Prevalence of BK Virus Infection in a Large Heart Transplant Population

Abstract

In heart transplant (HT) patients, prevalence of BK virus (BKV) infection and its clinical significance are unknown. We sought to understand rates of BKV infection in a large HT cohort and to evaluate risk factors and effects of infection. Consecutive HT patients at a single institution were evaluated for BKV infection in blood and urine in the 1st year post-transplant. Titers were collected 1-month post-transplant and then every 6 months, with additional testing if needed. Rates of infection were compared between HT and combined organ transplant. In the HT group, patients with no infection, viruria with no viremia, and viremia with or without viruria were compared. Measures of immunity and kidney function were collected with titers in blood to evaluate Spearman rank correlations using log10 transformation. 104 patients were enrolled: 89 HT, 12 heart/kidney transplant (HKT), 1 heart/liver transplant, 2 heart/liver/kidney transplant. Viruria and viremia were highly prevalent in HT (42% and 30%, respectively). Compared to HT patients without infection, those with viremia were older (57.8 vs 50.8 yrs, p=0.04), and tended to have lower pre-transplant glomerular filtration rate (GFR) (63.3 vs 71.4 mg/dL/1.73m2, p=0.14). There were no significant differences between patients with viruria compared to viremia. 1-year freedom from viruria was 55% in HT vs 46% in HKT. 1-year freedom from viremia was 67% in HT vs 56% in HKT (Figure). Viremia titers in HT strongly correlated with immunoglobulin (IgG) levels (R= -0.60, p=0.001), but not other immunity measures. Viremia titers were not correlated with GFR (R= 0.05, p=0.70). When comparing GFR before transplant to 1-year post-transplant, there was no significant difference found in the groups with no infection, viruria, and viremia (-22.4 vs -23.7 vs -23.4 mg/dL/1.73m2, p=0.98). BK viremia is very common in HT patients. BK viremia correlated with IgG, but not kidney function. Longer surveillance studies are needed to evaluate effects of BKV infection.