AAA screening

The new NHS screening programme for AAA is being rolled out. The information for patients and drs states that screening 'could reduce the rate of premature death from ruptured AAA by up to 50%', but it fails to mention what this means in absolute terms. We covered this on the Hot Topics last year, see below. We believe patients and doctors should be aware that this 50% 'relative risk' reduction in absolute terms is from 0.87% to 0.46%, and that despite 67,000 people being included in the original study there was no reduction in overall mortality.

A screening programme for AAA for men aged 65 (www.aaa.screening.nhs.uk) is being introduced gradually across England, it started in 2009 and it is anticipated it will be nationwide by 2013. In Scotland it will be phased in between 20011 and 2013, and details in Wales and NI have yet to be formalised. The programme is based closely on the protocol of the The Multicentre Aneurysm Screening Study (BMJ2009;338:b2307)    

·         67,000 men were recruited from 4 UK centres aged 65-74 and randomised to be invited for screening, or not.
·         Overall, screening halved (RRR of 48%) the risk of AAA related deaths
·         However, the absolute differences are very small

o   155 AAA deaths in the invited group (0.46%) compared with 286 (0.87%) in the control group

·         There was no difference in overall mortality and the mean age of death (75) was the same in the invited and control groups

Should I have the test doc?
The NHS screening programme has produced a leaflet for doctors explaining how the process will work (www.aaa.screening.nhs.uk). We can inform our patients that of every 1,000 men invited:

• 960 will have a normal scan
• 35 will have a small aneurysm, which will need regular surveillance and monitoring (including more aggressive CV risk factor reduction and treatment of hypertension)
• 5 in 1,000 will have a large aneurysm and be offered surgery

 What about women?

The screening programme is looking at asymptomatic men aged 65. Women who are at high risk (e.g. due to family history, or multiple risk factors, or both) may of course be offered a routine scan outside of the screening programme. Men over 65 can self-refer to be screened.

 

AAA Screening: NB Practice Points

·         Screening has started, and men aged over 65 will be invited for a scan

·         The MASS study shows that screening for AAA will halve the risk of a AAA related deaths in men, from approx. 1% to 0.5%.

·         Women at high risk will need to have a scan arranged by you independently; they are not included in the screening programme