• 5
    Nov
  • Implementation and Evaluation of a Warfarin Dosing Service for Rehabilitation Medicine: Report from a Pilot Project: RESULTS

Hospital Administrators’ Concerns

The rehabilitation program director (M.R.) and the facility’s vice-president were interviewed in February 2004, near the end of the pilot project. At that time, they reported the following reasons for establishing a warfarin dosing service: inconsistent warfarin dosing and monitoring at the institution; lack of familiarity with patients and inconsistent coverage by on-call physicians on weekends and statutory holidays; high volume of patients receiving warfarin therapy referred from acute care facilities; no standardized protocol for prevention of deep vein thrombosis (DVT) and no policy for discontinuing anticoagulation (including low-molecular- weight heparin [LMWH]); no on-site anticoagulation expertise; lack of laboratory services on weekends and statutory holidays; a desire to build and expand pharmacists’ scope of practice; a desire to delegate anticoagulation resources from physicians to pharmacists; greater physician support for pharmacy and patients; increased length of stay because of delayed anticoagulation; and desire for physician and staff education.

Data for Baseline Control Group (2002)

The pilot project was originally planned to start in September 2002, so the baseline physician dosing data were collected from March 11, 2002, to July 11, 2002. The purpose of collecting these data was to establish the need for a warfarin dosing service and to characterize physician warfarin management, both within the rehabilitation unit and throughout the hospital. female pink viagra

Table 1. Characteristics of Patients in Baseline Control Group




Characteristic




No.


(%)

of
Patients or Mean (Range)


No. of patients


42


Age (yr)


71.6


(52-92)


Sex


Men


8


(19)


Women


34


(81)


Body weight (kg)


71.4


(42.9-117.6)


Length of stay (days)


27.2


(6-57)


Reason for rehabilitation


Orthopedic surgery


41


(98)


Amputation


1


(2)


Medical history


Deep vein thrombosis or pulmonary
embolism


3


(7)


Cardiovascular disease!


7


(17)


Gastrointestinal disease or peptic
ulcer disease


6


(14)


Cancer


1


(2)

The charts for 42 patients treated in the rehabilitation unit were randomly selected by the Medical Records Department and reviewed by one clinical pharmacist (T.C.). This group included substantially more women than men (34 and 8, respectively) with an overall mean age of 71.6 years, a mean weight of 71.4 kg, and a history of cardiovascular disease (17% of patients), gastrointestinal disease, including pelvic ulcer disease (14%), and DVT or pulmonary embolism (7%) (Table 1). The primary reason for admission was rehabilitation after major orthopedic surgery, and the mean length of the hospital stay was 27.2 days.
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Table 2. Warfarin Use Before and During Admission for Patients in Baseline Control Group (n = 42)




Characteristic of Therapy




No.


(%)

of
Patients or Mean (Range)


Duration of warfarin therapy before


11.5 (1-31)


admission (days)


Duration of warfarin therapy on unit
(days)


26.9 (6-57)


Indication for warfarin


DVT prophylaxis


40 (95)


DVT treatment


2 (5)


Type of warfarin therapy*


Initiation


1 (2)


Maintenance


6 (14)


Transition


35 (83)


No. of medications during admission



11.3


(5-20)


No. of warfarin interactions during
admission


1.5 (1-4)


No. of orders for warfarin during
admission!



425


(10.9/patient)

Warfarin had been initiated (at acute care facilities) a mean of 11.5 days before admission to the rehabilita­tion unit (Table 2). Warfarin was most often prescribed for DVT prophylaxis. Thirty-five patients (83%) were undergoing transition dosing.

During the baseline period, there were a total of 425 warfarin orders, or 10.9 orders per patient, and the mean duration of warfarin therapy was 26.9 days. Patients in the baseline control group were receiving an average of 11.3 concurrent medications (Table 2). The most common interactions with other drugs involved acetaminophen (all 42 patients or 100%), antibiotics (13 patients or 31%), statins (5 patients or 12%), and LMWH (2 patients or 5%).
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Table 3. INR Results for Patients in Baseline Control Group (n = 42)




Variable




Mean (Range)


Baseline INR on admission!


1.90


(1.10-5.10)


No. of INR results during hospital stay


11.3


(3-29)


Time to reach first therapeutic INR (days)


5.3


(1-20)


INR value
(% of
results while receiving warfarin)


Therapeutic
(2.0-3.0)


44.2


(12.5-85.7)


Subtherapeutic
(< 2.0)


46.6


(20.0-71.4)


Supratherapeutic
(3.01-3.99)


7.7


(0-40.0)


Supratherapeutic
(4.0-6.0)


1.1


(0-16.7)


Supratherapeutic
(> 6.0)


0.4


(0-7.7)


Total no. of vitamin K doses


5!


No. of times FFP given


0

The mean baseline INR was subtherapeutic (1.90), but the results for individual patients ranged from subtherapeutic to supratherapeutic (1.10 to 5.10) (Table 3). On average, 11.3 INR results were obtained for each patient during the hospital stay, and it took on average 5.3 days to reach the first therapeutic INR.

For each patient, an average of 44.2% of INR results were within the therapeutic range, 46.6% were subther­apeutic, and 9.2% were supratherapeutic (Table 3). Vitamin K was required a total of 5 times (for 2 patients).

One patient had a nonfatal pulmonary embolism, and another had a major bleeding episode (hematuria, INR = 7.7). There were no deaths in the baseline control group.

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