Despite being the most at risk, older
people are the least likely to receive preventive treatment for stroke.
None of the available stroke risk stratification
particularly well in older people, a recent study reveals.
compared the performance of the commonly used stroke risk stratification
schemes in a contemporary population of older people. It covered 665 patients
aged 75 or over with atrial fibrillation.
Atrial fibrillation is the most common form of
irregular heartbeat. It is caused due to an abnormal heart rhythm and is
associated with stroke and heart failure. Atrial fibrillation risk increases
with age. The prevalence is highest in people aged 85 and
over. Deadly outcomes such as stroke are more common in older patients. A
stroke results when the blood supply to any part
of the brain gets interrupted. People with atrial fibrillation have irregularly
beating heart chambers. This results in dislodging blood clots, which travel to
the brain and cause strokes.
number of risk stratification schemes exist
so as to assess a person's risk of stroke (CHADS2,
CHADS2, NICE, ACC/AHA/ESC etc.). The CHADS2
index is the simplest one. CHADS2 is an acronym for Congestive heart failure,
Hypertension, Age 75 and older, Diabetes and previous Stroke. Risk stratification schemes compute 'stroke risk scores'. CHADS2,
for example, awards a score ranging from 0 to 6. Each risk factor is given
points. Previous stroke adds two points to the score. Based on the score, most
of the people are stratified into risk categories (low, moderate, high) by most
of the risk stratification schemes.
Identifying people with 'high risk' is important since
management of the disease is different for them. International guidelines recommend that all patients
assessed as high risk are offered warfarin, a drug that prevents blood clot
formation. Warfarin belongs to a group of drugs called
vitamin K antagonists, since it reduces blood clotting by inhibiting vitamin K.
The Birmingham Atrial Fibrillation Treatment of
the Aged (BAFTA) trial showed
that among elderly patients with atrial
fibrillation (AF), anticoagulation with warfarin was superior to aspirin for
primary stroke prevention. Dagibatran, rivaroxaban and apixiban are
other new drugs found to have superior efficacy.
Though guidelines insist that high-risk
atrial fibrillation patients are offered vitamin K antagonists in most
circumstances, these drugs remain underused for stroke prevention.
Underuse is more marked in the older population. Better prevention of stroke in older patients with atrial
fibrillation is therefore a priority.
concluded that all the schemes studied had a similar limited ability to predict
the risk of stroke. The deleterious effects would shed a worse impact on the
older population who are at a greater chance to suffer atrial fibrillation and
Based on the study, authors recommend that
clinicians classify all patients over 75 as high risk and offer oral
anticoagulation for these patients until better tools are available. This would
seem more practical than relying on the 'potentially less effective' risk
Source: Performance of stroke risk scores in
older people with atrial fibrillation not taking warfarin: comparative cohort
study from BAFTA trial; FDR Hobbs et al; BMJ 2011; 342: d3653