Association of the 6-minute walking test ratio and difference with pulmonary function in patients with interstitial lung disease

Article Figures & Data

Download figure
Open in new tab
Download powerpoint
Figure 1
- Associations of 6MWT ratio with relevant variables. A) Associations of 6MWT ratio with PO₂. B) Associations of 6MWT ratio with actual/predicted FVC. C) Associations of 6MWT ratio with actual/predicted FEV1. D) Associations of 6MWT ratio with FEV1/ FVC. E) Associations of 6MWT ratio with DLCO. F) Associations of 6MWT ratio with actual/predicted DLCO.
Download figure
Open in new tab
Download powerpoint
Figure 2
- Associations of 6MWT difference with relevant variables. A) Associations of 6MWT difference with PO₂. B) Associations of 6MWT difference with FeNO. C) Associations of 6MWT difference with actual/predicted FVC. D) Associations of 6MWT difference with actual/predicted FEV1. E) Associations of 6MWT difference with FEV1/FVC. F) Associations of 6MWT difference with DLCO. G) Associations of 6MWT difference with actual/predicted DLCO.

Table 1

- Baseline patient characteristics.

Characteristic	Total (n=137)
Age (years)	63 (35,93)
Height (cm)	163 (145,184)
Body weight (kg)	64 (45,95)
Hospital stays (days)	9 (1,20)
Gender
Male	71 (51.8)
Female	66 (48.2)
Diagnosis
Connective tissue-related lung disease	42 (30.9)
Idiopathic interstitial pneumonia	29 (21.3)
Granulomatous disease	3 (2.2)
Unknown interstitial disease	62 (45.6)
Oxygen inhalation in daily living	42 (30.7)
Using crutches in daily living	3 (2.2)
Oxygen inhalation in examinations	2 (1.5)
Using crutches in examinations	2 (1.5)
Blood-gas analysis
PO₂ (mmHg)	79.2±14.4
PCO₂ (mmHg)	38.9 (27.6,78.1)
FeNO (ppb)	17.5 (5,69)
Pulmonary function
Actual value of FVC (L)	2.46±0.76
Ratio of actual/predicted FVC, %	80.46±21.25
Actual value of FEV1 (L)	1.97±0.57
Ratio of actual/predicted FEV1, %	80.32±19.40
FEV1/FVC, %	80.94±7.30
TLC (L)	4.00±1.00
Ratio of actual/predicted TLC, %	70.75 (35.0,112.0)
DLCO (mmoL/min.kPa)	4.48±1.51
Ratio of actual/predicted DLCO, %	57.85±18.94
Six-min walking test
Predicted value (m)	518.9±60.7
Actual value (m)	449 (169.5,694)
Actual value/predicted value, %	85.7±17.6
Predicted value – actual value	73.9±95.1

PO₂: partial pressure of oxygen, PCO₂: partial pressure of carbon dioxide, FeNO: exhaled nitric oxide, FVC: forced vital capacity, FEV1: forced expiratory volume in 1 s, TLC: total lung capacity, DLCO: diffusing capacity of the lungs for carbon monoxide. Data are presented as median (min, max), mean±standard deviation, or n (%)

Table 2

- Associations of 6MWT difference and 6MWT ratio with relevant variables.

Characteristic	6MWT ratio		6MWT difference
Characteristic	r	P-value	r	P-value
PO₂	0.205	0.018	-0.173	0.047
PCO₂	-0.119	0.172	0.101	0.247
FeNO	0.266	0.062	-0.290	0.041
Actual value of FVC	0.130	0.130	-0.077	0.373
Actual value/predicted value of FVC	0.184	0.034	-0.203	0.019
Actual value of FEV1	0.106	0.221	-0.049	0.574
Actual value/predicted value of FEV1	0.173	0.046	-0.197	0.023
FEV1/FVC	-0.204	0.017	0.202	0.018
TLC	0.071	0.414	-0.033	0.704
Actual value/predicted value of TLC	0.073	0.407	-0.093	0.290
DLCO	0.303	<0.001	-0.273	0.001
Actual value/predicted value of DLCO	0.355	<0.001	-0.363	<0.001

6MWT: 6-minute walking test, PO₂: partial pressure of oxygen, PCO₂: partial pressure of carbon dioxide, FeNO: exhaled nitric oxide, FVC: forced vital capacity, FEV1: forced expiratory volume in 1 s, TLC: total lung capacity, DLCO: diffusing capacity of the lungs for carbon monoxide