Predictive factors of spontaneous CMV DNAemia clearance in kidney transplantation

Cytomegalovirus (CMV) infection occurs frequently after solid organ transplantation. Therapeutic strategies, in particular when to start a curative treatment, has not yet been defined. The purpose of this study was to assess predictive factors associated with spontaneous clearance of CMV DNAemia in kidney transplant recipients.

All kidney recipients of a single center were recruited. Patients with at least one positive CMV DNAemia during the first year post transplantation were included in our analysis. Whole blood CMV PCR was performed using Abbott^® RealTime CMV, calibrated according to WHO standards and expressed in log10 IU/ml (Detection = 1.79 IU log10/ml). Post transplantation, prophylaxis (valganciclovir) was given for 3 months for CMV positive recipients (R+) and 6 months for CMV positive donors giving to seronegative recipients (D + R-). Clinical and biological symptoms attributable to CMV were collected. We defined as spontaneous CMV clearance undetectable DNAemia before the fourth follow up without treatment. Results were expressed as mean ± SD. Results were prospectively assessed in a French multicenter validation cohort.

Between 05/2012 and 05/2015, 95 patients had at least one positive CMV DNAemia. Thirty-six (37.8%) had spontaneous undetectable DNAemia. Fifty-nine patients had non-spontaneous CMV clearance. ROC analysis showed that an initial CMV DNAemia <2.75 log10/IU/mL was optimal to predict CMV spontaneous clearance. On multivariate analysis, factors associated with spontaneous CMV clearance were initial PCR level lower than 2.75 log10/IU/ml (OR = 33.8, 95% CI [7.1-160.0]), and absence of CMV DNAemia increase of more than 1 log10 between two analyses (OR = 128.0, 95% CI [11.9-1368.0]). Clinical and biological abnormalities were not associated CMV DNAemia spontaneous clearance. Observations made for the principal cohort were validated in an independent cohort of 49 kidney transplanted patients.

Initial standardized CMV DNAemia level and evolution of DNAemia are the principal factors associated with CMV spontaneous clearance.