1053. Identification of Clinical Factors for Performing Voriconazole (VRC) Therapeutic Drug Monitoring (TDM) at an Academic Medical Center
Session: Poster Abstract Session: Stewardship: Improving Treatments
Friday, October 4, 2013
Room: The Moscone Center: Poster Hall C
Background: VRC TDM with dose adjustments based on trough serum concentrations (SC) became common practice at our institution in 2010. However, it was performed by clinician discretion; interpretation of SC and modifications to VRC therapy were variable.  We aimed to determine clinical factors associated with performing VRC TDM and to characterize SC obtained.

Methods: All patients receiving VRC between 5/1/10 and 1/30/12 were retrospectively reviewed.  Prophylactic VRC indications were excluded. Patient, laboratory, and drug administration data were collected. Patients receiving TDM were compared to those not receiving TDM.

Results: 86 patients receiving VRC for treatment indications were evaluated, 42 received TDM. Hematologic malignancy (78.6% vs. 54.5%; p=0.018), history of invasive mold infection (19% vs. 6.8%; p=0.09), neutropenia (66% vs. 47.8%; p=0.09), and combination antifungal (AF) therapy (10.5% vs. 0%; p=0.027) were more common in the TDM group. Median duration of inpatient VRC therapy was 8.5 days in the TDM group and 4 days in the non-TDM group (p<0.001). Combination AF therapy (p=0.03) and duration of inpatient VRC (p=0.002) were independently associated with performing TDM on multivariate analysis. Indications for TDM, determined for 91% of SC, were as follows: Routine monitoring (after ≥5 days of therapy) (79%), toxicity (6%), repeating inappropriate SC (3%), concern for efficacy (1.5%), and 30-day follow-up of prior SC (1.5%). A total of 66 VRC SC were evaluated: 54 (82%) inpatient and 12 (18%) outpatient.  Timing of TDM in relation to the VRC dose was determined for inpatient SC. Of these, 54% were trough values; the median trough value was 3.1 mcg/mL (IQR 1.1-6.4 mcg/mL). Therapeutic troughs (2-5.5 mcg/mL) were obtained in 44% of patients.  Subsequent adjustments to doses or AF therapy were made in 45% of patients with non-trough SC.

Conclusion: VRC TDM is associated with higher acuity patients. Adjustments to therapy were commonly made based on inappropriately drawn SC. Institutions utilizing VRC TDM should establish standardized recommendations for conducting TDM, including timing of SC monitoring and subsequent dose adjustments, to ensure patient safety and clinical efficacy.

Mildred Vicente, PharmD1, Jennifer Pisano, MD2, Sandeep Parsad, PharmD1, Natasha Pettit, PharmD1, Kenneth Pursell, MD2 and Benjamin Brielmaier, PharmD1, (1)Pharmacy Services, The University of Chicago Medicine, Chicago, IL, (2)Infectious Diseases and Global Health, The University of Chicago Medicine, Chicago, IL

Disclosures:

M. Vicente, None

J. Pisano, None

S. Parsad, None

N. Pettit, None

K. Pursell, None

B. Brielmaier, None

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