VTE: Chronic Therapy

Question 1

How to pick warfarin initiation dose?

Answer 1

look at indication, setting (in vs out pt) and pt factors (especially age)

Question 2

When is there the highest risk of AEs when starting warfarin ?

Answer 2

1st 30 days

Question 3

Which are the 2 main nomograms to use for warfarin initiation

Answer 3

5+ 10mg nomograms

— 4mg one is also available: for afib (but good for old people that are 80-90

Question 4

Which nomogram is better for old people: 5 or 10mg

Answer 4

5mg

Question 5

How slowly do we want INR to increase when starting warfarin

Answer 5

0.1-0.5 per day max

Question 6

When starting warfarin, if my INR is going up by 1.0 per day; what does this mean in regards to my current warfarin dose?

Answer 6

its too high — need to decrease dose

Question 7

Positives + negatives for 4mg nomogram

Answer 7

good for old people (80-90)
—- lower starting dose

• for first 3 days: need to take W dose at 6pm + INR at 10am

Question 8

What is the warfarin transition phase

Answer 8

time when warfarin getting to SS

Question 9

How long does it take to get to SS on warfarin

Answer 9

about 3 wks

Question 10

Why does it take so long to get to SS on warfarin

Answer 10

because it depends on the t1/2 of W (48 hours) + t1/2 for clotting factors (II) disappearance (72 hours)

Question 11

What impacts time between INR dosing when on transition stage of dosing

Answer 11

stability of INR + pt RF

Question 12

How often should INR be done during the first month of warfarin therapy

Answer 12

twice a week at least
—- can increase time between tests as stability of INR increases (stays in range etc)

— no set algorithm

Question 13

T or F: during the transition phase of W, there is a set algorithm we can use for dosing

Answer 13

F- no set algorithm
—- kind of go with vibes and figure shit out

— there is a study that the 10mg nomograms gives a good estimate of MD

Question 14

What is the maintenance phase of W

Answer 14

Once reach SS (months 1-3— indefinitely)
— generally takes 6-8 weeks to get to this phase

Question 15

What is the longest time between INR tests

Answer 15

4-6 wks

Question 16

T or F: doing INR tests every 12 weeks is just as good as every 4-6 wks (ex// spend same time in therapeutic range etc)

Answer 16

F - less time in therapeutic range

—- do every 4-6 wks max

Question 17

What are the different approaches to adjusting warfarin dosing

Answer 17

1) Respond to INR: if high —- lower dose etc
2) Use computerized warfarin management system (only works once in M phase) : ex/ Posologic
3) Systematic approach

Question 18

What is the systematic approach to warfarin management

Answer 18

If INR out of range:
- figure out why
- determine pts risk of thrombosis
- consider how far out of range it is
- pick best dosing strategy going forward: do nothing,1x dose change Or change MD totally

Question 19

What factors can impact INR

Answer 19

non-adherence
changes in meds
illnesses
lifestyle changes (alcohol, exercise)
Diet
Stress

Question 20

What is the risk of thrombosis in the 1st month following acute VTE if on no therapy

Answer 20

40% monthly risk

Question 21

Risk of thrombosis in the first three months following acute VTE (no therapy)

Answer 21

10% per 2 months

Question 22

Risk of recurrent VTE following acute VTE if no therapy

Answer 22

15% per year

Question 23

When would you not adjust the W dose after INR is out of range

Answer 23

• if isolated + barely out of range (< 0.5)
  —— especially best if later on in therapy (not during acute therapy 1-3 mths —- highest risk of thrombosis during this time)

Question 24

When would you change MD of W if INR is out of range

Answer 24

If super out of range (> 0.5) OR during acute therapy (1-3 mths)

Question 25

T or F: doing a one time dose change then returning to MD is the best option for acute VTE therapy

Answer 25

T- if in the 1-3mth time period following VTE ; best to just do a one time change + check INR in the next couple days instead of changing whole MD

Question 26

T or F: if changing pt’s MD of W, its normally changed based on % of patient’s monthly dose

Answer 26

F- weekly —- if +/- 0.5 out of range: 5-10% change —- if >/= 0.5 out of range: 10-20% change ** consider pts strengths of tablets — may take several weeks to see changes of new MD due to t1/2

