Table 1.

United States donor-derived cell-free DNA levels in kidney transplant recipients

US samples	> 1%	0.5% to 1%	< 0.5%
No. weeks	21	21	21
Mean no. samples	94.9 (11.9%)	119.7 (15.0%)	584.3 (73.1%)
SD	21.4	30.0	129.2
Regression slope	-0.31	-0.12	+0.08
K-S	0.16	0.17	0.12

United States donor-derived, cell-free DNA weekly grouped samples categorized as cohorts. Linear regression slopes (samples/week) for individual cohort numbers of samples versus time. Normality was assessed with Kolmogorov-Smirnov (K-S) (P < 0.05), and all 3 cohorts were normally distributed.

SD, standard deviation; US, United States.