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Psychometric validation of patient-reported outcome measures assessing chronic constipation

Authors Nelson L, Williams V, Fehnel S, Carson R, MacDougall J, Baird M, Tourkodimitris S, Kurtz C, Johnston J

Received 24 March 2014

Accepted for publication 11 June 2014

Published 26 September 2014 Volume 2014:7 Pages 385—394

DOI https://doi.org/10.2147/CEG.S64713

Checked for plagiarism Yes

Review by Single-blind

Peer reviewer comments 2


Lauren M Nelson,1 Valerie SL Williams,1 Sheri E Fehnel,1 Robyn T Carson,2 James MacDougall,3 Mollie J Baird,3 Stavros Tourkodimitris,2 Caroline B Kurtz,3 Jeffrey M Johnston3

1RTI Health Solutions, Durham, NC, USA; 2Forest Research Institute, Jersey City, NJ, USA; 3Ironwood Pharmaceuticals, Cambridge, MA, USA

Background: Measures assessing treatment outcomes in previous CC clinical trials have not met the requirements described in the US Food and Drug Administration's guidance on patient-reported outcomes.
Aim: Psychometric analyses using data from one Phase IIb study and two Phase III trials of linaclotide for the treatment of chronic constipation (CC) were conducted to document the measurement properties of patient-reported CC Symptom Severity Measures.
Study methods: Each study had a multicenter, randomized, double-blind, placebo-controlled, parallel-group design, comparing placebo to four doses of oral linaclotide taken once daily for 4 weeks in the Phase IIb dose-ranging study (n=307) and to two doses of linaclotide taken once daily for 12 weeks in the Phase III trials (n=1,272). The CC Symptom Severity Measures addressing bowel function (Bowel Movement Frequency, Stool Consistency, Straining) and abdominal symptoms (Bloating, Abdominal Discomfort, Abdominal Pain) were administered daily using interactive voice-response system technology. Intraclass correlations, Pearson correlations, factor analyses, F-tests, and effect sizes were computed.
Results: The CC Symptom Severity Measures demonstrated satisfactory test–retest reliability and construct validity. Factor analyses indicated one factor for abdominal symptoms and another for bowel symptoms. Known-groups F-tests substantiated the discriminating ability of the CC Symptom Severity Measures. Responsiveness statistics were moderate to strong, indicating that these measures are capable of detecting change.
Conclusion: In large studies of CC patients, linaclotide significantly improved abdominal and bowel symptoms. These psychometric analyses support the reliability, validity, discriminating ability, and responsiveness of the CC Symptom Severity Measures for evaluating treatment outcomes in the linaclotide clinical studies.

Keywords: psychometric evaluation, patient-reported outcomes, linaclotide

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