Study design. After completion of pharmacokinetic sampling on day 11, all treatment decisions were made based on the results of the Cobas Amplicor CMV MONITOR (CMV-M) assay. Using this assay, responders were defined as patients with CMV DNA less than 400 copies/mL. Nonresponders were defined as patients with CMV DNA at least 400 copies/mL. V-GCV indicates valganciclovir; and IV-GCV, intravenous ganciclovir.