Abstract
Introduction Current medications for idiopathic pulmonary fibrosis (IPF) have not been shown to have impact on patient related outcome measures (PROMs) highlighting the need for accurate Minimal Clinically Important Differences (MCID) values. Recently published consensus standards for MCID studies support using anchor-based over distribution-based methods. The aim of this study was to estimate MCID values for worsening in IPF using only an anchor-based approach.
Methods We conducted secondary analyses of three randomised controlled trials with different inclusion criteria and follow-up intervals. The Health Transition question in the Short Form Health Survey 36 (SF-36) questionnaire was used as the anchor. We used receiver operating curve to assess responsiveness between the anchor and ten variables (four physiologic measures and six PROMs). We used an anchor-based method to determine the MCID values of variables that met the responsiveness criteria (area under the curve≥0.70).
Results Six minute walk distance (6 MWD), the St. George's Respiratory Questionnaire (SGRQ), physical component score of SF-36 (SF-36 PCS), and University of California, San Diego, Shortness of Breath Questionnaire (UCSD SOBQ) met the responsiveness criteria. The MCID value for 6 MWD was −75 meters. The MCID value for SF-36 PCS was −7 points. MCID value for SGRQ was 11points. MCID value for the UCSD SOBQ was 11 points.
Conclusions The MCID estimates of 6 MWD, SGRQ, SF-36, UCSD SOBQ using only anchor-based methods were considerably higher compared to previously proposed values. A single MCID value may not be applicable across all classes of disease severity or durations of follow-up time.
Footnotes
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Conflict of interest: Dr. Kang reports non-financial support from National Center for Advancing Translational Sciences, grants from National Institute of Health, during the conduct of the study.
Conflict of interest: Dr. Veeraraghavan reports personal fees from Boehringer Ingelheim, grants from Fibrogen, grants from Bellerophon, grants from Biogen, grants from Nitto Denko, grants from Pliant, grants from Galapagos, grants from Galecto, outside the submitted work.
Conflict of interest: Dr. Martin reports grants from National Center for Advancing Translational Sciences, grants from National Institute of Biomedical Imaging and Bioengineering, grants from National Institutes of Health, the Office of the Director , personal fees from Genentech, personal fees from Grifols, Inc., outside the submitted work.
Conflict of interest: Dr. Kempker reports grants from Agency for Healthcare Quality and Research , personal fees from Grifols, Inc, outside the submitted work.
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- Received March 3, 2021.
- Accepted July 24, 2021.
- Copyright ©The authors 2021
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