The Long-Term Prognostic Significance of 6-Minute Walk Test Distance in Patients with Chronic Heart Failure

Table 4

Bootstrap model based on 1000 stratified samples. Univariable predictors listed in order of magnitude of 𝑃 value.

Variables	𝐵	Bootstrap
		Bias	SE	P value	95% CI
					Lower	Upper
Log NT pro-BNP	0.489	−0.001	0.35	0.001	0.418	0.556
6-MWT (m)	−0.002	0.0001	0.0001	0.001	−0.002	−0.001
Age (years)	0.042	−0.001	0.004	0.001	0.033	0.050
NYHA class	0.136	0.004	0.060	0.023	0.027	0.263
Diastolic BP (mmHg)	−0.007	0.0001	0.003	0.030	−0.013	−0.001
Haemoglobin (g·dL^−1)	−0.041	−0.002	0.021	0.049	−0.082	0.002
Urea (mmol·L^−1)	0.024	−0.002	0.014	0.068	−0.006	0.047
Sodium (mmol·L^−1)	−0.014	−0.001	0.010	0.182	−0.034	0.007
QRS duration (m·s^−1)	0.001	0.0001	0.001	0.253	−0.001	0.004
Systolic BP (mmHg)	0.001	0.0001	0.002	0.528	−0.002	0.005
Creatinine (u·moL^−1)	0.001	0.0001	0.001	0.667	−0.001	0.004
Heart rate (beats·min^−1)	0.000	0.0001	0.002	0.736	−0.002	0.005
Potassium (mmol·L^−1)	−0.001	0.0001	0.073	0.982	−0.143	0.137

SE: standard error; 95% CI: 95% confidence intervals; 6-MWT: 6-minute walk test; NYHA: New York Heart Association; LVI: left ventricular impairment.