According to a study published in The Lancet in 2002, screening for abdominal aortic aneurysms (AAAs) using ultrasound scans (USS) reduces incidence of rupture by 49% and aneurysm-related mortality by 42%. However, a cost-effectiveness analysis reveals that the cost of a quality-adjusted life year (QALY) is £36,000 for the first year. Therefore, anything that can be done to bring costs down to an acceptable level is a good move. Mr Michael Heng, Surgical Research Fellow in the Academic Vascular Unit at Hull Royal Infirmary, presented interim results from a prospective study into AAA self-examination. However, reactions to the presentation were not all supportive.
“A lot of the surgeons there have strong opinions about the screening programme. The first thing to say is that our study is nothing to do with the National Ultrasound Screening Programme; we’re fully supportive of that. It’s the gold standard,” Heng told Vascular News. “Other possibilities notwithstanding, we’re trying to confirm firstly if it’s possible to detect AAAs through self-examination. After that we’re looking at maybe getting to those people who would fall outside of the [proposed] national programme (such as women or younger men) or those who can’t make it to the screening centres. But a lot of people in the audience were discouraged that we were looking at other forms of AAA detection.” The truth is that non-attendance of USS is roughly 15-37%, which leaves a large proportion of the target population – men aged over 65 years old – untested.
The idea of self-examination is not new – people are already encouraged to feel their breasts or testicles for tumours. Study co-author Professor Peter McCollum told Vascular News: “I’ve done a lot of aneurysm surgery, and I realised that many of the patients could feel their aneurysms… the secret is for them to know how to palpate the tummy.” The aim of the study therefore was i) to assess the sensitivity and specificity of self-examination in the detection of clinically significant (>5cm) AAAs in the community; and ii) to assess the psychological consequences of screening for AAAs by self-examination. The reason for concentrating on such large aneurysms is that not only are they easier to feel above that size but also, according to previous studies it is relatively safe to wait until they reach 5.5cm. “Not every aneurysm will rupture,” added McCollum.
In total, 1,234 patients, median age 72, took part in the initial study. They were sent a leaflet describing the abdominal palpation technique to use, and were asked to feel themselves and, if possible, to get a partner or friend to check as well. All participants then had an abdominal USS to determine aortic diameter. The psychological consequences were assessed on three occasions using a questionnaire and the Hospital Anxiety and Depression (HAD) scale at the time of examination, at the USS and one month later.
According to the USS results, 15 people had AAAs above 5cm – 10 of whom positively identified them through self examination – giving a sensitivity in the detection of AAAs of 67%. Of the 1,075 people without AAAs above 5cm, 891 correctly said they had no aneurysm, giving a specificity of 83%. Positive predictive value of the test was 5.1% and negative predictive value was 99%. With a second person examining as well, sensitivity rose to 80% while specificity fell to 77%. Positive predictive value was 4.4% and negative predictive value was still 99%.
In terms of the psychological effect, using the HAD scale, mean depression at the time of self-examination was 3.42, falling to 3.22 one month later. For the same time periods, anxiety fell from 4.17 to 3.89. “There were no adverse levels of anxiety or depression in the test population,” Heng confirmed. “And the difference with this test compared to other self-examinations is that if there is a positive result it is not followed by an invasive test – it’s followed by a USS, which is quick and easy.”
The data to date show that screening for AAAs using self-examination or tandem second person examination is effective for clinically significant AAAs. “The study is ongoing, and to be properly powered we need to recruit 9,000 people,” explained Heng. He estimates that this will be possible within two years, now that they have secured funding from a local charity – Humberside Charitable Health Trust.
So while the establishment might have reservations about self-examination in this respect, the researchers are keen to stress that it is as an adjunct to the national screening programme, and not a substitute. “The national programme has been a long time in coming,” Heng observed. “However, I think it will come in, it’s just a matter of time. In the meantime we should investigate other forms of detection.”