Dr Alan Begg reviews the changes to the atrial fibrillation domain in the GMS contract 2012/13 and highlights how they will improve appropriate use of anticoagulation therapy

Atrial fibrillation (AF) is the most commonly sustained arrhythmia in the UK, affecting almost 1 million people and accounting for up to 2.5% of total NHS expenditure.1 It is associated with a doubling of the mortality risk and shortens life span by around 5 years in men and 8 years in women.1 The most frequent consequence of AF is stroke. Individuals with AF have a five-fold increased risk of stroke compared with those who do not have AF, and the event is more likely to be disabling or fatal.1 Overall, there are 110,000 strokes each year in England; in Scotland, the incidence may be even higher.1,3 It is estimated that 15% of all strokes are caused by AF.3

An analysis of UK general practice data revealed that 11% of patients who experienced a stroke previously had AF coded as a risk factor. These individuals tended to be older than the overall stroke cohort, with an average age at the time of their first stroke of 82 years for women and 77 years for men.2 Furthermore, in people aged over 70 years, 56-day mortality rates following stroke were significantly higher than in individuals without coded AF—32% for men and 23% for women.2

In addition to the heightened risk of stroke, left ventricular function deteriorates over time in patients with AF, which results in a greater than three-fold increase in risk of heart failure.1

QOF 2012/13 changes

Reflecting the high risk of stroke associated with AF, significant changes have been made to the AF indicators for 2012/13 (see Table 1).4,5 The total number of points in the AF domain remains the same, with 27 points available, but there are now four indicators rather than three:

  • AF4 has been retired—this indicator specified confirmation of diagnosis by an electrocardiogram (ECG) or specialist opinion
  • A new indicator, AF5, involves carrying out a risk assessment using the CHADS2 risk-stratification scoring system
  • AF3 has been replaced with AF6 and AF7, which relate to use of antithrombotic therapy relative to the CHADS2 score.

AF1

The requirement remains for practices to produce a register of patients with AF. This should include all patients with:5

  • paroxysmal AF—an event that self-terminates usually within 48 hours
  • persistent AF—when an episode lasts longer than 7 days
  • permanent AF—when the long-term presence of the arrhythmia is accepted by the patient and physician.

Although there is no longer any requirement to confirm diagnosis as a separate indicator, diagnosis of AF requires a 12-lead ECG. This should be performed by a professional with the necessary skills and training, as should the interpretation.6 Interpretation programmes for ECGs may not detect all cases of AF. A Health Technology Assessment programme carried out in the UK showed that interpretation programmes have an 87.3% sensitivity and a 99.1% specificity, with a predictive value of 89.5% for correct diagnosis against the gold standard of cardiologist reporting.7 However, GPs are good at correcting false-positive diagnoses made by an interpretive ECG recording.8


AF5

The CHADS2 risk-assessment scheme uses a point system that correlates with stroke risk. 9,10 It is based on clinical risk factors for stroke that have evolved from the AF Investigators and Stroke Prevention in Atrial Fibrillation (SPAF) investigators’ criteria. The score can be recorded using the Read code 38DE.11.5 Reference should be made to the actual numerical score rather than referring to patients as low, moderate, or high risk.

The CHA2DS2-VASc system extends CHADS2 by including additional risk factors that may influence the decision whether or not to use anticoagulant therapy.10,11 Despite the QOF recommending the use of the CHADS2 score, Healthcare Improvement Scotland advises that the CHA2DS2-VASc scoring system should be used to assess the risk in patients with non-valvular AF.12

AF6

For the purposes of QOF, aspirin, dipyridamole, and clopidogrel are acceptable antiplatelet agents in people with AF.5

The Birmingham Atrial Fibrillation Treatment of the Aged (BAFTA) study showed that warfarin was superior to aspirin 75 mg daily, reducing fatal or disabling stroke (ischaemic or haemorrhagic), intracranial haemorrhage, or clinically significant arterial embolism by 52%.13 Furthermore, the study found no difference in the risk of major haemorrhage between warfarin and aspirin.13 The guidance for QOF accepts that warfarin is more effective than aspirin for prevention of stroke, achieving a 66% risk reduction compared with 22%, respectively.5 In the study that validated the CHADS2 score, the authors were unable to confirm statistically significant efficacy for aspirin in preventing stroke although they stated that it may be suitable for individuals aged 75 years or older who are not suitable for warfarin therapy.9

