Table 2.

Association of RTR and healthy kidney donors grouping with N¹-MN excretion ¹.

Variable	Model 1 2		Model 2 3		Model 3 4		Model 4 5
	Std.β	p-Value	Std.β	p-Value	Std.β	p-Value	Std.β	p-Value
Grouping	−0.42	<0.001	−0.44	<0.001	−0.25	<0.001	−0.21	<0.001
Sex	-	-	−0.15	<0.001	−0.14	<0.001	−0.10	0.002
Age, years	-	-	−0.16	<0.001	−0.11	<0.001	−0.07	0.02
eGFR, ml/min/1.73 m2	-	-	-	-	0.31	<0.001	0.29	<0.001
Energy intake, kcal/day	-	-	-	-	-	-	−0.10	0.08
Tryptophan intake, mg/day	-	-	-	-	-	-	0.007	0.91
Niacin intake, mg/day	-	-	-	-	-	-	0.25	<0.001
Plasma vitamin B6, nmol/L	-	-	-	-	-	-	0.23	<0.001
R2	0.18		0.23		0.28		0.37

¹ Linear regression analyses were performed to investigate the association of RTR and healthy kidney donors as grouping variable with N¹-MN excretion, with adjustment for potential confounders. ² Model 1: crude model. ³ Model 2: adjusted for age and sex. ⁴ Model 3: adjusted as for model 2 and for eGFR. ⁵ Model 4: adjusted as for model 3 and for intake of energy, tryptophan and niacin and plasma vitamin B₆. eGFR, estimated glomerular filtration rate; N¹-MN, N¹-methylnicotinamide; RTR, renal transplant recipients; std.β, standardized beta coefficient.