Minimal clinically important difference in idiopathic pulmonary fibrosis

Mohleen Kang; Lucian Marts; Jordan A. Kempker; Srihari Veeraraghavan

doi:10.1183/20734735.0345-2020

Tables

Table 1

Summary of commonly used anchor-based methods

Method	Explanation	Comment
Jaeschke	Mean (C_follow-up−C_baseline)	Regression to the mean
Mean change, Redelmeier	Mean (C_follow-up−C_baseline)–Mean (U_follow-up−U_baseline)	Regression to the mean
Receiver operating curve	Cut-off point where sensitivity+specificity is maximised between changed and unchanged	Non-parametric Random sample variation Change analysed separately for worsening and improvement
Regression modelling	Transition variable^# as independent or dependent variable	Control for confounding and effect modification

C_follow-up: follow-up score of patients who are changed based on response to anchor; C_baseline: baseline score of patients who are changed based on response to anchor; U_follow-up: follow-up score of patients who are unchanged based on response to anchor; U_baseline: baseline score of patients who are unchanged based on response to anchor. ^#: transition variable (usually coded as 1 if changed based on response to anchor or 0 if unchanged based on anchor).

Table 2

Summary of MCID values of physiological and patient-reported outcome measures in patients with IPF

Variable	Author [ref.]	Time period weeks	Sample size (disease severity)	Anchors	Distribution method used	Improvement or deterioration	MCID value
FVC % pred	Du Bois [14]	48	1156 (mild-to-moderate)	SF-2 Hospitalisation Death	Yes	Both	2–6%
6MWD m	Du Bois [18]	48	826 (mild-to-moderate)	Hospitalisation Death	Yes	Both	24–45^#
	Nathan [19]	48	338 (mild-to-moderate)	Hospitalisation Death	Yes	Both	21.7–37.0^#
	Swigris [20]	52	123 (mild-to-moderate)	FVC SGRQ	Yes	Both	28
ISW m	Nolan [37]	8	77 patients^¶	GRCQ	Yes	Improvement	31–46^#
Total SGRQ	Swigris [22]	26	129 (mild-to-moderate)	FVC TDI	Yes	Both	7 (5–10)⁺
Total SGRQ	Swigris [23]	52	1061 (mild-to-moderate)	FVC UCSD SOBQ PGI-C	Yes	Both	4–5
SGRQ-I	Prior [24]	52	124 (mild-to-moderate)	FVC D_LCO 6MWD GRCS UCSD SOBQ SGRQ	No	Improvement	3.9
SGRQ-I	Prior [24]	52	124 (mild-to-moderate)	FVC D_LCO 6MWD GRCS UCSD SOBQ SGRQ	No	Deterioration	4.9
UCSD SOBQ	Swigris [25]	24	180 (severe)	SGRQ-A	Yes	Both	8 (5–11)⁺
SF-36	Swigris [22]	26	129 (mild-to-moderate)	FVC	Yes	Both	3 (MCS)
	Swigris [22]	26	129 (mild-to-moderate)	TDI	Yes	Both	3 (PCS)
	Witt [27]	^§	258^¶	6MWD FVC D_LCO	Yes	Both	6 (MCS)
	Witt [27]	^§	258^¶	6MWD FVC D_LCO	Yes	Both	5 (PCS)
KBILD	Prior [24]	52	124 (mild-to-moderate)	FVC D_LCO 6MWD GRCS UCSD SOBQ SGRQ	No	Improvement	4.7
KBILD	Prior [24]	52	124 (mild-to-moderate)	FVC D_LCO 6MWD GRCS UCSD SOBQ SGRQ	No	Deterioration	2.7

SGRQ-I: SGRQ for patients with IPF; SF-36: Short-Form Health Survey 36; SF-2: health transition question in SF-36 questionnaire; GRCQ: Global Rating of Change Questionnaire; TDI: Transition Dyspnea Index; PGI-C: Patient's Global Impression of Change; D_LCO: diffusing capacity of the lung for carbon monoxide; GRCS: Global Rating of Change Scales; SGRQ-A: SGRQ activity domain; MCS: mental component score; PCS: physical component score. ^#: range; ^¶: no set inclusion criteria based on disease severity; ⁺: point estimate (range); ^§: no a priori follow-up time.