The European guidelines for the management of AF recommend a more comprehensive risk factor approach using CHA2DS2-VASc. Although it accepts that there is benefit from using aspirin in patients with a CHADS2 score of one, the guidance states that if the CHA2DS2-VASc score equals one, anticoagulation rather than aspirin is preferred.10

In its recent UK consensus statement, the Royal College of Physicians of Edinburgh made a number of key recommendations on AF (see Table 4), including: ‘Aspirin should not be used for stroke prevention in AF.’14

AF7

The benefits of anticoagulation therapy in reducing stroke risk in patients with a CHADS2 score greater than one are not disputed. In the analysis of UK general practice data mentioned previously, of the patients coded with AF prior to their first stroke, 59% of women had a CHADS2 score of two or above compared with 42% of men.2 Additionally, 25% of AF-coded patients were prescribed anticoagulants before their stroke (22% of women and 29% of men).2 Anticoagulant prescribing rate did not correlate with CHADS2 score prior to a stroke, but it did increase in both men and women after a stroke. Antiplatelet therapy was prescribed to 52% of patients coded with AF and prescribing of antiplatelet therapy increased steeply with rising CHADS2 score.2

Warfarin, phenindione, and dabigatran are acceptable anticoagulants under QOF.5 Healthcare Improvement Scotland recommends warfarin as the anticoagulant drug of choice, however it has recommended the use of both dabigatran and rivaroxaban in certain circumstances (see Table 5); 12 however the latter drug is not mentioned in the QOF guidance. If rivaroxaban is recommended as a first-line alternative to warfarin in certain areas of Scotland, such as Tayside, consideration will need to be given as to whether patients prescribed this drug for clinically accepted reasons will be exempted from the AF7 indicator.

Bleeding risk

The decision on whether to commence anticoagulation should be made after a full discussion with the patient and their family, taking into account the risks and benefits. However, rates of intracerebral haemorrhage in elderly patients taking anticoagulants are lower than in the past, perhaps due to better monitoring and control of risk factors.10

Patients should be assessed for bleeding risk using the currently favoured HAS-BLED scoring system (see Table 6). 10,15 This tool is based on the cohort of the EuroHeart Survey and a score greater than three indicates the need to exercise caution and ensure regular reviews if antithrombotic therapy is initiated.10


Table 1: QOF indicators for atrial fibrillation5
No.
Indicator
Points
Payment stages
Records
AF1 The practice can produce a register of people with AF 5
Initial diagnosis
AF5 The percentage of patients with AF in whom stroke risk has been assessed using the CHADS2 risk stratification scoring system in the preceding 15 months (excluding those whose previous CHADS2 score is greater than 1) 10 40–90%
Ongoing management
AF6 In those patients with AF in whom there is a record of a CHADS2 score of 1 (latest in the preceding 15 months), the percentage of patients who are currently treated with anticoagulation drug therapy or antiplatelet therapy 6 50–90%
AF7 In those patients with AF whose latest record of a CHADS2 score is greater
than 1, the percentage of patients who are currently treated with anticoagulation therapy.
6 40–70%
Total points 27
AF=atrial fibrillation
Table 2: CHADS2 and CHA2DS2-VASc10
Risk factor Score Risk factor Score
C Congestive heart failure 1 C Congestive heart failure/left ventricular dysfunction 1
H Hypertension 1 H Hypertension 1
A Age ?75 years 1 A2 Age ?75 years 2
D Diabetes mellitus 1 D Diabetes mellitus 1
S2 Prior stroke or TIA 2 S2 Stroke/TIA/thrombo-embolism 2
Maximum score 6 V Vascular disease 1
A Age 65–74 years 1
Sc Sex category (i.e. female) 1
Maximum score 9*
TIA=transient ischaemic attack
*Maximum score is 9 since age may contribute 0, 1, or 2 points.
Reproduced with kind permission from Oxford University Press
Table 3: Stroke rate associated with CHADS2 and CHA2DS2 VASc score10
CHADS2 score Adjusted stroke rate (%/year) CHA2DS2 VASc score Adjusted stroke rate (%/year)
0 1.9 0 0
1 2.8 1 1.3
2 4.0 3 3.2
3 5.9 4 4.0
4 8.5 5 6.7
5 12.5 6 9.8
6 18.2 7 9.6
8 6.7
9 15.2
Reproduced with kind permission from Oxford University Press

