10 points. AF & Warfarin practice
Profile 2011
1
Data used
•QOF 2009/10
•CHADS2 and GRAPS data from
systemone
•Admissions – Bradford HES data
2009/10
2
Order of slides
1.
2.
3.
4.
5.
6.
7.
8.
9.
Incidence
Prevalence – diagnosed
Undiagnosed cases – opportunistic case finding
Risk profile of AF population in NHSBA – CHADS2
Anticoagulation
Potentially avoidable strokes
INR Control
Patients who might be taken off warfarin
Secondary care – admissions.
–
–
–
General non elective admissions
Stroke with AF
GI bleed
3
• Point 1
New incident cases of AF
4
• A practice with 10,000 patients would expect
to diagnose 7-8 new AF patients per year.
• This would vary depending on age profile, CV
and other risk profile.
• The increase might be attenuated through
improved CV risk management.
• This would mean approximately. 395 new
incidents a year in Bradford (ranging between
1 and 15 new cases per practice).
5
• Point 2
Prevalence of AF
6
09/10 prevalence of AF was 1.2%
(95%CI 1.23 – 1.17)
6,411 cases.
Older practices (proportion register
>65+yrs) showing higher prevalence –
linear relationship between age profile
and prevalence
7
Prevalence of AF varies widely across
NHSBA practices and is closely
correlated with age structure
Prevalence
Relationship between AF prevalence
and age of practice
3.5%
3.0%
2.5%
2.0%
1.5%
1.0%
0.5%
0.0%
Prevalence
varies between
0.1% of
registered
population and
2.6%
R² = 0.7732
0%
5%
10%
15%
20%
25%
30%
35%
% population >65+yrs
8
• Point 3
Underdiagnosis
opportunistic case finding might
warranted
this should be structured and
targeted.
Opportunistic pulse check is as good
as any (Fitzmaurice / SAFE study)
9
There are undiagnosed cases. We
don’t know the true number, but can
estimate it.
Population AF register
Airedale
99,688
1834
BANCA
120,766
1777
City Care 139,261
667
Independent13,030
178
S&W
161,295
1955
Observed
prevalence
1.8%
1.5%
0.5%
1.4%
1.2%
Potential
Expected AF Expected undiagnose
register prevalence d patients
1669
1.7%
-165
1946
1.6%
169
1048
0.8%
381
241
1.9%
63
2230
1.4%
275
2500
2000
Number of patients
Estimated true prevalence is 1.3%
(nationally thought to be about 1.7 to
1.8%)
Expected cases (compared to an age
standardised population) 7,134 (diff+
723) or 1.3%
1500
1000
Number of diagnosed and
275
potentially undiagnosed AF patients
169 in NHS Bradford and
in each alliance
Airedale
1834
500
The majority of unfound cases can be
found in City Care alliance (n=381).
0
-500
1777
667
-165
1955
381
63
178
BANCA City CareIndependent S&W
10
Potentia…
Alliance
Number of unfound cases ranges
between -49 and 58 per practice (mean
= 9)
Number of
patients: 723
Percentage:
10%
Number of diagnosed and potentially undiagnosed
AF patients in the PCT
Diagnosed
Number of
patients:
6,411
Percentage:
90%
Potentially
undiagnosed
11
Estimated that 90% of true prevalent
cases have been diagnosed through
QOF. This proportion varies across
practices – helpful in informing case
finding.
Practices with small list
sizes are, as a rule, have
a low proportion of cases
that are diagnosed.
Practices with a large list
size have a high
proportion of expected
that is diagnosed – or
have diagnosed more
than the expected
prevalent pop
12
35%
25%
R² = 0.1757
20%
15%
10%
5%
0%
0
50
100
150
% of population that is diagnosed
25,000
20,000
List size
% population >65yrs
30%
Positive (but weak)
correlations between list
size, age of practice and
% of population that is
diagnosed.
15,000
R² = 0.2369
10,000
5,000
0
0
50
100
% of population that is diagnosed
150
Practices with older
populations tend to have
higher proportion of
cases that are
diagnosed, as do
practices with larger
populations.
13
• Point 4
CHADS2 profile – as a measure of
risk.
• Patients with a CHADS2 score and
who appear on the AF register
14
Profile of all CHADS2 scores
available for each practice.
Patients who appear on the AF
CHADS2=2 = 29%,
register and their CHADS2 score
CHADS2 = 6 = 1%.
4%
1%
11%
Practices generally have a
similar CHADS2 profile as
district average.
There are no significant
differences. Differences are
due to small numbers and
random variation
15%
CHADS2=0
CHADS2=1
CHADS2=2
17%
24%
CHADS2=3
CHADS2=4
CHADS2=5
29%
CHADS2=6
15
• Point 5
Anticoagulation
GRASP in NHSBA Practices
Numbers who need to be on Warfarin who are
currently not
Numbers currently on warfarin that might not
need to be
16
Based on CHADS2≥1, number of
patients who need to be on Warfarin =
2,804.
Based on CHADS2≥2, number of
patients who need to be on Warfarin =
1,813.
