Table 1.

Baseline characteristics of healthy nondonors and living kidney donors before and after weighting

Characteristic	Healthy Nondonors	Kidney Donors	Standardized Bias
Unweighted study population
N	8233	1295
Baseline age, median yr (IQR)	49 (40–55)	46 (38–53)
Men, %	46	36
Black, %	24	14
Baseline BMI, median (IQR)	26 (23–28)	26 (24–30)
Missing baseline BMI, %	0	35
Baseline eGFR, median (IQR)	93 (83–103)	96 (83–107)
Missing baseline eGFR, %	0	22
High school education, %
Yes	88	94
No	12	1
Missing	0	5
Some college education, %
Yes	59	64
No	41	32
Missing	0	5
Ever smoker, %
Yes	52	36
No	38	59
Missing	10	5
Weighted study population
N	935	1295
Baseline age, mean yr ±SD	45±10	45±11	0.04
Men, %	37	36	0.02
Black, %	11	14	−0.09
Obese, %	15	23	−0.18
Baseline eGFR, mean ml/min ±SD	95±14	96±17	−0.06
High school education, %	98	99	−0.02
Some college education, %	68	67	0.01
Ever smoker, %	40	38	0.03

Unweighted healthy nondonors are compared with donors using Wilcoxon signed-rank sum tests and chi-squared tests, whereas weighted healthy nondonors are compared with donors using standardized bias. Balance through weighting is demonstrated by all baseline characteristics having a standardized bias <0.25 (17). IQR, interquartile range; BMI, body mass index.