Purpose: Renal function rapidly changes post-transplant requiring dose adjustment of CMV prophylaxis. We describe valganciclovir (VGCV) dosing accuracy in the outpatient setting and its associated safety and efficacy.

Methods: The retrospective cohort included adult kidney recipients at Cleveland Clinic transplanted October 2015-May 2017 and discharged on renally adjusted VGCV. Data were collected at discharge, the first 4 post-transplant outpatient visits (POVs), and through the CMV prophylaxis period.

Results: Of 219 subjects screened, 103 met inclusion which represented 299 unique POVs. At 59% of POVs, VGCV dose was either already correct for renal function or correctly adjusted if indicated. At the remaining 41% of POVs, VGCV was either non- or incorrectly adjusted for renal function (55% underdosed; 41% overdosed). Those whose VGCV dose was correct through POV 4 were defined as Dose Optimized (DO) (n=43); the remaining (n=60) were designated Not Dose Optimized (NDO). The majority received a deceased organ, anti-thymocyte globulin induction, and were discharged on tacrolimus, prednisone, and 1500 mg/day mycophenolate (p>0.05 for all variables). CMV serostatus distribution was similar between groups. The NDO group had a lower CrCl (26 vs. 37 mL/min, p=0.02) and were more frequently discharged on a lower VGCV dose (80% vs. 56%, p<0.01) compared to the DO group. There was no significant difference in white blood cell count between groups at POV 1, POV 4, and end of prophylaxis. The number of absolute neutrophil count occurrences <500 k/uL was also similar through POV 4 and end of prophylaxis. There were 4 episodes of breakthrough CMV viremia, 2 per group. The two DO group episodes resulted in viremia that was detectable but unquantifiable (< 137 IU/mL). Both NDO group episodes occurred in CMV high-risk (D+/R-) subjects. The first subject's VGCV dose was low and not optimized during POV 2 resulting in CMV viremia of 307 copies/mL within 6 days. The second subject's VGCV dose was low and not optimized during POVs 2-4, and CMV viremia was 151642 IU/mL 49 days later. The subject experienced CMV colitis and required hospitalization.

Conclusions: Despite no observed safety concerns and few CMV events, opportunity exists for improved VGCV dose-optimization in the outpatient setting. This could further reduce or eliminate CMV viremia and associated morbidities, with particular focus on CMV high-risk patients with changing renal function.

CITATION INFORMATION: Spinner M., Athans V., Koval C. Outpatient Prophylactic Valganciclovir Dose Optimization Post-Renal Transplant Am J Transplant. 2017;17 (suppl 3).

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