Characterization of Episodes of Irritable Bowel Syndrome Using Ecological Momentary Assessment

OBJECTIVES: Patients with irritable bowel syndrome (IBS) report that symptoms occur as episodes. The nature and frequency of episodes have not been well studied. METHODS: Using modified ecological momentary assessment (EMA), we examined clinical factors attributed to IBS symptom episodes and compared them with nonsymptom episode periods in patients with IBS-D (N = 21), IBS-C (N = 18), or IBS-M (N = 19), and healthy controls (N = 19). Symptoms were rated over 14 days on a visual ordinal scale (VOS: 0-10) randomly in morning, midday, and evening, and at wake up, bedtime, prebowel movement, and postbowel movement. Scores were evaluated for total group and across subgroups and between EMA and daily diary cards on the same day. RESULTS: Subjects (n = 57/59) reported symptom episodes 34% of the time. Episodes showed significantly higher pain levels (3.6 vs. 1.64, P < 0.0001), bloating (4.57 vs. 3.02, P < 0.0001), stress (3.54 vs. 2.59, P < 0.0001), and decreased well-being (5.29 vs. 6.16, P < 0.0001). Episode frequency/2 weeks was greatest for IBS-D (10.7 +/- 7.05) than IBS-C (8.4 +/- 5.76) and IBS-M (7.1 +/- 4.45) (P = nonsignificant). IBS-D also had shorter episodes (9 h 23 min) compared with IBS-M (15 h 01 min) and IBS-C (15 h 25 min) (P < 0.04). Stool frequency and looser consistency were greater with IBS-D and similar between IBS-C and IBS-M. Abdominal pain was the greatest predictor of episode status. Diary card ratings of pain and stool frequency overestimate levels reported by EMA. CONCLUSIONS: Episodes of IBS are associated with greater pain (strongest relationship), bloating, and stress scores, and poorer global well-being. Compared with IBS-D, IBS-C and IBS-M are similar in clinical features. Patients overreport pain and stool frequency by diary compared with EMA.