Historically, measures of symptom severity of irritable bowel syndrome with constipation (IBS-C) in clinical trials have not met the evidence requirements described in the FDA guidance on patient-reported outcomes (PROs).
The FDA describe the evidentiary requirements and review criteria for patient-reported outcome measures intended to support product approval or labelling claims.
Dr Williams and colleagues from North Carolina, USA analyzed data from 2 phase 3 trials of linaclotide for the treatment of IBS-C to evaluate the psychometric properties of patient-reported outcome measures assessing changes in the severity of abdominal and bowel symptoms.
|The psychometric analysis results strongly support the reliability of the IBS-C Symptom Severity Measures|
|Alimentary Pharmacology & Therapeutics|
A set of patient-reported outcome assessments addressing abdominal and bowel symptoms, the IBS-C Symptom Severity Measures, were administered daily using interactive voice response system technology.
The IBS-C Symptom Severity Measures showed highly satisfactory test–retest reliability, and construct validity.
The team identified 1 factor for abdominal symptoms and another for bowel symptoms.
Known-groups F-tests comparing subgroups based on various responder definitions were statistically significant and in the expected direction, substantiating the discriminating ability of the IBS-C Symptom Severity Measures.
The team demonstrated that responsiveness statistics were capable of detecting change.
Dr Williams' team concludes, "The psychometric analysis results strongly support the reliability, construct validity, discriminating ability and responsiveness of the IBS-C Symptom Severity Measures and substantiate the conclusion of linaclotide treatment benefit."