I would appreciate the expert opinion on current CMV prophylaxis strategies in SOT. In particular, I would like to know what does he think about low-dose valganciclovir (450 mg/day) vs. full-dose (900 mg/day). What's the trend in terms of dosage in most US Transplant Centers nowdays (for example, Kidney Tranplant programs)? What about universal vs. only high-risk recipients prophylaxis? If a Kidney Transplant program does experience a very high rate of significant leukopenia implementing 900 mg/day as standard CMV prophylaxis (3-month course), should it be the next step switching to low-dose valganciclovir?
No randomized studies directly comparing 450mg and 900mg of valganciclovir exist to the best of my knowledge. However, there is data supporting the efficacy of both doses which suggests that the lower dose is probably sufficient in most situations. At our institution, we provide 900mg only to our D+R- liver transplant recipients. All other liver and kidney recipients (except D-R-) receive 450 mg (or adjusted for renal function). Clinicians should be aware of two issues. First, late-onset CMV disease after prophlyaxis has been discontinued is a signficant problem in D+R- patients. Second, dosing of valganciclovir should be readjusted in renal transplant recipients with fluctuating renal function. Most importantly, as renal function improves the dose should be increased to avoid suboptimal prophylaxis and breakthrough CMV disease. Leukopenia can be addressed by either decreasing the dose or providing GCSF.