CHADS2 score
CHADS2
and AF
Patients who
CHADS2 score and regisiter and need to be on
score AF register on warfarin
warfarin
1
1,726
735
991
2
2,082
1,157
925
3
1,218
746
472
4
783
501
282
5
298
185
113
6
48
27
21
CHADS≥1
6,155
3,351
2,804
CHADS≥2
4,429
2,616
1,813
17
40% of prevalent AF patients have
CHADS2 of ≥ 1 and are not prescribed
warfarin. This varies from practice to
practice
proportion of prevalent patients who are medium or high risk (CHADS2≥=1), not
prescribed warf arin but need to be considered f or it.
140
120
100
80
60
40
20
0
18
Point 6
Potentially avoidable strokes.
19
• We know there are avoidable strokes
through putting people on OAC who
need to be
• What is the impact of getting those
who need to be on Warfarin on to
Warfarin
20
Annually - an extra 107 strokes would
potentially avoided if patients with a
CHADS2≥ 2 went onto Warfarin
134 strokes if patients with CHADS2 ≥ 1
were prescribed OAC.
NNT taken from AFA - Anticoagulation and
Bleeding risk – Guidelines for Medical
Professionals, 2009 and applied to local
CHADS2 scores.
OAC threshold is an issue still under discussion –
Treat at CHADS2 = 2 annual relative risk:-4% (Gage)
however many now treat at 1 (annual relative risk:-2.8%). With the move to
CHADSVASc treatment is recommended at scores of 2 (annual relative risk
of 1.9%) and suggested at a score of 1 (annual relative risk of 0.7%). Even at
CHADS score of 0 the annual relative risk is 1.9% compared with a relative
21
risk of 0% with a CHADSVASc score of 0.
Point 7
% with good INR control
22
NICE guidance states that a30% of
patients on Warfarin have poor control
(therefore assumed 70% have good).
The estimated number of CHADS2≥ 2
patients on the AF register and on
Warfarin with good control is
approximately 1,831, with 2,341 for
CHADS2 ≥ 1.
23
• Estimated that 10% -15% of
patients would be unable to
attain good control with
improved warfarin use.
• Ie half of the 30% of currently
diagnosed cohort who have poor
INR control now - might be
candidates for new OACs
24
• Point 8
Patients who need to be taken off
Warfarin
25
Based on CHADS2=0 and on AF
register and on Warfarin.
398 patients need to be taken off
Warfarin – 10.6% of patients with a
CHADS2 score on the AF register and
on Warfarin.
Ranges from 0 to 29 patients per
practice (mean = 5).
26
A mean of 6% prevalent AF patients
ARE prescribed Warfarin and might
not need to be
a mean of 6% of prevalent AF patients who ARE prescribed warfarin that might not need to be
20.0
18.0
16.0
14.0
12.0
10.0
8.0
6.0
4.0
2.0
B8
37
0
B8 0
36
2
B8 1
30
4
B8 2
30
3
B8 2
36
4
B8 7
36
6
B8 1
36
3
B8 8
30
0
B8 5
30
4
B8 5
36
2
B8 7
30
0
B8 7
30
5
B8 2
36
4
B8 1
30
5
B8 6
30
6
B8 1
30
1
B8 1
30
4
B8 4
30
1
B8 6
30
3
B8 0
30
0
B8 9
30
3
B8 7
36
2
B8 8
30
3
B8 1
30
1
B8 5
30
5
B8 8
30
2
B8 7
36
26
0.0
27
• Point 9
Non elective AF admissions
• Dataset is based on extracts from
local admissions, 2009/10
• ICD-10 code I48X used in either a
primary or secondary position
28
09/10 – Approximately 3,347
admissions (average 42 per practice) to
hospital where AF was a primary or
secondary diagnosis. Of these, 453
were recorded as a primary diagnosis.
Variation between practices in
admission rates, between 0.4 and 13.6
per 1,000 population (Bradford mean =
6.4 per 1,000).
29
16
14
12
10
8
6
4
2
0
Admissions where AF is a primary
diagnosis only, 2009/10
Admissions per 1,000 population
Admissions per 1,000 population
Admissions where AF is a primary or
secondary diagnosis, 2009/10
4.5
4.0
3.5
3.0
2.5
2.0
1.5
1.0
0.5
0.0
30
Reasons for admits – where AF is in
primary or secondary diagnosis + CV
admit (ie excluding ingrowing toenails)
– top 15
31
• A proportion of non elec admits
might be avoided with better rate
and rhythm control
32
AF Strokes
What of AF strokes that are admitted.
• Strokes with AF in a secondary
diagnosis position
• NB – this tells us nothing about AF
strokes that died.
33
190 admissions where primary diagnosis
Stroke (ICD 10 code I60-I67) and secondary
diagnosis AF (ICD 10 code I48X).
Estimated that the majority of these (>90%)
NOT taking OAC.
Low practice numbers (mean = 2 per
practice) therefore issues around reliability
and further use.
Possible low numbers due to miscoding /
undercounting of secondary diagnosis
codes.
