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Table 1 Old PT-INR based initiation protocol and new initiation protocol modified for the slower responding Fiix prothrombin time (Fiix-NR). Modified from Journal of Thrombosis and Thrombolysis 2019;48:685–9 [44].

From: Replacement of traditional prothrombin time monitoring with the new Fiix prothrombin time increases the efficacy of warfarin without increasing bleeding. A review article

Starting daily dose

on day 1

Normalized ratio

on day 4

Warfarin dose;

Old PT-INR initiation protocol

(mg/day)

Warfarin dose;

New adapted Fiix-NR initiation protocol

(mg/day)*

<  65 year old;

4 mg daily

 

<  1.3

6

5

 

1.3

4

4

 

1.4–1.5

4

3

 

1.6–1.7

4

2

 

1.8–2.5

2

1.0–1.3

 

> 2.5

1.3

Dose skipped and adapted**

≥65 year old;

6 mg daily

 

<  1.3

9

8

 

1.3

6

6

 

1.4–1.5

6

4.5

 

1.6–1.7

6

3

 

1.8–2.5

3

1.5–2.0

 

> 2.5

2

Dose skipped and adapted**

  1. *The Fiix normalized ratio (Fiix-NR) responds slower than the PT-INR due to insensitivity to factor VII reductions. ** Dose usually skipped for 1–2 days and dose then reduced based on rate of rise of the normalized ratio
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Thrombosis Journal

ISSN: 1477-9560

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