Assessing Responsiveness and Determining Minimal Clinically Important Differences In Idiopathic Pulmonary Fibrosis Open Access

Abstract

Introduction: Idiopathic pulmonary fibrosis (IPF) is a progressive lung disease with a median survival of 2-3 years after diagnosis. Current medications have been shown to decrease the decline in lung function but have no impact on patient related outcome measures (PROMs). The aim of this study was to assess the responsiveness of various physiologic measures and PROMs and to estimate Minimal Clinically Important Differences (MCID) values for worsening using anchor based methods. 

Methods: We conducted secondary analyses of three randomized controlled trials (STEP-IPF, ACE-IPF and PANTHER-IPF) 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. Receiver operating curve analysis was used to assess responsiveness between the anchor and ten variables of interest (four physiologic measures and six PROMs) and area under the curve ≥ 0.70 was set as the threshold. To determine the MCID values, we used two anchor-based methods, one proposed by Jaeschke and another by Redelmeier.

Results: Only four variables met the responsiveness criteria: 1) Six minute walk distance (6MWD), 2) St. George’s Respiratory Questionnaire (SGRQ), 3) physical component score of SF-36 (SF-36 PCS), and 4) University of California, San Diego, Shortness of Breath Questionnaire (UCSD SOBQ). The MCID values for 6MWD were -75 meters and -43 meters over 24 weeks using Jaeschke and Redelmeier methods respectively. The MCID values for SF-36 PCS over 60 weeks were -7 using Jaeschke and Redelmeier methods. MCID values for SGRQ over 60 weeks were 11 and 10 using Jaeschke and Redelmeier methods respectively. MCID values for the UCSD SOBQ over 60 weeks were 11 using Jaeschke and Redelmeier methods.

Conclusions: The MCID estimates of 6MWD, SGRQ, SF-36, UCSD SOBQ varied considerably from previously proposed values. A single MCID value may not be applicable across all classes of disease severity or durations of follow-up time. 

Table of Contents

A.   INTRODUCTION………………………………………………………………………………………………….1

B.    BACKGROUND………………………………………………………………………………………………..3

C.    METHODS…………………………………………………………………………………………………………6

D.   RESULTS…………………………………………………………………………………………………………11

E.    DISCUSSION/CONCLUSIONS………………………………………………………………………13

F.    REFERENCES…………………………………………………………………………………………………17

G.   TABLES…………………………………………………………………………………………………………..24

Table 1. Description of the three randomized control trials of idiopathic pulmonary fibrosis in adult patients used for secondary data analysis..................24

Table 2. Baseline characteristics of STEP-IPF patients with Health Transition question (SF2) data at 24 Weeks……………………………………………………………………….26

Table 3. Baseline characteristics of ACE-IPF patients with Health Transition question (SF2) data at 48 weeks………………………………………………………………………..27

Table 4. Baseline characteristics of PANTHER IPF patients with Health Transition question (SF2) data at 60 weeks……………………………………………………….29

Table 5. Change in physiologic and patient reported outcome measures over 24 weeks by Health Transition question (SF2)  categorical responses in patients with idiopathic pulmonary fibrosis in the STEP-IPF trial………………………………………….31

Table 6. Change in physiologic and patient reported outcome measures over 48 weeks by Health Transition question (SF2) categorical responses in patients with idiopathic pulmonary fibrosis in the ACE-IPF trial……………………………………………33

Table 7. Change in physiologic and patient reported outcome measures over 60 weeks by Health Transition question (SF2)  categorical responses in patients with idiopathic pulmonary fibrosis in the PANTHER-IPF trial…………………………………35

Table 8. Anchor-based estimates of Minimal Clinically Important Difference (MCID) for worsening in idiopathic pulmonary fibrosis……………………………………37

About this Master's Thesis

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School	Laney Graduate School
Department	Clinical Research
Degree	M.S.
Submission	Master's Thesis
Language	English
Research Field	Health Sciences, Medicine and Surgery
Keyword	Idiopathic pulmonary fibrosis Minimal clinically important difference
Committee Chair / Thesis Advisor	Greg S. Martin, Emory University
Committee Members	Matthew Magee, Emory University Srihari Veeraraghavan, Emory University Jordan Kempker, Emory University Sushma Cribbs, Emory University

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