title: Cytomegalovirus load at treatment initiation is predictive of time to resolution of viremia and duration of therapy in hematopoietic cell transplant recipients.
abstract: BACKGROUND
  Preemptive antiviral therapy relies on viral load measurements and is the mainstay of cytomegalovirus (CMV) prevention in hematopoietic cell transplant (HCT) recipients. However, optimal CMV levels for the initiation of preemptive therapy have not been defined.
  
  
  OBJECTIVE
  The objectives of our work were to evaluate the relationship between plasma CMV DNA levels at initiation of preemptive therapy with time to resolution of viremia and duration of treatment.
  
  
  METHODS
  Retrospective analysis of HCT recipients undergoing serial CMV PCR testing between June 2011 and June 2014 was performed.
  
  
  RESULTS
  221 HCT recipients underwent preemptive therapy for 305 episodes of CMV viremia. Median time to resolution was shorter when treatment was initiated at lower CMV levels (15 days at 135-440 international units (IU)/mL, 18 days at 441-1000 IU/mL, and 21 days at >1000 IU/mL, P<.001). Prolonged viremia lasting >30 days occurred less frequently when treatment was initiated at 135-440 IU/mL compared to 441-1000 IU/mL and >1000 IU/mL (1%, 15%, 24%, P<.001). Median treatment duration was also shorter in the lower viral load groups (28, 34, 37 days, P<.001).
  
  
  CONCLUSIONS
  Initiation of preemptive therapy at low CMV levels was associated with shorter episodes of viremia and courses of antiviral therapy. These data support the utility of initiating preemptive CMV therapy at viral loads as low as 135 IU/mL in HCT recipients.
authors.affiliation: Department of Medicine, Division of Infectious Diseases and Geographic Medicine, Stanford University School of Medicine, Stanford, CA, USA.
authors.forename: Susanna K
authors.initials: SK
authors.lastname: Tan
authors.affiliation: Department of Medicine, Division of Infectious Diseases and Geographic Medicine, Stanford University School of Medicine, Stanford, CA, USA.
authors.forename: Jesse J
authors.initials: JJ
authors.lastname: Waggoner
authors.affiliation: Department of Medicine, Division of Infectious Diseases and Geographic Medicine, Stanford University School of Medicine, Stanford, CA, USA; Department of Pathology, Stanford University School of Medicine, Stanford, CA, USA. Electronic address: bpinsky@stanford.edu.
authors.forename: Benjamin A
authors.initials: BA
authors.lastname: Pinsky
mesh_terms: D000328:Adult; D000998:Antiviral Agents / Q000627:therapeutic use; D003587:Cytomegalovirus / Q000187:drug effects / Q000235:genetics* / Q000502:physiology; D003586:Cytomegalovirus Infections / Q000097:blood / Q000517:prevention & control*; D004279:DNA, Viral / Q000097:blood* / Q000187:drug effects; D018380:Hematopoietic Stem Cell Transplantation; D006801:Humans; D008875:Middle Aged; D012189:Retrospective Studies; D013997:Time Factors; D066027:Transplant Recipients; D016896:Treatment Outcome; D019562:Viral Load / Q000187:drug effects; D014766:Viremia / Q000517:prevention & control*
chemical_list: D000998:Antiviral Agents; D004279:DNA, Viral
keywords: Cytomegalovirus; Hematopoietic cell transplantation; Pre-emptive therapy; Quantitative real-time polymerase chain reaction; Viral load; WHO International Standard