05 Mar Screening For Abdominal Aortic Aneurysms May Have Benefits and Harms
MedicalResearch.com Interview with:
Minna Johansson, PhD student
Department of Public Health and Community Medicine, Institute of Medicine
The Sahlgrenska Academy, University of Gothenburg, Gothenburg, Research Unit and Section for General Practice, Vänersborg, Sweden
Medical Research: What is the background for this study? What are the main findings?
Response: The decision to introduce screening for abdominal aortic aneurysms (AAA) was based on four randomised controlled trials from the 1980s and 1990s that showed a 50% relative risk reduction in aneurysm-related mortality. Over the last 15 years Sweden, the UK and the USA have introduced AAA screening programmes.
However, abdominal aortic aneurysms screening does not only have intended benefits but also unintended harms. The most important harm is overdiganosis; i.e. the overdetection of aneurysms that would not have caused symptoms in that man´s remaining life, nor been the cause of his death. In this study, we estimate that 176 of every 10,000 men invited to screening are overdiagnosed as a consequence of screening. These men are unnecessarily turned into patients and may experience appreciable anxiety throughout their remaining lives. Moreover, 37 of these men unnecessarily have preventive surgery and 1.6 of them die as a consequence.
Furthermore, a recent drop in abdominal aortic aneurysms prevalence by over 70% reduces the potential benefits of AAA screening. Unfortunately, the harms are not likely to be reduced by the same rate, thus leading to a worsened benefit:harm ratio. This means that the benefit:harm ratio is likely to be worse in current screening programmes than in the trials on which they were based.
Additionally, it has been proposed to lower the cut-off for the abdominal aortic aneurysms-diagnosis from 30 to 25 mm. Our estimates show that such a change of definition would increase the rate of overdiganosis substantially and further worsen the benefit:harm ratio of abdominal aortic aneurysms screening.
Medical Research: What should clinicians and patients take away from your report?
Response: Clinicians/screening programmes should inform potential screening participants on both benefits and harms of AAA screening and screening invitees should understand that non-participation might be an equally rational choice as participation. But more importantly, we argue that abdominal aortic aneurysms screening programmes should be revisited because of reduced benefits in modern populations and because data suggest considerable harm.
Medical Research: What recommendations do you have for future research as a result of this study?
Response: We need studies on the magnitude of both benefits and harms caused by current abdominal aortic aneurysms screening programmes in populations with a low AAA prevalence. Particularly surveys on psychosocial consequences of overdiagnosis are needed.
Johansson, A. Hansson, J. Brodersen. Estimating overdiagnosis in screening for abdominal aortic aneurysm: could a change in smoking habits and lowered aortic diameter tip the balance of screening towards harm? BMJ, 2015; 350 (mar03 13): h825 DOI: 10.1136/bmj.h825
MedicalResearch.com Interview with, Minna Johansson, PhD student, Department of Public Health and Community Medicine, Institute of Medicine (2015). Screening For Abdominal Aortic Aneurysms May Have Benefits and Harms