New study details devastating impact of HHV-6 encephalitis

Investigators in Japan studied 145 HHV-6 encephalitis patients and found that at 100 days after transplantation, the overall survival rate was just 58.3%, compared with 80.5% of HSCT transplant patients who did not develop HHV-6 encephalitis (P<0.001)), and neuropsychological sequelae remained in 57% of these patients.

The data comes from 6500 transplant patients. The cumulative incidence of HHV-6 encephalitis at 100 days after transplantation was 2.3% in all patients (5.0% among recipients of cord blood and 1.6% among recipients of bone marrow or PBSCs).

Risk factors for the development of HHV-6 encephalitis identified in multivariate analysis were: type of transplanted cells (relative risk in cord blood transplantation, 11.09, P<0.001), HLA-mismatched unrelated donor (relative risk in transplantation from HLA-mismatched unrelated donor vs. HLA-matched related donor, 9.48, P<0.001), male sex, and use of GVHD prophylaxis by calcineurin inhibitor alone.

The authors also note that full-dose antiviral therapy (foscarnet >180 mg/kg, ganciclovir >10 mg/kg) was associated with better response rate (foscarnet, 93% vs 74%, P = 0.044; ganciclovir, 84% vs 58%, P = 0.047).

The authors caution that the effect of HHV-6 encephalitis on survival is substantial in transplant patients, and that the condition occurs not uncommonly among recipients of both cord blood and HLA-mismatched unrelated donor. Beyond the substantial effect on survival, a majority of these patients experienced significant and lasting neuropsychological sequelae.

For more information, read the full article: Ogata 2017