45 admits for TIA where AF is secondary dx
34
Important point to remember (1)
• Approx 15% of all strokes are due to / in
AF pt
• In NHSBA – 920 strokes admitted in
09/10
• AF strokes are more serious - more likely
to end in death and disability
• With anticoagulation AF strokes are
significantly less likely (though not
completely avoidable)
35
Important point to remember (2)
RCP Stroke Audit, 2010
Factors, Medication Pre-Admission
• Vascular risk factors were present in 81% of patients with previous
stroke/TIA (29%) and hypertension (57%) being the most frequent
conditions. Only 27% of patients known to have atrial fibrillation
(AF) prior to admission with their stroke (21%) were on
anticoagulants.
• Comment: 81% of patients admitted with stroke have a history of
known vascular risk factors, with 29% having had previous stroke or
TIA and 57% with hypertension. Only (27%) who were recorded as
having atrial fibrillation (AF) prior to stroke were taking warfarin
which indicates again the failure to provide large numbers of people
at risk of stroke because of AF with effective prevention. Patients
are dying and having disabling strokes because of our failure to
anticoagulate people appropriately
• http://www.rcplondon.ac.uk/sites/default/files/national-sentinelstroke-audit-2010-public-report-and-appendices_0.pdf
36
Important point to remember (3). BTH 2010 audit
of AF patients in AntiCoag clinic. Key points:
•
•
•
•
•
950 patients with AF in the clinic in BTH
In 2008 there were 4 ischeamic strokes (chance of avoiding a stroke while anticoagulated in the clinic
99.6%)
In 2009 there were 6 ischeamic strokes and 2 haemorrhagic strokes. The haemorrhagic strokes were both
in patients with mechanical heart valves not AF (hence high range INR)
Of the 2009 cohort of the 6 ischeamic strokes
– 2 had INRs of 1 (i.e. Not complying with therapy)
– 2 had INR in a sub therapeutic range
– 1 was in therapeutic range
– 1 was above therapeutic range (3.8 so with in a range which has been previously studied and found
to be effective)
In the 2009 cohort of the 2 haemorrhagic strokes ( recall - the annual incidence of intracranial
haemorrhage is 0.1 per 1000 ( 0.06 in males and 0.13 in females)- Nilsson OG et al 2000):
– 1 had an INR in range
– 1 had an INR of 14 and died
•
In 2009 the audit considered patients who had been taken off Warfarin as it was ‘too dangerous to
continue)
– 9 patients who had been taken off anticoagulants due to this risk suffered an ischeamic stroke
•
In 2010 the audit also considered the AF related stroke (this has also been looked at with larger number in
St Mary’s and Imperial Hospital London):
– 67 patients had an ischeamic stroke with AF
– 59 patients had a CHADS2 score of 2 or greater
37
– 4 were taking warfarin
Point (3) reinforced - Summary of BTH
audit
• Asprin doesn’t work. Of the AF strokes admitted,
almost all were taking asprin.
• Warfain is effective in preventing 99% of strokes
• 9 strokes in the BTH cohort who were taken off
warfarin because it was too dangerous.
• Dozens of AF strokes in patients not taking warfarin.
• Many fear risk of OAC
• At Lukes cohort, the risks of being on warfarin are far
outweighed by the risks of NOT being on it if the
patient is at medium / high risk of stroke.
38
Bleed Risk
Many are concerned about bleed
risk of patients when on OAC
How common IS a bleed?
NB – more work to be done on bleed
risk. Chang et al.
39
38 admissions where primary diagnosis
is GI haemorrhage (ICD 10 code K92.2)
and upper GI bleed (K22, K25-29) or AF
and a secondary diagnosis of AF or GI
bleed.
Very low practice numbers (mean =
0.5 per practice) therefore issues
around reliability and further use.
40
Summary
41
Summary in numbers
534k pt registered
6411 pt on AF register 1.2%
7134 estimated true number – 1.3%
est 723 missing pt
90% of population diagnosed.
42
6155 have CHADS2 of 1 or more, of
which 2804 not currently prescribed
warfarin – 46% not px
4429 have CHADS2 of 2 or more, of
which 1813 not currently prescribed
warfarin – 41%
398 have CHADS2 of 0 and are
prescribed warfarin – might be taken
off
43
107 avoidable strokes if currently
non anticoagulated patients with
CHADS2 of 2 or more get
anticoagulation
134 if the threshold for anticoag is
CHADS2 of 1 or more
44
Estimated that 10% of current
anticoagulated CHADS2 of 2 or
more might be eligible for new OAC
– 262 patients.
Drug cost of c£900 – minus INR
clinic cost.
45
c190 AF strokes admitted (from
c900 overall) – mostly not taking
OAC. Doesn’t take into account
deaths.
c38 admissions due to bleed in AF
46
And so what
Issues to consider in determining
“what next”
47
For a start
• Targeted case finding – opportunistic pulse checks.
• GP education
• Longitudinal dataset needed. How have things
changed over time. How might it change in the
future
• Continued push for improved OAC
• Careful and measured introduction of new agents?
• Quality improvement project. Primary care focused.
Area of emphasis – case finding, OAC, INR. Q
measures being determined.
48