Unruptured Aneurysms
G Narenthiran
L Alakandy
J P Holland
Greater Manchester Neurosciences Centre
Hope Hospital
Salford
Tools for estimating the
Life-time risk of rupture
&
Effect of intervention on life-expectancy
Unruptured aneurysms
• Increasing numbers being diagnosed
• 45% - 80% of patients with ruptured
aneurysm may die
• Not all rupture
• Treatment morbidity 0-16%; mortality 025%
• Treat those at high risk of rupture
ISUIA 2003
•
•
•
•
•
•
•
•
Prospective
Multi-centre
1692 patients did not have treatment
Selection bias
Not randomised
Aneurysms < 2mm not included
Mean duration of follow-up was 4.5 years
Patients who subsequently underwent treatment
excluded from analysis
• Included only North America and Europe
ISUIA, 2003
• The best we have
• Findings of ISUIA (2003), could be
incorporated into the global view of UIA
• Considered along with other data
pertaining to the patient
Objective
• Tools for calculating rapidly at:
• Neurovascular MDT meetings
• Clinics
Method
Cumulative risk (%) = 100 x {1- [(1-annual risk)/100]^years}
Maths of Probability
Annual risk of rupture = 2%
Annual risk of no-rupture = 98%
2
1.96
100
100 × 0.98
98
100 × 0.98 × 0.98
96.4
100 × 0.98 × 0.98 ×
0.98
Chance of non-rupture = 100 × (risk of no-rupture) years
Chance of rupture = 100 – chance of no-rupture
Calculation: Simple Vs Actual
Simple
Actual
1% annual
risk over 10
years
10
9.6
3 % annual
risk over 20
years
60
46
Updated ISUIA (2003)
<7
<7
Group Group
1
2
Cavernous
0
0
carotid
AC/MC/IC
0
1.5%
Post-P
comm
2.5%
3.4%
7-12
13-24
≥25
0
3%
6.4%
2.6%
14.5%
40%
14.5%
18.4 %
50%
5 year cumulative rupture rate. Wiebers DO et al. Lancet 2003; 362: 103-10
Annual risk of rupture of
unruptured aneurysm
Cavernou
s carotid
AC/MC/IC
Post-P
comm
<7
<7
7-12
13-24
>=25
Group
1
Group
2
0
0
0
0.6
1.3
0
0.3
0.5
3.1
9.7
0.5
0.7
3.1
4
13
Risk of
Intervention Vs natural history
• The Risk of intervention is immediate
• Risk of natural history is distributed over
the life-time
Need to take into out those who
will have a good outcome
following rupture
Life table
• Life-expectancy tables for 2001-2003
• Constructed abridged life-tables
Look-up tables
• ‘Actuarial-type’ table
• Gender specific
• Calculations performed using
Microsoft® Excel® 2003
• Table laid out using Adobe® Illustrator
CS2® and Adobe® InDesign CS2®
‘Hope’ calculator
• Life-time risk of rupture of unruptured
aneurysms
• Effect of intervention on the lifeexpectancy
• Software developed with Macromedia®
Flash 8®
• Both Windows and Mac compatible
55 year old male with sah with an incidental 5 mm Acomm Aneurysm
A 50 year old female with 8 mm rt. PICA aneurysm
A 45 year lady with 8 mm MCA aneurysm
A 60 year male with 13 mm basilar artery aneurysm
Acknowledgements
• Mr Leggate, Mr King
• Mr Hutchinson, Dr Laitt
• Mr West, Mr Richardson, Miss Pickett, Dr
Hughes, Dr Herdwardkar
Acknowledgements
Mr Kirkpatrick, Mr Laing
Professor Mendelow, Mr Mitchell
Professor Harbaugh (Penn State)
Professor Wiebers (Mayo Clinic)
Professor Tamargo (Johns Hopkins)
Questions?