Transcript Managing Warfarin Drug Interaction: The Bayview Experience

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
Where is Maryland?
USA
The capital of the state
Where is Baltimore?
Salisbury is REALLY the
cultural epicenter of the state!
Where in Baltimore is Bayview?
Bayview Overview
• Community Teaching Hospital
• Member Institution of Johns Hopkins
Healthcare
• 692 beds
– 320 acute care
– 255 long term/geriatric
– 117 rehabilitation/transitional care
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
JHBMC Patient Breakdown by Diagnosis
JHBMC Patient Breakdown
by Diagnosis
21%
Atrial fibrillation
33%
Prosthetic Heart
Valves
DVT
10%
Cardiomyopathy
10%
11%
15%
Embolic CVA
Other
-9
Ja 7
nM 98
ay
-9
Se 8
p9
Ja 8
nM 99
ay
-9
Se 9
p9
Ja 9
nM 00
ay
-0
Se 0
p0
Ja 0
nM 01
ay
-0
1
Se
p
Volume
Patient Volume
PATIENT
VOLUME
600
500
400
Patient
Volume
300
200
100
0
Date
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
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 (ADE’s) are associated with cost
of $7000 per event (1997 study finding)
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
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
The final outcome
•
•
•
•
•
Three day admission
4 units PRBC’s transfused
Cost to the health care system of $5000-7000
? Cost in lost productivity, work time, etc.
Could this have been avoided?
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
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
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
Frequency of Potentially Interacting Drugs
Carbamazepine
3%
Erythromycin
3%
NSAID's
3%
Cimetidine
5%
Omeprazole
5%
APAP
3%
Amiodarone
26%
Fluconazole
7%
Metronidazole
8%
Ciprofloxacin
22%
Cotrimoxazole
15%
n=59
Time Course from Therapy Initiation to Notification of
Anticoagulation Service
>7 days after 1st
Prior to treatment dose
3% 3-7 days after 1st
8%
dose
23%
Prior to first dose
34%
1-3 days after 1st
dose
32%
n=59
Type of Intervention
None
(18 %)
Alternative Therapy
(10 %)
Dose Alteration
(43 %)
Repeat PT within 72
hrs (58 %)
n=59
Results
Additional Pt
27 % of patients
Therapeutic
50 % of patients
Supratherapeutic
27 % of patients
Subtherapeutic
20 % of patients
n=59
Results
Frequency of Interacting
Therapy
59 cases (23.5 events/100
patient years)
Frequency of Potentially
Interacting Drugs (n)
Amiodarone (n=15);
Ciprofloxacin (n=13);
Cotrimoxazole (n=9)
Prior to treatment (n=5); Prior to
First Dose (n=20); 1-3 Days
after First Dose (n=19); 3-7
Days after First Dose (n=14); >
7 Days after First Dose (n=1)
Alternative therapy (n=6); Dose
Alteration (n= 25); No dose
change (n=18); Additional pT
monitoring (n=34)
Within therapeutic range (n=31);
Subtherapeutic (n=12);
Supratherapeutic (n=16)
Bleeding (n=4)
Time Course from Therapy
Initiation to ACS Notification
(n)
Type of Intervention from
Service (Interventions are
additive)
Effect on Prothrombin Time
(INR)
Adverse Clinical Outcomes
Clinical Adverse Outcomes
#
Type of Adverse
Event
1 Bleeding
Time Frame in
which ACS was
informed
st
>7d after 1 dose
2 Bleeding
3-7d after 1 dose
3 Bleeding
3-7d after 1 dose
4 Bleeding
3-7d after 1 dose
st
st
st
Clinical Sequellae
Gross hematuria
which resolved with
p.o. vitamin K
Inpatient admission
for treatment of INR
and CHF
exacerbation
24 hr ED visit for
observation and
vitamin K
Prolonged inpatient
admission; multiple
transfusions
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 INR’s, 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.
Added Benefits
• Problem:
– JHBMC was showing $6M in laboratory fees
not retrieved
• Solution:
– modify DAWN AC database to create link
between patient demographics
Net Result
• Created a centralized database for billing
department
• Created a template for other clinical services
• Able to retrieve $1.8M of $6M deficit
What else?
• Induction regimen function to facilitate
ambulatory DVT treatment
• Report writing capabilities
• Database management/query abilities
• Screens for monitoring/preventing adverse
drug outcomes
The Bayview Experience
• Facilitated expansion from 285 to 625 patients
• Facilitated ability to capture workflow
fluctuations
• Facilitated ability to capture clinical
interventions
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
Questions, comments, concerns?
E-mail: [email protected]