Table 2. Bootstrapped linear regression.

Determinant	ba,b [CI]	SEba	Beta	t	p	R2
Entire sample
age	0.771 [0.631 - 0.919]	0.073	0.513	10.525	<0.001	0.495
eGFR	-0.223 [-0.355 - (-0.1)]	0.060	-0.207	-4.033	<0.001
HDL	0.049 [-0.029 - 0.127]	0.040	0.061	1.358	0.175
BMI	-0.559 [-0.841 - (-0.294)]	0.144	-0.165	-3.441	0.001
urea	0.164 [0.005 - 0.322]	0.081	0.113	2.362	0.019
blood volume	-0.104 [-1.943 - 1.832]	0.939	-0.005	-0.104	0.918
<60 years
BMI	-0.413 [-0.719 - (-0.144)]	0.147	-0.298	-2.519	0.013	0.17
blood volume	-0.478 [-2.21 - 1.206]	0.865	-0.065	-0.527	0.600
eGFR	-0.084 [-0.184 - 0.017]	0.050	-0.149	-1.546	0.126
age	0.182 [-0.07 - 0.462]	0.128	0.123	1.230	0.222
≥60 years
age	1.24 [0.868 - 1.632]	0.192	0.394	7.089	<0.001	0.379
creatinine	25.183 [13.912 - 35.866]	6.088	0.376	5.041	<0.001
HDL	0.118 [0.01 - 0.215]	0.052	0.149	2.510	0.013
BMI	-0.256 [-0.643 - 0.112]	0.195	-0.077	-1.163	0.246
urea	0.072 [-0.12 - 0.275]	0.097	0.055	0.782	0.435
blood volume	-4.092 [-6.797 - (-1.048)]	1.418	-0.198	-2.671	0.008

^aconfidence interval and standard error with BCa-Bootstrapping with 10.000 BCa-samples.

^bconfidence intervals were used to obtain significance.

Regression coefficients, confidence intervals and standard errors are from bootstrapping. Note: variables violating multicollinearity (i.e. eGFR and creatinine) leaded to the exclusion of the variable with higher variance inflation factor.