Ashton HA, Buxton MJ, Day NE, et al. The Multicentre Aneurysm Screening Study (MASS) into the effect of abdominal aortic aneurysm screening on mortality in men: a randomized controlled trial. Lancet 2002; 360:1531-1539.
* PRACTICE RECOMMENDATIONS
Screening for abdominal aortic aneurysm (AAA) in men over age 65 years reduced their mortality related to AAA, but did not affect overall mortality. Therefore, population-based screening for AAA cannot be recommended.
Emergency surgery following ruptured AAA is seldom successful, though surgical intervention before rupture occurs may prevent significant morbidity and mortality. Ultrasound can often detect AAAs at a size when rupture is still unlikely to occur, providing an opportunity for early intervention.
* POPULATION STUDIED
More than 70,000 men, aged 65 years and over, were recruited from 4 outpatient health centers in the United Kingdom. Patients were excluded if they had a previous AAA repair, terminal illness, or other serious health problem. Of the 67,800 men who qualified, 33,839 men were randomly chosen to receive an invitation for an abdominal ultrasound to screen for AAA, and the remaining 33,961 men acted as controls.
* STUDY DESIGN AND VALIDITY
Patients were randomized in a concealed fashion to receive abdominal ultrasound to screen for AAA or to receive routine health care. Those among the scanned group whose aorta measured 3 cm or greater were assigned to follow-up: yearly scans for an aortic diameter of 3.0-4.4 cm, quarterly scans for a diameter of 4.5-5.4 cm, or referral to surgery for diameters of 5.5 cm or greater. Follow-up ranged from 3 to 5 years.
Mortality was assessed through review of death certificates by an independent party, and additional information was collected to confirm cause of death. Quality of life was measured with 4 standardized scales. Quality assurance of ultrasound scanning was monitored throughout the study.
* OUTCOMES MEASURED
The primary outcome measured was death related to AAA. Other outcomes measured included all-cause mortality, frequency of ruptured AAA, 30-day surgical mortality, and the effect of screening and surgery on quality of life.
The group that was scanned had a significantly lower rate of aneurysm-related mortality (0.19%) than the group not scanned (0.33%), yielding a relative risk reduction of 42% (P=.0002, number needed to screen=710). However, there was no difference in all-cause mortality between the 2 groups, likely due to the relatively low prevalence of AAA.
Death rates from surgery did not differ much between the groups. Quality of life--including anxiety, depression, and perception of health status--did not differ between men who had positive scans and those who had negative scans. Cost-effectiveness data were gathered but have not yet been published.
David Fisher, MD, MPH, and Richard Lord, MD, Department of Family and Community Medicine, Wake Forest University, Winston-Salem, NC. E-mail: firstname.lastname@example.org.
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