Preoperative evaluation of six-minute walk test in patients with malignant pleural mesothelioma

Figures & data

Table 1. Clinical characteristics and pulmonary function test results (n = 18)

Variable	Number	Mean ± SD (range) or ratio
Age, years		65.8 ± 6.4 (52–76)
Male	N = 16	88.9%
Body mass index, kg/m^2		23.4 ± 3.3 (18.3–29.7)
Smoking history, yes	N = 13	72.2%
Known asbestos exposure	N = 9	50.0%
Performance status, 0/1	N = 17/1
Clinical stage, I/II/III	N = 7/6/5
Histology, epitheloid/biphasic/sarcomatoid	N = 15/2/1
Induction chemotherapy	N = 11	61.1%
Hand grip strength, kgf		33.8 ± 6.0 (21.5–42.3)
6MWD, m		465.9 ± 96.7 (316–651)
Minimum SpO2 during 6MWT, % (N = 17)		93.6 ± 2.7 (86–97)
Desaturation during 6MWT*, yes	N = 5	27.8%
Controlling Nutritional Status score ≥3	N = 3	16.7%
Hemoglobin, g/dL		12.0 ± 1.8 (9.4–15.0)
VC, % predicted		84.3 ± 16.5 (46.8–117.6)
TLC, % predicted		86.6 ± 17.7 (57.3–116.8)
RV, % predicted		96.4 ± 26.5 (53.3–152.2)
FVC, % predicted		83.3 ± 16.9 (48.1–118.1)
FEV1, % predicted		78.7 ± 18.8 (45.1–108.5)
FEV1/FVC, %		74.3 ± 11.5 (42.1–91.5)
DLco, % predicted		93.4 ± 21.9 (56.5–130.3)
DLco/VA, % predicted		98.6 ± 21.4 (64.3–144.6)

Note: Data are given as mean ± SD (range) or number (%).

* Desaturation was defined as a fall in SpO₂ ≥ 4% or SpO₂ < 90% during the 6-min walk test (6MWT). The Controlling Nutritional Status (CONUT) score consists of the serum albumin concentration, total peripheral lymphocyte count, and total cholesterol concentration.

Table 2. Surgical parameters and postoperative outcome (n = 18)

Variable	Number	Mean ± SD (range) or ratio (%)
Surgical technique
Extrapleural pneumonectomy	N = 7	38.9%
Pleurectomy/decortication	N = 11	61.1%
Right-side surgery	N = 10	55.6%
Operation time, min		459.6 ± 159.0 (183–732)
Blood loss during surgery, g		2115 ± 1641 (197–5078)
Red blood cell transfusions, yes	N = 11	61.1%
Timing of extubation, 0/1/2 days after surgery	N = 8/9/1
Length of postoperative ICU stay, days		2.2 ± 1.5 (0–6)
Postoperative day of first walking with support		3.7 ± 2.0 (1–10)
Hospital stay after surgery, days		26.3 ± 26.5 (8–102)
Readmission within 30 days after discharge	N = 1	5.6%
Death within 30 days after surgery	N = 0	0%
One-year survival rate	N = 14	77.8%

Note: Data are given as mean ± SD (range) or number (%).

Table 3. Total postoperative complications

Complication	Minor		Major
	Grade I	Grade II	Grade III	Grade IV
Respiratory failure^a	N = 0	N = 0	N = 4 (2)	N = 4 (2)
Pneumonia	N = 0	N = 1 (0)	N = 0	N = 2 (2)
Empyema	N = 0	N = 0	N = 1 (0)	N = 1 (1)
Atrial fibrillation	N = 0	N = 3 (2)	N = 1 (1)	N = 0
Prolonged air leak ^b	N = 1 (0)	N = 0	N = 1 (0)	N = 0
Wound infection	N = 0	N = 2 (1)	N = 0	N = 0
Recurrent nerve paralysis	N = 1 (0)	N = 0	N = 0	N = 0

Notes: Postoperative complications were graded as either minor (Grade I and II) or major (Grade III and IV) by the Clavien-Dindo classification system. Data are given as number (EPP cases).

^a Respiratory failure involves four Grade IV complications (two CO₂ capture and storage, one acute respiratory distress syndrome, and one alveolar hemorrhage) and four Grade III complications (expectoration discharge disorder).

