Table 1.

Characteristics of the study population according to reactivity with different bead preparations (n = 837).

Class I DSA (no. patients)	Bead type
	Regular SAB	iBeads	Denatured SAB
	Pos	Pos/Neg	Pos/Neg
	156	120/36	64/92
Recipient sex (no. male)	68	48/20	25/43
(no. female)	88	72/16*	39/49
Recipient age (years ± s.d.)	46 ± 13	47 ± 14/45 ± 13	46 ± 14/47 ± 13
Donor sex (no. male)	77	58/19	36/41
(no. female)	79	62/17	28/51
Donor age (years ± s.d.)	45 ± 15	45 ± 14/44 ± 16	46 ± 14/44 ± 15
Transplant type
no. living	31	23/8	13/18
no. deceased	125	97/28	51/74
Transplant (no. = 1)	130	97/33	55/75
(no. > 1)	26	23/3	9/17
Cold ischaemia time (h ± s.d.)	19 ± 12	19 ± 12/20 ± 12	20 ± 13/18 ± 12
HLA-A,-B-DR mismatches (no.)
0	6	3/3	2/4
1–4	144	112/32	57/87
5–6	6	5/1	5/1
Induction therapy applied	21	15/6	7/14
not applied	135	105/30	57/78
hPRA < 5	74	50/24**	29/45
≥ 5	82	70/12	35/47

Patients were defined as single antigen bead-donor-specific human leucocyte antigen (HLA) antibodies (SAB-DSA)-positive when mean fluorescence intensity (MFI)-values of HLA antibodies against kidney grafts were 1000 above background values. The sera from 156 patients with HLA class I DSA defined by regular SAB were analysed further using iBeads and beads with denatured HLA. Maintenance immunosuppression was applied as indicated in the Patients and methods section, with a change in 1997. Interleukin (IL)-2 blockade as induction therapy has been applied since 2005 in patients with an established high immunological risk (i.e. second or more kidney transplantation or panel reactive antigen > 40%). hPRA, highest historical pretransplant value of panel-reactive antibodies; s.d.: standard deviation. Asterisks indicate the following P-values

^*P = 0·07

^**P = 0·007.