Question 27

What are the 5 different types of DIs with W

Answer 27

1) Impair platelet fxn: no change to INR 2) reduce Vit K synthesis in GI: increase INR 3) Impact W metabolism: CYP2C9 4) Injury to GI mucosa: no change to INR 5) impact Vit K reductase/epoxide : increase INR

Question 28

T or K: Antibiotics can cause a decrease in INR

Answer 28

F- increase if anything due to decrease Vit K made in gut

Question 29

T or F: ASA can cause a huge decrease in INR + bleeding risk which is why we don’t use W + ASA together

Answer 29

F- does increase bleeding risk by 50%(impact platelet fxn) but no impact on INR

Question 30

What is some practical way to approach someone starting a new med when on warfarin

Answer 30

if don’t think DI —- just have them come in in 1 wk to check INR (check more often)

Question 31

When is the only times we can’t stop ASA if pt on Warfarin

Answer 31

Recent coronary syndrome, recent stent/bypass or mechanical heart valve —— giving heart surgery shit

Question 32

T or F: if INR is > 5 we see a major increase in life threatening bleeding

Answer 32

F- if > 5: increase in intracranial bleeding —- if > 6: increase risk of life threatening bleed in next 2 weeks by 4%

Question 33

What are the 2 approaches to take if INR > 4 + not bleeding

Answer 33

1) skip 1-2 warfarin doses + repeat INR daily till < 4 2) Vitamin K dose (1-2.5mg)

Question 34

T or F: PO Vitamin K is the preferred way to treat high INR in Canada

Answer 34

F- we don’t have PO Vitamin K only IV/SC —- can mix with water + give Po if want PO —- slower response (12-24hrs ) vs 6 with IV

Question 35

What is the best way to correct INR if have life-threatening bleed + on W

Answer 35

fresh frozen plasma or recombinant clotting factors

Question 36

T or F: 1mg dose of Vitamin K does reduce INR back to < 4 faster then skipping W dose BUT doesn’t reduce risk of bleeding/ impact thrombosis risk

Answer 36

T- no real benefit in reality — doesn’t help reduce risk of bleeding — Jeff normally gives Vit K if INR > 6 or if person at risk of slow decrease in INR

Question 37

T or F: Older pt normally correct their INR faster

Answer 37

F - slower decrease in INR if > 65

Question 38

T or F: having a lower weekly dose of W (< 3mg/day) puts you at a increase risk for slower INR decrease

Answer 38

T

Question 39

Other than age + W dose, what other factors impact how fast an INR decreases

Answer 39

how far out of range it is decompensated HF active cancer decrease oral intake

Question 40

What is the general recommendation when it comes to Vit K food and W

Answer 40

try to take consistent amounts

Question 41

What to do if miss W dose

Answer 41

Double up dose on the day you realize + let them know when get INR checked

Question 42

T or F: DOACs are better than W because they are all dosed daily

Answer 42

F- Apixaban is BID — riva: BID for first 21 days then daily after

Question 43

Is there an antidote for DOACs

Answer 43

no

Question 44

Can you use DOACs if you have renal failure (CrCL< 30)

Answer 44

NO - renally excreted

Question 45

Advantages of DOACs to W

Answer 45

quicker onset, no monitoring + fewer Dis

Question 46

Risk of recurrent VTE in provoked VTE after finishing 3 mths of therapy

Answer 46

< 3 % year —- low risk —- generally 3 mths of therapy is good

Question 47

Length of anticoag therapy if pt had one unprovoked VTE (especially PE)

Answer 47

can be indefinitely - risk of recurrence is 10% a year — if recurrent VTE: get indefinitely (15% recurrence per year)

Question 48

What is the best therapy option for 2nd prevention of VTE (after finish 3 mths of therapy)

Answer 48

W: with INR 2.5 (decrease VTE risk by 80-90%)

Question 49

Can we use ASA as 2nd prevention of VTE

Answer 49

Yes - 100mg daily - not very effective (decrease risk by 30%)

Question 50

Preferred therapy option for pregnant people

Answer 50

LMWH or UFH - W + DOACs are CI

Question 51

Best option for pt with active cancer if need chronic therapy

Answer 51

LWMH