Minimally important differences were estimated for the Functional Assessment of Cancer Therapy-Colorectal (FACT-C) instrument using a combination of distribution- and anchor-based approaches

Kathleen J Yost, D. Cella, A. Chawla, E. Holmgren, David T Eton, J. Z. Ayanian, D. W. West

Research output: Contribution to journalArticle

109 Citations (Scopus)

Abstract

Objective: To estimate minimally important differences (MIDs) on the Functional Assessment of Cancer Therapy-Colorectal (FACT-C) instrument using anchor- and distribution-based methods. Study Design and Setting: Preliminary MIDs were generated for FACT-C scores based on published results for two samples (n = 60 and n = 63) from the FACT-C validation study. Preliminary MIDs were confirmed using data from a Phase II randomized controlled clinical trial (n = 104) and a population-based observational study (n = 568). MIDs were estimated for the colorectal cancer subscale (CCS); the FACT-C Trial Outcome Index (TOI-C), which is the sum of the CCS, physical well-being, and functional well-being subscales; and the FACT-C total score. Both cross-sectional and longitudinal analyses were used. Results: MIDs were stable across the different patient samples. The recommended MIDs ranged from 2 to 3 points for the CCS, 4 to 6 points for the TOI-C, and 5 to 8 points for the FACT-C total score. Conclusions: MIDs can enhance the interpretability of FACT-C scores, and they can be used to provide a basis for sample size estimation and to determine clinical benefit in combination with other measures of efficacy. General guidelines for estimating MIDs for other FACT instruments are suggested.

Original languageEnglish (US)
Pages (from-to)1241-1251
Number of pages11
JournalJournal of Clinical Epidemiology
Volume58
Issue number12
DOIs
StatePublished - Dec 2005
Externally publishedYes

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Colorectal Neoplasms
Therapeutics
Phase II Clinical Trials
Validation Studies
Sample Size
Observational Studies
Randomized Controlled Trials
Cross-Sectional Studies
Guidelines
Population

Keywords

  • Clinical significance
  • Colorectal cancer
  • Health-related quality of life
  • Minimally important difference

ASJC Scopus subject areas

  • Medicine(all)
  • Public Health, Environmental and Occupational Health
  • Epidemiology

Cite this

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title = "Minimally important differences were estimated for the Functional Assessment of Cancer Therapy-Colorectal (FACT-C) instrument using a combination of distribution- and anchor-based approaches",
abstract = "Objective: To estimate minimally important differences (MIDs) on the Functional Assessment of Cancer Therapy-Colorectal (FACT-C) instrument using anchor- and distribution-based methods. Study Design and Setting: Preliminary MIDs were generated for FACT-C scores based on published results for two samples (n = 60 and n = 63) from the FACT-C validation study. Preliminary MIDs were confirmed using data from a Phase II randomized controlled clinical trial (n = 104) and a population-based observational study (n = 568). MIDs were estimated for the colorectal cancer subscale (CCS); the FACT-C Trial Outcome Index (TOI-C), which is the sum of the CCS, physical well-being, and functional well-being subscales; and the FACT-C total score. Both cross-sectional and longitudinal analyses were used. Results: MIDs were stable across the different patient samples. The recommended MIDs ranged from 2 to 3 points for the CCS, 4 to 6 points for the TOI-C, and 5 to 8 points for the FACT-C total score. Conclusions: MIDs can enhance the interpretability of FACT-C scores, and they can be used to provide a basis for sample size estimation and to determine clinical benefit in combination with other measures of efficacy. General guidelines for estimating MIDs for other FACT instruments are suggested.",
keywords = "Clinical significance, Colorectal cancer, Health-related quality of life, Minimally important difference",
author = "Yost, {Kathleen J} and D. Cella and A. Chawla and E. Holmgren and Eton, {David T} and Ayanian, {J. Z.} and West, {D. W.}",
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T1 - Minimally important differences were estimated for the Functional Assessment of Cancer Therapy-Colorectal (FACT-C) instrument using a combination of distribution- and anchor-based approaches

AU - Yost, Kathleen J

AU - Cella, D.

AU - Chawla, A.

AU - Holmgren, E.

AU - Eton, David T

AU - Ayanian, J. Z.

AU - West, D. W.

PY - 2005/12

Y1 - 2005/12

N2 - Objective: To estimate minimally important differences (MIDs) on the Functional Assessment of Cancer Therapy-Colorectal (FACT-C) instrument using anchor- and distribution-based methods. Study Design and Setting: Preliminary MIDs were generated for FACT-C scores based on published results for two samples (n = 60 and n = 63) from the FACT-C validation study. Preliminary MIDs were confirmed using data from a Phase II randomized controlled clinical trial (n = 104) and a population-based observational study (n = 568). MIDs were estimated for the colorectal cancer subscale (CCS); the FACT-C Trial Outcome Index (TOI-C), which is the sum of the CCS, physical well-being, and functional well-being subscales; and the FACT-C total score. Both cross-sectional and longitudinal analyses were used. Results: MIDs were stable across the different patient samples. The recommended MIDs ranged from 2 to 3 points for the CCS, 4 to 6 points for the TOI-C, and 5 to 8 points for the FACT-C total score. Conclusions: MIDs can enhance the interpretability of FACT-C scores, and they can be used to provide a basis for sample size estimation and to determine clinical benefit in combination with other measures of efficacy. General guidelines for estimating MIDs for other FACT instruments are suggested.

AB - Objective: To estimate minimally important differences (MIDs) on the Functional Assessment of Cancer Therapy-Colorectal (FACT-C) instrument using anchor- and distribution-based methods. Study Design and Setting: Preliminary MIDs were generated for FACT-C scores based on published results for two samples (n = 60 and n = 63) from the FACT-C validation study. Preliminary MIDs were confirmed using data from a Phase II randomized controlled clinical trial (n = 104) and a population-based observational study (n = 568). MIDs were estimated for the colorectal cancer subscale (CCS); the FACT-C Trial Outcome Index (TOI-C), which is the sum of the CCS, physical well-being, and functional well-being subscales; and the FACT-C total score. Both cross-sectional and longitudinal analyses were used. Results: MIDs were stable across the different patient samples. The recommended MIDs ranged from 2 to 3 points for the CCS, 4 to 6 points for the TOI-C, and 5 to 8 points for the FACT-C total score. Conclusions: MIDs can enhance the interpretability of FACT-C scores, and they can be used to provide a basis for sample size estimation and to determine clinical benefit in combination with other measures of efficacy. General guidelines for estimating MIDs for other FACT instruments are suggested.

KW - Clinical significance

KW - Colorectal cancer

KW - Health-related quality of life

KW - Minimally important difference

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