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10 points. AF & Warfarin practice Profile 2011

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•QOF 2009/10•CHADS2 and GRAPS data from systemone•Admissions – Bradford HES data 2009/10

Data used

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Order of slides1. Incidence2. Prevalence – diagnosed 3. Undiagnosed cases – opportunistic case finding4. Risk profile of AF population in NHSBA – CHADS25. Anticoagulation6. Potentially avoidable strokes7. INR Control8. Patients who might be taken off warfarin9. Secondary care – admissions.

– General non elective admissions– Stroke with AF– GI bleed

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• Point 1 New incident cases of AF

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• 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).

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• Point 2 Prevalence of AF

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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

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Prevalence of AF varies widely across NHSBA practices and is closely correlated with age structure

R² = 0.7732

0.0%0.5%1.0%1.5%2.0%2.5%3.0%3.5%

0% 5% 10% 15% 20% 25% 30% 35%

Prev

alen

ce

% population >65+yrs

Relationship between AF prevalence and age of practice

Prevalence varies between 0.1% of registered population and 2.6%

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• Point 3 Underdiagnosis opportunistic case finding might warrantedthis should be structured and targeted. Opportunistic pulse check is as good as any (Fitzmaurice / SAFE study)

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There are undiagnosed cases. We don’t know the true number, but can estimate it.

Population AF registerObserved

prevalenceExpected AF

registerExpected

prevalence

Potential undiagnosed patients

Airedale 99,688 1834 1.8% 1669 1.7% -165BANCA 120,766 1777 1.5% 1946 1.6% 169City Care 139,261 667 0.5% 1048 0.8% 381Independent13,030 178 1.4% 241 1.9% 63S&W 161,295 1955 1.2% 2230 1.4% 275

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%

The majority of unfound cases can be found in City Care alliance (n=381).

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Number of unfound cases ranges between -49 and 58 per practice (mean = 9)

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Estimated that 90% of true prevalent cases have been diagnosed through QOF. This proportion varies across practices – helpful in informing case finding.

% of the estimated true prevalent AF population that has been diagnosed through QOF

0

20

40

60

80

100

120

140

160

180

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

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Positive (but weak) correlations between list size, age of practice and % of population that is diagnosed.

Practices with older populations tend to have higher proportion of cases that are diagnosed, as do practices with larger populations.

R² = 0.1757

0%

5%

10%

15%

20%

25%

30%

35%

0 50 100 150

% p

op

ula

tio

n >

65

yrs

% of population that is diagnosed

R² = 0.2369

0

5,000

10,000

15,000

20,000

25,000

0 50 100 150

List

siz

e

% of population that is diagnosed

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• Point 4 CHADS2 profile – as a measure of risk.

• Patients with a CHADS2 score and who appear on the AF register

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Profile of all CHADS2 scores available for each practice. CHADS2=2 = 29%, CHADS2 = 6 = 1%.

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%

24%

29%

17%

11%

4% 1%

Patients who appear on the AF register and their CHADS2 score

CHADS2=0

CHADS2=1

CHADS2=2

CHADS2=3

CHADS2=4

CHADS2=5

CHADS2=6

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• Point 5 AnticoagulationGRASP in NHSBA PracticesNumbers who need to be on Warfarin who are currently notNumbers currently on warfarin that might not need to be

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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 score and

AF register

CHADS2 score and AF

regisiter and on warfarin

Patients who need to be on

warfarin1 1,726 735 9912 2,082 1,157 9253 1,218 746 4724 783 501 2825 298 185 1136 48 27 21CHADS≥1 6,155 3,351 2,804CHADS≥2 4,429 2,616 1,813

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40% of prevalent AF patients have CHADS2 of ≥ 1 and are not prescribed warfarin. This varies from practice to practice

0

20

40

60

80

100

120

140

proportion of prevalent patients who are medium or high risk (CHADS2≥=1), not prescribed warfarin but need to be considered for it.

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Point 6Potentially avoidable strokes.

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• 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

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Annually - an extra 107 strokes would potentially avoided if patients with a CHADS2≥ 2 went onto Warfarin134 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 risk of 0% with a CHADSVASc score of 0.

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Point 7 % with good INR control

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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.

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• 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

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• Point 8 Patients who need to be taken off Warfarin

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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).

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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

0.0

2.0

4.0

6.0

8.0

10.0

12.0

14.0

16.0

18.0

20.0

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• 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

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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).

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0

2

4

6

8

10

12

14

16

Adm

issio

ns p

er 1,

000

popu

lation

Admissions where AF is a primary or secondary diagnosis, 2009/10

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

4.0

4.5

Adm

issio

ns p

er 1

,000

pop

ulati

on

Admissions where AF is a primary diagnosis only, 2009/10

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Reasons for admits – where AF is in primary or secondary diagnosis + CV admit (ie excluding ingrowing toenails) – top 15

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• A proportion of non elec admits might be avoided with better rate and rhythm control

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AF StrokesWhat of AF strokes that are admitted.• Strokes with AF in a secondary

diagnosis position• NB – this tells us nothing about AF

strokes that died.

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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

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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)

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Important point to remember (2)RCP Stroke Audit, 2010Factors, 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-sentinel-stroke-audit-2010-public-report-and-appendices_0.pdf

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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 – 4 were taking warfarin

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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.

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Bleed Risk

Many are concerned about bleed risk of patients when on OACHow common IS a bleed?

NB – more work to be done on bleed risk. Chang et al.

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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.

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Summary

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Summary in numbers534k pt registered6411 pt on AF register 1.2%7134 estimated true number – 1.3%est 723 missing pt90% of population diagnosed.

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6155 have CHADS2 of 1 or more, of which 2804 not currently prescribed warfarin – 46% not px4429 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

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107 avoidable strokes if currently non anticoagulated patients with CHADS2 of 2 or more get anticoagulation134 if the threshold for anticoag is CHADS2 of 1 or more

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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.

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c190 AF strokes admitted (from c900 overall) – mostly not taking OAC. Doesn’t take into account deaths.c38 admissions due to bleed in AF

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And so what

Issues to consider in determining “what next”

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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.