Managing Warfarin Drug Interactions: The Bayview Experience

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Managing Warfarin Drug Interactions The Bayview
Experience
Charles H. Twilley, MBA, PharmD Johns Hopkins
Bayview Medical Center Baltimore, MD USA

• DAWN Users Group, November 2002

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Where is Maryland?
USA
The capital of the state
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Where is Baltimore?
Salisbury is REALLY the cultural epicenter of the
state!
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Where in Baltimore is Bayview?
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Bayview Overview

• Community Teaching Hospital
• Member Institution of Johns Hopkins Healthcare
• 692 beds
• 320 acute care
• 255 long term/geriatric
• 117 rehabilitation/transitional care

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The Anticoagulation Service At Bayview

• Clinical Initiative of the Department of Pharmacy
  Services
• Occupies 1 FTE
• Responsible for all aspects of chronic
  anticoagulation management, including acute
  bridge therapy with heparin, outpatient DVT Tx.
• Currently has 625 patients on service up from
  285 in 1998

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JHBMC Patient Breakdown by Diagnosis
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PATIENT VOLUME
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Problems with Anticoagulation Management at
Bayview

• No formalized inpatient management service
• approval slated for November, 2002
• Difference in level of pharmaceutical care
  between acute and long term care
• JHBMC is a teaching facility
• Large geriatric population

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Magnitude of the Problem

• Warfarin associated 22 of adverse drug reactions
  in Q3 FY 2000-2001
• Heparin is associated with 51 of medication
  errors for Q1-Q3 FY 2000-2001
• Problems with anticoagulation management
  implicated in two sentinel events over the past
  16 months
• Adverse Drug Events (ADEs) are associated with
  cost of 7000 per event (1997 study finding)

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Case Study

• CJ 48 y.o. AA male, s/p cadaveric renal
  transplant, developed embolic CVA
• chronically anticoagulated for 4 years
• Presented to PCP with painful, discolored,
  cracking of great toe diagnosed as onychomycosis
• Treated with itraconazole 100mg po qd

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Case Study 14 days later

• Presents to AC clinic
• Pertinent findings
• INR 18.5 (repeated and verified)
• Hgb/Hct 7.5/22
• Guiac
• When asked why
• neither my doctor nor the pharmacist that filled
  the prescription thought it would be a problem

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The final outcome

• Three day admission
• 4 units PRBCs transfused
• Cost to the health care system of 5000-7000
• ? Cost in lost productivity, work time, etc.
• Could this have been avoided?

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What could the ACS do?

• Prevent admissions from outpatients served
• Instill the notion of drug interactions into
  introductory didactic patient education
• Implement specific, evidence-based policies and
  procedures to address management
• Utilize management database to facilitate

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How did the ACS utilize DAWN AC?

• Utilized the drug interactions screen function
• incorporated Drug Interaction algorithm into
  interaction tracking function
• provided prescriber with notification of
  interaction and cited literature

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How did we test our results?

• Identified drug interactions with clinically
  relevant evidence of severity
• chose drug with Evidence Levels I and II of
  clinical significance (Wells, et al.)
• Evaluated efficacy of our ACS to prevent/minimize
  warfarin interactions
• Conducted prospective evaluation from 07/01/99 to
  01/01/2000 to evaluate efficacy

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Results
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Clinical Adverse Outcomes
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Conclusions

• Potential interactions with warfarin occur at a
  rate of 23.5 events/100 patient years
• A defined algorithmic approach can minimize the
  incidence of supratherapeutic INRs, thus
  minimizing adverse clinical events.
• Provider notification and intervention within 72
  hours after a potentially interacting medication
  is started may reduce the risk of major bleeding.
  Patients need to be continually reminded to
  inform their anticoagulation care provider when
  new medications are initiated.

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Added Benefits

• Problem
• JHBMC was showing 6M in laboratory fees not
  retrieved
• Solution
• modify DAWN AC database to create link between
  patient demographics

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Net Result

• Created a centralized database for billing
  department
• Created a template for other clinical services
• Able to retrieve 1.8M of 6M deficit

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What else?

• Induction regimen function to facilitate
  ambulatory DVT treatment
• Report writing capabilities
• Database management/query abilities
• Screens for monitoring/preventing adverse drug
  outcomes

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The Bayview Experience

• Facilitated expansion from 285 to 625 patients
• Facilitated ability to capture workflow
  fluctuations
• Facilitated ability to capture clinical
  interventions

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Future Initiatives

• Use of induction module to undertake inpatient
  ACS
• use of hand held technology to make ACS a
  mobile clinical entity
• further expand outpatient clinical pharmacy
  services
• Lipid management, diabetes management

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Questions, comments, concerns?

• E-mail ctwilley_at_jhmi.edu