TY - JOUR
T1 - The PAC-SYM questionnaire for chronic constipation
T2 - defining the minimal important difference
AU - Yiannakou, Y.
AU - Tack, J.
AU - Piessevaux, H.
AU - Dubois, D.
AU - Quigley, E. M.M.
AU - Ke, M. Y.
AU - Da Silva, S.
AU - Joseph, A.
AU - Kerstens, R.
N1 - Funding Information:
These analyses were funded by Shire International GmbH, Zug, Switzerland. Writing support was provided by Katie Pillidge, PhD, of PharmaGenesis London, London, UK, and funded by Shire.
Publisher Copyright:
© 2017 Shire International GMBH. Alimentary Pharmacology & Therapeutics published by John Wiley & Sons Ltd.
PY - 2017/12
Y1 - 2017/12
N2 - Background: The Patient Assessment of Constipation-Symptoms (PAC-SYM) questionnaire is frequently used in clinical trials of constipation. However, the threshold for reduction in total PAC-SYM score used to define a clinical response on this 0-4 point scale has not undergone formal appraisal, and its relationship with clinical benefit as perceived by patients has not been defined. Aim: To determine the minimal important difference in PAC-SYM score, and the optimum cut-off value for defining responders. Methods: The minimal important difference was estimated using data from six international phase 3/4, double-blind, randomised controlled trials of prucalopride in patients with chronic constipation (NCT01147926, NCT01424228, NCT01116206, NCT00485940, NCT00483886, NCT00488137), with anchor- and distribution-based approaches. Five appropriate patient-reported outcomes were selected as anchors. In addition, receiver operating characteristics (ROC) curve analyses were used to investigate responder discrimination for each anchor. Results: Data from 2884 patients were included. Minimal important difference estimates ranged from –0.52 to –0.63 across the five anchors. Estimates were not affected by study location but were consistently lower for rectal symptoms than for abdominal and stool symptoms. Distribution-based estimates were considerably lower than anchor-based estimates. ROC curve analyses showed optimum cut-off scores for discriminating responders to be similar to anchor-based minimal important difference estimates. Conclusions: Anchor-based methods gave consistent results for the minimal important difference, at approximately –0.6, and this value was close to the ROC-determined optimal cut-off scores for responder discrimination. This value could be considered in clinical practice. A slightly more conservative threshold (eg –0.75) could be used in clinical trials to reduce the placebo response rate.
AB - Background: The Patient Assessment of Constipation-Symptoms (PAC-SYM) questionnaire is frequently used in clinical trials of constipation. However, the threshold for reduction in total PAC-SYM score used to define a clinical response on this 0-4 point scale has not undergone formal appraisal, and its relationship with clinical benefit as perceived by patients has not been defined. Aim: To determine the minimal important difference in PAC-SYM score, and the optimum cut-off value for defining responders. Methods: The minimal important difference was estimated using data from six international phase 3/4, double-blind, randomised controlled trials of prucalopride in patients with chronic constipation (NCT01147926, NCT01424228, NCT01116206, NCT00485940, NCT00483886, NCT00488137), with anchor- and distribution-based approaches. Five appropriate patient-reported outcomes were selected as anchors. In addition, receiver operating characteristics (ROC) curve analyses were used to investigate responder discrimination for each anchor. Results: Data from 2884 patients were included. Minimal important difference estimates ranged from –0.52 to –0.63 across the five anchors. Estimates were not affected by study location but were consistently lower for rectal symptoms than for abdominal and stool symptoms. Distribution-based estimates were considerably lower than anchor-based estimates. ROC curve analyses showed optimum cut-off scores for discriminating responders to be similar to anchor-based minimal important difference estimates. Conclusions: Anchor-based methods gave consistent results for the minimal important difference, at approximately –0.6, and this value was close to the ROC-determined optimal cut-off scores for responder discrimination. This value could be considered in clinical practice. A slightly more conservative threshold (eg –0.75) could be used in clinical trials to reduce the placebo response rate.
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U2 - 10.1111/apt.14349
DO - 10.1111/apt.14349
M3 - Article
C2 - 28983926
AN - SCOPUS:85032654910
SN - 0269-2813
VL - 46
SP - 1103
EP - 1111
JO - Alimentary Pharmacology and Therapeutics
JF - Alimentary Pharmacology and Therapeutics
IS - 11-12
ER -