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Table 1 Study Characteristics

From: Optimal loading dose for the initiation of warfarin: a systematic review

Study Recruitment
Setting
Eligible Population
(average age)
Inclusion/Exclusion criteria Protocol Outcomes
5 mg vs. 10 mg     
Harrison (1997)
Canada
Inpatients & outpatients 51 patients *
(64 yrs)
%not available
INR target 2.0-3.0 1)Time to INR in range,
2) INR >3.0,
3) Time to reduction in factors II, X and protein C
Crowther (1999)
Canada
Thromboembolism unit 53 patients *
(65 yrs)
47% male
INR target 2.0-3.0. Exclusions: contraindication to warfarin or geographically inaccessible 1) Proportion with INR in range for 2 consecutive days on days 3 & 4, or 4 & 5 and INR not >3.0
Kovacs (2003)
Canada
Outpatient clinics 201 patients with DVT or PE
(55 yrs)
56% male
Exclusions: baseline INR >1.4, thrombocytopenia, <18 yrs, hospitalised, oat in previous 2 wks, high risk of bleeding Primary Outcome:
1) Time to INR >1.9.
Secondary Outcomes:
2) INR in-range by day 5
3) VTE by day 90
4) Major bleeding by 28 days
5)INR >5.0
6)Number of INRs in 28 days
7) Death by 90 dys
Quiroz (2006)
USA
Inpatients 50 patients with DVT or PE
(50 yrs)
54% male
Exclusions: <18 yrs, not available for clinic f/up, warfarin or heparin >36 hrs, creatinine clearances of <30 ml/min, life expectancy <3 mths, high risk of bleeding Primary Outcome:
1) Time to INR >1.9 on 2 consec. days.
Secondary Outcomes:
2) Recurrent VTE at 14 days
3) Death at 14 days
4) Major bleeding at 14 days
5) INR >5 at 14 days
5 mg vs. 2.5 mg     
Ageno (2001)
Canada &Italy
Inpatients 232 patients with heart valve replacement
(64 yrs)
56% male
INR target 2.0 (range 1.5-2.6). Exclusions: baseline INR >1.3 Primary Outcome:
1) % INR >2.6
Secondary Outcomes:
2) Time to INR in range
3) % out of range
4) Vit. K/bleeding/thromboembolic events
5) Dose adjustments/mean daily dose
5 mg vs. calculated dose     
Shine (2003)
USA
Inpatients 90 patients with AF, DVT, PE or other
(61 yrs)
58% male
INR target 2.0-3.0 & INR = 1.4. Exclusion; warfarin in previous 3 months 1)Time to INR in range
2) Hours in hospital
3) Number with INR 2.0-3.0
4) Factor II protein activity
5) Clinical complications
6) INR ever >4.0 or a rise of 2.0 over 2 days to >3.0
Age adjusted     
Roberts (1999)
Australia
Inpatients 65 patients with AF, DVT, PE & other
(74 yrs)
70% male
INR target 2.0-3.0. Exclusions: prolonged diarrhoea, nasogastric/enteral feeds, commencing amiodarone, advanced malignancy, Vitamin K in previous 2 wks Primary Outcome
1)Time to INR in range on 2 consecutive days or if previous day within 0.5
Secondary Outcomes
2) No. with INR >4.0 in first week
3) Dose withheld in wk1
4) No. of days with heparin
Gedge (2000)
UK
Inpatients 127 patients with - AF, DVT, PE & other
(75 yrs)
50% male
INR target 2.0-3.0. Elderly patients with standard indications. 1)Time to INR >2.0
2) Days INR in range
3)Number with INR >4.5
4) Dose prediction day 4
Genotyping     
Hillman (2005)
USA
Inpatient & Outpatients 38 with DVT, PE, AF, other, postoperative orthopaedic
(70 yrs)
45% male
Exclusions: antiphospholipid antibodies, contraindication for warfarin, previous warfarin, liver disease, renal disease, non-Caucasian, <40 yrs. Primary Outcome:
1) Feasibility of dosing model
Secondary Outcomes:
2) % time INR in-range
3)% pts with INR >4
Anderson (2007)
USA
Inpatient & Outpatients 201 with DVT, PE, AF, other, preoperative orthopaedic
(61 yrs)
53% male
INR target 2.0-3.0. Exclusions: <18 yrs, women, pregnant, lactating or child-bearing potential, rifampin within 3 wks, co-morbidities precluding standard dosing (advanced physiological age, hepatic or renal insufficiency/creatine of <25 mg/dl, terminal illness) Primary Outcome
1) % INR out of range/patient
Secondary Outcomes:
2)time to INR >3.2 or VitK
3)%pts in range days 5 &8
4)Number of INR measures & dose adjustments
5) %pts with SAEs - INR ≥4, VitK, major bleeding, thromboembolic events, stroke, MI & death)
Caraco (2008)
Israel
Inpatients 232 with DVT, PE, AF
(58 yrs)
46% male
Exclusions: <18 yrs and baseline INR >1.4 Primary Outcomes:
1) Time to INR >2.0
2) time to stable anticoagulation (defined as 2 INR in-range 7 days apart)
Secondary Outcomes:
3) %Time INR in-range
4) Days INR out of range
5) Major bleeding/VTE events