Table 4: Key recommendations from the RCPE UK Consensus Conference on row atrial fibrillation14
  • Detection of AF needs to be improved, ideally with the introduction of a national screening programme
  • Oral anticoagulation use in AF needs to be increased
  • Improved patient engagement in self-management of AF is required
  • Aspirin should not be used for stroke prevention in AF
  • In deciding whether to control rate or rhythm, the goal should be relief of symptoms.
RCPE=Royal College of Physicians of Edinburgh; AF=atrial fibrillation
Table 5: When new anticoagulant agents should be considered12
  • Poor INR control not due to poor compliance
  • Allergy or intolerable side effects from warfarin
  • Patient groups in whom the use of warfarin is logistically challenging.
INR=international normalised ratio
Table 6: HAS-BLED bleeding risk score10
Clinical characteristic Points
H Hypertension (SBP >160 mmHg) 1
A Abnormal renal and liver function (1 point each) 1 or 2
S Stroke 1
B Previous bleeding history or predisposition to bleeding 1
L Labile INRs 1
E Elderly—age >65 years 1
D Certain drugs or alcohol abuse 1 or 2
Maximum 9 points
SBP=systolic blood pressure; INR=international normalised ratio
Reproduced with kind permission from Oxford University Press
Table 7: Comparable end points of stroke or systemic embolism of new anticoagulants versus warfarin18-20
Hazard
ratio
95% confidence interval p value for non-inferiority p value for superiority
Dabigatran etexilate
110 mg twice daily
0.90 0.74 to 1.10 <0.001
Dabigatran etexilate
150 mg twice daily
0.65 0.52 to 0.81 <0.001
Rivaroxaban
20 mg daily
0.80 0.74 to 1.03 <0.001 =0.117
Apixaban
5 mg daily
0.79 0.66 to 0.95 =0.01

Newer anticoagulant agents

Two new oral anticoagulant agents have been licensed for use in the UK for the prevention of stroke and systemic embolism in people with non-valvular AF and have been approved for use by NICE; these are:16,17

  • dabigatran etexilate (which inhibits the thrombin enzyme)
  • rivaroxaban (which directly inhibits activated factor X).

A further agent, apixaban, has a similar mechanism of action to rivaroxaban, and is expected to receive its licence later this year. The comparative clinical effectiveness of these agents versus warfarin is illustrated in Table 7. 18-21 A similar comparison of the risk of major bleeding would favour the 110 mg dose of dabigatran and 5 mg daily dose apixaban over warfarin.18-21

Dabigatran and rivaroxaban have advantages over warfarin in that the dosing regimens are uncomplicated, there is no need for anticoagulation monitoring, and a more stable level of anticoagulation is achieved. Furthermore, they have a rapid onset of action (2–4 hours after the first dose) and the therapeutic effect is lost 24–48 hours after the dose.11

Conclusions

All patients with risk factors for AF should have their pulse taken at routine clinical consultations. If there is any suspicion of an irregular pulse, the patient should undergo a 12-lead ECG.

The 2012/13 changes to the QOF AF indicators are an important step forward because patients with AF are now being formally assessed for risk to ensure that people who would benefit from anticoagulants receive this therapy. The revisions also provide an opportunity to consider the use of newer agents in those for whom warfarin is not appropriate.

  • Atrial fibrillation is a common and easily identified risk factor for ischaemic stroke
  • Correct anticoagulation or thromboprophylaxis in atrial fibrillation can reduce the incidence of stroke and the considerable associated healthcare costs
  • Commissioners could use the changes to the QOF criteria as an opportunity for an educational program for primary care providers that covers:
    • opportunistic case finding (e.g. in flu clinics, pharmacies)
    • ECG interpretation
    • CHADS2 and HAS-BLED scoring systems
    • the indications and risk–benefit profiles for warfarin, aspirin, and the newer agents
  • Local formularies should specifically include the NICE-recommended indications for the newer agents, which are considerably more expensive than warfarin or aspirin, but can be more effective in certain circumstances
  • Some of the expenditure from the newer agents could be mitigated by reduced commissioner costs for warfarin monitoring in cases where these agents replace warfarin
  • Tariff cost for acute stroke = £4208 (AA22Z).a
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