Unruptured Aneurysms

G Narenthiran

L Alakandy

J P Holland

Greater Manchester Neurosciences CentreHope 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 0-25%

• 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

100

98

2

1.96

96.4

100 × 0.98

100 × 0.98 × 0.98

100 × 0.98 × 0.98 × 0.98

100 × (risk of no-rupture) yearsChance of non-rupture =

Chance of rupture = 100 – chance of no-rupture

Annual risk of rupture = 2%

Annual risk of no-rupture = 98%

Calculation: Simple Vs Actual

Simple Actual

1% annual risk over 10

years10 9.6

3 % annual risk over 20

years60 46

Updated ISUIA (2003)< 7 < 7 7-12 13-24 ≥25

Group 1

Group 2

Cavernous carotid

0 0 0 3% 6.4%

AC/MC/IC 0 1.5% 2.6% 14.5% 40%

Post-P comm

2.5% 3.4% 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

< 7 < 7 7-12 13-24 >=25

Group 1

Group 2

Cavernous carotid

0 0 0 0.6 1.3

AC/MC/IC 0 0.3 0.5 3.1 9.7

Post-P comm

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 life-expectancy

• 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 MitchellProfessor Harbaugh (Penn State)

Professor Wiebers (Mayo Clinic)

Professor Tamargo (Johns Hopkins)

Questions?Questions?