Psychometric Validation of the EQ-5D-3L in Patients with Nontuberculous Mycobacterial (NTM) Lung Disease Caused by Mycobacterium avium Complex (MAC)

Figures & data

Table 1 Hypothesized Direction and Strength of Correlations Between EQ-5D-3L, SGRQ, and 6MWT

Measure	EQ-5D-3L Dimensions					EQ-5D-3L Score
	Mobility	Self-Care	Usual Activities	Pain/Discomfort	Anxiety/Depression	VAS	Index
SGRQ-Activity	Moderate positive	Weak positive	Moderate positive	Weak positive	Weak positive	Moderate negative	Moderate negative
SGRQ-Impact	Weak positive	Weak positive	Moderate positive	Weak positive	Moderate positive	Moderate negative	Moderate negative
SGRQ-Symptom	Weak positive	Weak positive	Weak positive	Weak positive	Moderate positive	Moderate negative	Moderate negative
SGRQ Total Score	Weak positive	Weak positive	Moderate positive	Weak positive	Weak positive	Moderate negative	Moderate negative
6MWT	Moderate negative	Weak negative	Weak negative	Weak negative	Weak negative	Moderate positive	Moderate positive

Abbreviations: 6MWT, six-minute walk test; EQ-5D-3L, EuroQol 5-dimensional 3-level; SGRQ, St. George Respiratory Questionnaire; VAS, visual analogue scale.

Table 2 EQ-5D-3L Index and VAS Scores at Baseline, Month 3, and Month 6

Visit	Parameter	EQ-5D-3L Index Score	EQ-5D-3L VAS
Baseline	N	331	335
	Mean (SD)	0.82 (0.17)	65.9 (21.4)
	Median (Q1 to Q3)	0.80 (0.80 to 1.00)	70.0 (52.0 to 80.0)
	Range	0.00 to 1.00	4.0 to 100.0
Month 3	N	299	300
	Mean (SD)	0.82 (0.17)	67.7 (19.4)
	Median (Q1 to Q3)	0.80 (0.80 to 1.00)	70.0 (56.5 to 80.0)
	Range	0.20 to 1.00	6.0 to 100.0
Month 6	N	275	275
	Mean (SD)	0.83 (0.17)	68.2 (19.9)
	Median (Q1 to Q3)	0.80 (0.80 to 1.00)	70.0 (55.0 to 83.0)
	Range	0.20 to 1.00	4.0 to 100.0

Abbreviations: EQ-5D-3L, EuroQol 5-dimensional 3-level; N, number of patients; SD, standard deviation; Q1, lower quartile; Q3, upper quartile; VAS, visual analogue scale.

Figure 1 Distribution of responses to each of the EQ-5D-3L items at baseline.

Abbreviation: EQ-5D-3L, EuroQol 5-dimensional 3-level.

Table 3 Test–Retest Reliability of the EQ-5D-3L Items, Index Score, and VAS Score

EQ-5D-3L Item	N	Weighted Kappa	95% CI
Mobility	50	0.54	0.28–0.81
Self-Care	50	1	1–1
Usual Activities	50	0.72	0.50–0.94
Pain/Discomfort	50	0.50	0.26–0.74
Anxiety/Depression	50	0.60	0.35–0.85
EQ-5D-3L Scores	N	ICC	95% CI
EQ-5D-3L Index	50	0.80	0.68–0.88
EQ-5D-3L VAS	50	0.85	0.75–0.91

Abbreviations: CI, confidence interval; EQ-5D-3L, EuroQol 5-dimensional 3-level; ICC, intraclass correlation coefficient; VAS, visual analogue scale.

Figure 2 EQ-5D-3L index scores across known groups defined based on (A) 6MWT and (B) ppFEV₁.

Abbreviations: 6MWT, six-minute walk test; EQ-5D-3L, EuroQol 5-dimensional 3-level; ppFEV₁, percent predicted forced expiratory volume in 1 second.

Table 4 Spearman Correlations Between EQ-5D-3L, SGRQ, and 6MWT

Measure	EQ-5D-3L Single Item Dimensions					EQ-5D-3L Score
	Mobility	Self-Care	Usual Activities	Pain/Discomfort	Anxiety/Depression	VAS	Index Score
SGRQ-Activity	0.36	0.19	0.35	0.25	0.17	−0.43	−0.55
SGRQ-Impact	0.28	0.13	0.29	0.26	0.19	−0.48	−0.61
SGRQ-Symptom	0.26	0.10	0.26	0.24	0.13	−0.39	−0.44
SGRQTotal Score	0.34	0.17	0.34	0.29	0.20	−0.50	−0.62
6MWT	−0.23	−0.14	−0.28	−0.19	−0.13	0.31	0.39

Notes: Higher scores on SGRQ and EQ-5D-3L items indicate worse symptoms. Higher 6MWT and EQ-5D index and VAS scores indicate better health-related quality of life. All correlations were statistically significant at α = 0.05.

Abbreviations: 6MWT, 6-minute walk test; EQ-5D-3L, EuroQol 5-dimensional 3-level; SGRQ, St. George’s Respiratory Questionnaire; VAS, visual analogue scale.

Table 5 Point Biserial Correlations and Guyatt Responsiveness Statistics for EQ-5D-3L Index Scores by Each of the Anchors

Anchor	Point Biserial Correlations	Mean Change in Responders’ Scores	SD of Change in Non-Responders’ Scores	Guyatt Statistic
Culture Conversion	0.04	0.00	0.13	−0.01
ppFEV1	0.03	0.00	0.09	0.03
6MWT	0.11	0.01	0.10	0.08
SGRQ	0.21	0.03	0.10	0.29

Abbreviations: 6MWT, 6-minute walk test; SD, standard deviation; SGRQ, St. George’s Respiratory Questionnaire; ppFEV₁, percent predicted forced expiratory volume in 1 second.