Gap Analysis for the Conversion to Area Under the Curve Vancomycin Monitoring in a Small Rural Hospital

Results

The transition was effective with 97% of all cases utilizing AUC-based methods for monitoring. A total of 65 vancomycin levels were drawn in the study period; 32 peaks, 32 troughs, and 1 random level (drawn appropriately during acute renal failure 24 hours after starting therapy). All shifts were affected proportionately; days (n = 26, 40%), nights (n = 18, 27.7%), and weekends (n = 21, 32.3%). Based on time of dosage administration and laboratory test, there were 9 levels (13.8%) deemed inappropriate, 56 levels (86.1%) were appropriate. Reasons for inappropriate levels gleaned from chart review are presented in Table 2. Four levels had to be repeated for accurate calculations.

From the peak/trough couplets drawn appropriately, calculated AUC₂₄ fell with the desired range in 61% (n = 17) of cases. Of the 11 that fell outside of range, 8 were subtherapeutic (< 400 mg.h/L) and 3 were supratherapeutic (> 600 mg.h/L). All levels were drawn at steady state. Indications for vancomycin monitoring were osteomyelitis (n = 13, 43%), sepsis (n = 10, 33%), pneumonia (n = 6, 20%), and 1 case of meningitis (3%).

Discussion

To the author’s knowledge, this is the first report of a vancomycin AUC₂₄ monitoring conversion in a rural facility. This study adds to the existing medical literature in that it demonstrates that: (1) implementation methods described in large, tertiary centers can be effectively utilized in primary care, rural facilities; (2) the gap analysis used can be duplicated with minimal personnel and resources to ensure effective implementation (Table 3); and (3) the reported improvement needs can serve as a model for preventative measures at other facilities. The incidence of appropriate vancomycin levels was notably better than those reported in other single center studies.^15-17 However, given variations in study design and facility operating procedures, it would be difficult to compare incidence among medical facilities. As such, there are no consensus benchmarks for comparison. The majority of inappropriate levels occurred early in the study period and on weekends. Appropriateness of drug levels may have improved with continued feedback and familiarity.

The calculated AUC₂₄ fell within predicted range in 61% of cases. For comparison, a recent study from a large academic medical center reported that 73.5% of 2-level AUC₂₄ cases had initial values within the therapeutic range.¹⁸ Of note, the target range used was much wider (400 - 800 mg.h/L) than the present study. Another study reported dose adjustments for subtherapeutic AUC levels in 25% of cases and dose reductions for supratherapeutic levels in 33.3% of cases.¹⁹

Of the AUC₂₄ calculations that fell outside of therapeutic range, the majority (n = 8, 73%) were subtherapeutic (< 400 mg.h/L), half of these were for patients who were obese. It was unclear in the medical record which equation was used for initial dosing (Matzke vs Crass), or whether more conservative AUCs were used for calculating the total daily dose. The VHSO policy limiting loading doses also may have played a role; indeed the updated guidelines recommend a maximum loading dose of 3,000 mg depending on the severity of infection.⁴ Two of the 3 supratherapeutic levels were thought to be due to accumulation with long-term therapy.

Given such a large change from long-standing practices, there was surprisingly little resistance from the various clinical services. A recent survey of academic medical centers reported that the majority (88%) of all respondents who did not currently utilize AUC₂₄ monitoring did not plan on making this immediate transition, largely citing unfamiliarity and training requirements.²⁰ It is conceivable that the transition to AUC monitoring in smaller facilities may have fewer barriers than those seen in tertiary care centers. There are fewer health care providers and pharmacists to educate with the primary responsibilities falling on relatively few clinicians. There is little question as to who will be conducting follow up or whom to contact for questions. A smaller patient load and lesser patient acuity may translate to fewer vancomycin cases that require monitoring.

The interactive meetings were an important element for facility implementation. Research shows that emails alone are not effective for health care provider education, and interactive methods are recommended over passive methods.^21,22 Assessing and avoiding barriers up front such as unclear laboratory orders, or communication failures is paramount to successful implementation strategies.²³ Additionally, the detailed written ordering communication may have contributed to a smoother transition. The educational recording proved to be helpful in educating new staff and residents. An identified logistical error was that laboratory orders entered while patients were enrolled in sham clinics for electronic workload capture (eg, Pharmacy Inpatient Clinic) created confusion on the physical location of the patient for the phlebotomists, potentially causing delays in specimen collection.

A major development that stemmed from this intervention was that the Medical Service asked that policy changes be made so that the Pharmacy Service take over all vancomycin dosing at the facility. Previously, this had been done on a collaborative basis. Similar facilities with a collaborative practice model may need to anticipate such a request as this may present a new set of challenges. Accordingly, the pharmacy department is in the process of establishing standing operating procedures, pharmacist competencies, and a facility memorandum. Future research should evaluate the safety and efficacy of vancomycin therapy after the switch to AUC-based monitoring.