The Experience Sampling Method—Evaluation of treatment effect of escitalopram in IBS with comorbid panic disorder

BACKGROUND: Confirming treatment response in clinical trials for irritable bowel syndrome (IBS) is challenging, due to the lack of biomarkers and limitations of the currently available symptom assessment tools. The Experience Sampling Method (ESM) might overcome these limitations by collecting digital assessments randomly and repeatedly during daily life. This study evaluated differences in change in abdominal pain between real‐time (ie, ESM) and retrospective (ie, Gastrointestinal Symptom Rating Scale [GSRS] and an end‐of‐day symptom diary) measurements, using data of an RCT on escitalopram vs placebo in patients with IBS and comorbid panic disorder. METHODS: Twenty‐nine IBS patients with comorbid panic disorder were included in a 6‐month RCT. The GSRS, diary, and ESM were completed at baseline (t = 0) and after 3 (t = 3) and 6 months (t = 6). Linear mixed models were used. KEY RESULTS: Experience Sampling Method analyses revealed a significant interaction between escitalopram and time, and ESM abdominal pain scores were 1.4 points lower in the escitalopram group compared to placebo at t = 6 (on a 1‐to‐7 scale; P = 0.021). When including the interaction with momentary anxiety, the reduction in abdominal pain scores in escitalopram vs placebo was even more pronounced for higher levels of anxiety. Average GSRS‐ and end‐of‐day abdominal pain scores were not significantly different between escitalopram and placebo at t = 3 and 6. CONCLUSIONS & INFERENCES: Real‐time ESM has the potential to capture treatment response more sensitively compared to a retrospective end‐of‐day GI symptom diary and the GSRS, by taking into account day‐to‐day symptom variability as well as momentary factors that might moderate treatment effect, such as anxiety.