^b Prolonged air leak involves one Grade I complication (persistent air leak for 13 days) and one Grade III complication (treated with drainage and intrapleural OK432).

Table 4. Correlation between preoperative physical parameters and clinical parameters or postoperative outcomes

Variables	6MWD (n = 18)		Minimum SpO2 during 6MWT (n = 17)		Hand grip strength (n = 16)		PaO2 (n = 18)		PaCO2 (n = 18)
	ρ	p-value	ρ	p-value	ρ	p-value	ρ	p-value	ρ	p-value
Minimum SpO2 during 6MWT	−0.122	0.640 (n = 17)	–	–	–	–	–	–	–	–
Hand grip strength	−0.006	0.983 (n = 16)	−0.230	0.392 (n = 16)	–	–	–	–	–	–
PaO2	0.352	0.152	−0.054	0.838	0.085	0.753	–	–	–	–
PaCO2	0.277	0.266	−0.289	0.260	0.296	0.266	−0.180	0.476	–	–
VC, % predicted	0.216	0.390	0.619	0.008*	−0.306	0.249	0.344	0.163	−0.392	0.107
TLC, % predicted	0.138	0.584	0.493	0.044*	−0.417	0.108	0.373	0.127	−0.395	0.105
Inspiratory capacity	0.507	0.032*	0.163	0.533	−0.243	0.365	−0.006	0.981	0.001	0.997
FEV1, % predicted	0.135	0.593	0.104	0.690	−0.053	0.846	0.032	0.900	−0.348	0.157
DLCO, % predicted	0.470	0.049*	0.429	0.085	−0.329	0.213	0.505	0.033*	−0.296	0.232
Postoperative day of extubation	−0.223	0.374	−0.495	0.044*	−0.124	0.648	−0.171	0.498	0.080	0.752
Postoperative day of first walking with support	0.046	0.857	−0.312	0.224	0.034	0.901	−0.235	0.347	0.170	0.500
Hospital stay after surgery	0.032	0.900	−0.273	0.290	−0.461	0.072	−0.188	0.455	0.067	0.791

Notes: Values (ρ) are Spearman’s rank correlation coefficients.

* Significant correlation (p < 0.05).

Table 5. Comparison of clinical and pulmonary function data with and without major complications defined by Clavien-Dindo grade system

Variable	With major complication (n = 6)	Without (n = 12)	p-value
Age, years	66.7 ± 4.3	65.3 ± 7.3	0.687
Body mass index, kg/m^2	22.1 ± 2.6	24.0 ± 3.4	0.241
Clinical stage I	N = 3 (50.0%)	N = 4 (33.3%)	0.428
Induction chemotherapy	N = 5 (83.3%)	N = 6 (50.0%)	0.316
Hand grip strength, kgf	31.3 ± 7.2	36.4 ± 4.6	0.109
6MWD, m	493.0 ± 120.6	452.4 ± 85.0	0.418
Minimum SpO2 during 6MWT	94 (91–95)	95 (86–97)	0.661
CONUT score	1 (0–3)	1 (0–4)	1.000
Hemoglobin, g/dL	11.0 ± 1.1	12.4 ± 1.9	0.122
VC, % predicted	80.8 ± 6.3	86.0 ± 19.8	0.542
FEV1, % predicted	77.9 ± 12.4	79.1 ± 21.8	0.899
DLco, % predicted	89.2 ± 23.7	95.5 ± 21.7	0.583
Extrapleural pneumonectomy	N = 4 (66.7%)	N = 3 (25.0%)	0.141
Right side surgery	N = 4 (66.7%)	N = 6 (50.0%)	0.437
Operation time, min	533.6 ± 153.2	422.5 ± 154.6	0.169
Blood loss during surgery, g	2906 ± 1808	1719 ± 1471	0.154
Red blood cell transfusion	N = 5 (83.3%)	N = 6 (50.0%)	0.316
Postoperative days of first walking with support	4.5 (3–10)	3 (1–4)	0.033*
ICU stay after surgery, days	3.5 (1–6)	1 (0–3)	0.036*
Hospital stay after surgery, days	51.5 (22–102)	12.5 (8–19)	0.001*

Note: Data are given as mean ± SD, median (range), or number (%).

* Significantly difference (p < 0.05) between groups compared by Mann-Whitney test.