Outcomes of renal transplant recipients with BK virus infection and BK virus surveillance in the Auckland region from 2006 to 2012

Table 1 Demographics and clinical characteristics of renal transplant recipients with/without BK polyomavirus nephropathy and comparison between those with BK polyomavirus nephropathy and BK viraemia n (%)

	(-) BKVN (n = 217)	(+) BKVN (n = 9)	P value	(+) BKV (n = 19)	P value
Age (yr)	48 (35.3-56.8)	55 (34.9-60.5)	NS	50 (27.1-60)	NS
Gender (female)	92 (42.3)	3 (33.3)	NS	6 (31.6)	NS
Ethnicity
European	131 (98.5)	2 (1.5)	0.038	11 (57.9)	0.191
Asian	32 (90.7)	3 (9.3)		4 (21.1)
Māori and Pacific Islander	54 (92.6)	4 (7.4)		4 (21.1)
Cause of ESKF
Glomerulonephritis	91 (41.9)	5 (55.6)	NS	8 (42.1)	NS
Diabetes mellitus	26 (12.0)	2 (22.2)		2 (10.5)
Others	55 (46.1)	2 (22.2)		9 (47.4)
Co-morbidity
Diabetes mellitus	26 (11.9)	2 (22.2)	NS	2 (10.5)	NS
Hypertension	130 (59.9)	5 (55.5)	NS	12 (63.2)	NS
Cardiac disease	31 (14.2)	2 (22.2)	NS	3 (15.8)	NS
Dialysis vintage (yr)	2 (0.2-5)	5 (1-6)	NS	2.5 (0-5)	NS
Donor source (deceased)	118 (54.3)	9 (100)	0.005	9 (47.4)	0.01
HLA mismatch	3 (2-4)	4 (2.5-4)	NS	3.5 (2-5)	NS
Basiliximab induction	95 (43.7)	3 (33.3)	NS	13 (68.4)	NS
Tacrolimus	92 (42.3)	5 (55.6)	NS	10 (52.6)	NS
Cold ischaemia time (h)	7 (4-15)	19 (14.2-20.4)	0.001	5.4 (4-12.5)	< 0.0001
AR at any time point
0 episode	144 (66.4)	3 (33.3)	0.069	9 (47.4)	NS
≥ 1 episode(s)	73 (33.6%)	6 (66.7)		10 (52.6)
AR before known BKV/BKVN status
10 → 0 episode	-	3 (33.3)		10 (52.6)	NS
11 →≥ 1 episode(s)	-	6 (66.7)		9 (47.6)
Thymoglobulin for acute rejection	33 (15.2)	0 (0)	NS	5 (26.3)	NS

Values are expressed as numbers (percentages) and medians (interquartile range Q1-Q3). P value are calculated using non-parametric test and Fisher’s exact test, and actual values are shown if P < 0.1. BKVN: BK polyomavirus nephropathy; (+) BKV: Recipients with BK viraemia without biopsy-proven BKV nephropathy; NS: Not significant; AR: Acute rejection; ESKF: End-stage kidney failure; HLA: Human leukocyte antigen.

Table 2 Univariable and multivariable Cox regression to assess potential risk factors for BK polyomavirus nephropathy

	Crude HR (+) BKVN	95%CI	P value	Adjusted HR (+) BKVN	95%CI	P value
Gender (female)	0.66	0.16-2.66	NS
Ethnicity (reference: European)
Asian	6.36	1.06-38.16	0.043	3.731	0.61-22.92	0.154
Māori/Pacific Islander	4.75	0.87-25.94	0.072	2.631	0.45-15.25	0.279
Co-morbidity
Diabetes mellitus	2.06	0.42-9.94	NS
Basiliximab induction	0.75	0.18-3.03	NS
Tacrolimus	1.64	0.44-6.11	NS
Thymoglobulin for rejection	0.03	0.00-88.65	NS
Cold ischaemia time	1.18	1.06-1.32	0.003	1.181	1.04-1.35	0.009
Acute rejection (≥ 1 episode)2	3.72	0.93-14.91	0.063	4.051	0.99-16.53	0.051
HLA mismatch	1.15	0.75-1.77	NS

¹Variables included in the multivariable Cox regression model;

²Acute rejection at any time point. HR: Hazard ratio; CI: Confidence interval; (+) BKVN: BK polyomavirus nephropathy nephropathy; HLA: Human leukocyte antigen; NS: No significance.

Table 3 Clinical outcome of the renal transplant recipients with BK polyomavirus nephropathy after a reduction of immunosuppressive therapy

Recipients with BKVN	BKVL at diagnosis	eGFR at 1 mo	eGFR at CD	BKVL outcome1	Time to outcome1	Acute rejection (post reduction of IS)
1	1100000	48.7	73	Undetectable	28 mo	No
2	3250	17.8	22	Undetectable	44 mo	Yes (at 30 mo)
3	364700	36.9	23	Undetectable	31 mo	Yes (at 2 mo)
4	265650	21.5	59	Undetectable	17 mo	No
5	47225	23	18	< 625	7 mo	No
6	1794502	57	35	3725	59 mo	No
7	59736502,3	33.4	20	41175	12 mo	No
8	295608752,3,4	50.2	16	30425	8 mo	No
9	56125	27.9	Graft failure	Graft failure	21 mo	No

¹Follow-up censored at December 2013;

²Use of Leflunomide;

³Use of Ciprofloxacin;

⁴Use of intravenous Immunoglobulin. BKVL: BK viral load (copies/mL); BKVN: BKV Nephropathy; IS: Immunosuppressant; CD: Censored date; eGFR: Estimated glomerular filtration rate (mL/min per 1.73 m²).