Positive predictive value of clinical suspicion of abdominal aortic aneurysm. Implications for efficient use of abdominal ultrasonography.

Although selective screening for an abdominal aortic aneurysm (AAA) by abdominal palpation aimed at detecting AAAs has engendered considerable support, no population-based data pertaining to the positive predictive value (PPV) of the clinical assessment of AAAs in routine clinical practice are available. Therefore, we used the unique resources of the Rochester (Minn) Epidemiology Project and the Mayo Clinic computerized abdominal ultrasonography database to identify all residents of Olmsted County, Minnesota,who underwent ultrasound examination for a clinically suspected AAA between November 1, 1985, and October 31, 1987. Of 116 residents who were suspected of having an AAA on abdominal palpation and were referred for an ultrasound examination for confirmation, 17 patients had a 3.5-cm or greater AAA by ultrasound examination (PPV = 14.7%). The probability of AAA by ultrasound examination (PPV = 14.7%). The probability of AAA documentation by ultrasound examination given clinical suspicion of an AAA was associated with higher body mass index, older age,and presence of other macrovascular disease. In 17 patients aged 70 years or younger, without other macrovascular disease and with body mass index of 24 or less, only 1 had an AAA of 3.5 cm or greater (PPV = 6%), while 10 of 20 patients aged 70 years or older, with macrovascular disease,and with body mass index greater than 24 had an AAA of 3.5 cm or greater (PPV = 50%). These population-based data that highlight the poor PPV of the clinical assessment for AAAs indicate that abdominal palpation aimed at detecting AAAs as part of a periodic health examination may lead to a much higher rate of false-positive results than indicated by previous referral-based data. Further research is needed to identify patient subgroups in whom abdominal palpation for detection of AAAs will be cost-effective with respect to reduction in AAA mortality.