title: Psychometric assessment of the IBS-D Daily Symptom Diary and Symptom Event Log.
abstract: Diarrhea-predominant irritable bowel syndrome (IBS-D) can considerably impact patients' lives. Patient-reported symptoms are crucial in understanding the diagnosis and progression of IBS-D. This study psychometrically evaluates the newly developed IBS-D Daily Symptom Diary and Symptom Event Log (hereafter, "Event Log") according to US regulatory recommendations.
  
  
  
  A US-based observational field study was conducted to understand cross-sectional psychometric properties of the IBS-D Daily Symptom Diary and Event Log. Analyses included item descriptive statistics, item-to-item correlations, reliability, and construct validity.
  
  
  
  The IBS-D Daily Symptom Diary and Event Log had no items with excessive missing data. With the exception of two items ("frequency of gas" and "accidents"), moderate to high inter-item correlations were observed among all items of the IBS-D Daily Symptom Diary and Event Log (day 1 range 0.67-0.90). Item scores demonstrated reliability, with the exception of the "frequency of gas" and "accidents" items of the Diary and "incomplete evacuation" item of the Event Log. The pattern of correlations of the IBS-D Daily Symptom Diary and Event Log item scores with generic and disease-specific measures was as expected, moderate for similar constructs and low for dissimilar constructs, supporting construct validity. Known-groups methods showed statistically significant differences and monotonic trends in each of the IBS-D Daily Symptom Diary item scores among groups defined by patients' IBS-D severity ratings ("none"/"mild," "moderate," or "severe"/"very severe"), supporting construct validity.
  
  
  
  Initial psychometric results support the reliability and validity of the items of the IBS-D Daily Symptom Diary and Event Log.
authors.affiliation: Psychometrician, Leland, NC, USA.
authors.forename: Kathleen
authors.initials: K
authors.lastname: Rosa
authors.affiliation: Astellas Pharma Global Development, Inc., 1 Astellas Way, Northbrook, IL, 60062, USA. Leticia.Delgado-Herrera@astellas.com.
authors.forename: Leticia
authors.initials: L
authors.lastname: Delgado-Herrera
authors.affiliation: Astellas Pharma Global Development, Inc., 1 Astellas Way, Northbrook, IL, 60062, USA.
authors.forename: Bernie
authors.initials: B
authors.lastname: Zeiher
authors.affiliation: Adelphi Values, Boston, MA, USA.
authors.forename: Benjamin
authors.initials: B
authors.lastname: Banderas
authors.affiliation: Adelphi Values, Bollington, UK.
authors.forename: Rob
authors.initials: R
authors.lastname: Arbuckle
authors.affiliation: AbbVie, North Chicago, IL, USA.
authors.forename: Glen
authors.initials: G
authors.lastname: Spears
authors.affiliation: Clinical Outcomes Solutions, Tucson, AZ, USA.
authors.forename: Stacie
authors.initials: S
authors.lastname: Hudgens
mesh_terms: D000328:Adult; D003430:Cross-Sectional Studies; D003967:Diarrhea / Q000453:epidemiology*; D005260:Female; D006801:Humans; D043183:Irritable Bowel Syndrome / Q000453:epidemiology*; D008297:Male; D008875:Middle Aged; D000071066:Patient Reported Outcome Measures; D011594:Psychometrics / Q000379:methods*; D015203:Reproducibility of Results; D018434:Sickness Impact Profile
keywords: Diarrhea-predominant IBS; IBS-D; Patient-reported outcome; Psychometric analysis