Transient versus persistent BK viremia and long-term outcomes after kidney and kidney-pancreas transplantation

Abstract

Background and objectives: The objective was to study the long-term impact of transient versus persistent BK viremia on kidney transplant outcomes.

Design, setting, participants, & measurements: In total, 609 recipients who underwent kidney transplant from 2007 to 2011 were screened at months 1-12 for the occurrence of polyomavirus BK viremia; 130 patients (21.7%) developed BK viremia during the first year post-transplant. BK viremia patients were classified according to duration of infection (more or less than 3 months), and BK viral loads (more or less than 10,000 copies/ml) were classified as transient low viremia (n=42), transient high viremia (n=18), persistent low viremia (n=23), and persistent high viremia (n=47). All patients were followed a median of 36 (3-66) months. The rates of BK polyomavirus-associated nephropathy, acute rejection, and 1-year graft function were compared with the polyomavirus BK-negative control group.

Results: Patient and graft survival were not significantly different among the groups. Graft function (creatinine; milligrams per deciliter) at 1 year was significantly worse in the persistent high viremia (1.75±0.6) and transient high viremia (1.85±0.7) groups compared with aviremic controls (1.47±0.4; P=0.01 and P=0.01, respectively). The incidence of BK polyomavirus-associated nephropathy was limited to the persistent high viremia group (1.3%, P<0.001). The transient high viremia (50%) and persistent high viremia (34%) groups showed significantly (P=0.01) increased incidence of acute rejection versus aviremic controls (21.5%), transient low viremia (19%), or persistent low viremia (17.3%) groups.

Conclusion: Low viral load BK viremia, either transient or persistent, was not associated with long-term transplant outcomes. Persistent high viremia was associated with a greater risk for BK polyomavirus-associated nephropathy and subsequent graft dysfunction. Although transient high viremia was not associated with BK polyomavirus-associated nephropathy, it was associated with worse graft function. These data support the role of surveillance for BK viremia after transplant.

Figure 1.

Patient survival by Kaplan‐Meier analysis in the selected study population. (A) Overall, patient survival was 95.2% at a median follow-up of 36 (range=3–66) months, which was not significantly different for the five groups stratified by BK viremia persistence and viral loads (log-rank P=0.10). (B) Graft survival by Kaplan–Meier analysis in the selected study population. Overall, patient survival was 92.6% at a median follow-up of 36 (range=3–66) months, which was not significantly different for the five groups stratified by BK viremia persistence and viral loads (log rank P=0.60).

Figure 2.

Graft rejection by Kaplan–Meier analysis. There is a significant difference in the long-term graft rejection rates among the five groups (21.5% rejection in negative polyomavirus BK [BKV] infection, 17.3% rejection in persistent low viremia, 19% rejection in transient low viremia, 34% rejection in persistent high viremia, and 50% rejection in transient high viremia; log-rank P=0.01).