeal pain periods was 42 ± 27%. SAP was significant (p < 0.05) in 32 patients (45%). Somatization was altered in 30 patients (47%), who were younger and had more severe IBS and a poorer quality of life. Somatization did not influence the association between meal ingestion and abdominal pain. Conclusions & Inferences: Meal ingestion and abdominal pain are significantly associated in 45% of IBS patients. Somatization influences IBS severity and the patients' quality of life, but not the strength of the association between eating and pain. Patients with IBS often claim that meal ingestion worsens abdominal pain. The findings of this study demonstrate that these two variables are significantly (p < 0.05) associated in 45% of patients. Somatization is a frequent and clinically relevant psychological alteration in patients with IBS. The results of this study confirm that the syndrome is more severe in patients with altered somatization, whose quality of life is impaired. However, somatization does not influence the association between meal ingestion and abdominal pain.