Incorporation of a vancomycin nomogram into a standard vancomycin dosing protocol at a community hospital: effect on vancomycin troughs and nephrotoxicity

Introduction:

Pharmacists are consulted to dose greater than 90% of vancomycin orders at our institution.   Our current practice requires pharmacists to select initial vancomycin doses using time-consuming population-based pharmacokinetic equations. An equally efficacious but streamlined method of dosing vancomycin was desired.  Nomograms have been studied as an alternative dosing method for initial regimens. We selected and modified an existing, validated nomogram to fit our current dosing practices.

Objectives:

Our primary objective was to evaluate the rate of goal trough achievement before and after incorporation of the nomogram. Our secondary objective was to evaluate for any change in nephrotoxicity rates.

Study Design:

This is a retrospective cohort study which evaluated 150 patient charts prior to, and after incorporation of a vancomycin nomogram (n = 300).

Methods:

The electronic medical record was reviewed to identify patients who received vancomycin therapy and had at least one vancomycin trough level drawn. Exclusion criteria were patients with a diagnosis of cystic fibrosis, a baseline creatinine clearance below 30 mL/min, or age less than 18 years. Data collection for both pre- and post-implementation  included indication for vancomycin, trough level(s), therapy duration, baseline and serial serum creatinine, and exposure to concomitant nephrotoxins.

Results:

Pre-nomogram data suggested that initial vancomycin goal trough achievement rates were approximately 31% at our institution, with an additional 11% of patients falling within 1 mcg/mL of the goal range. The incidence of nephrotoxicity for patients receiving vancomycin without concomitant nephrotoxins was 4.5%, which is similar to the 5-7% rate described in previous studies.

Conclusions:

No conclusions have been made at this time, as our research is still in progress.