Effects of age on the performance of common diagnostic tests for pulmonary embolism

Diagnosis and management of pulmonary embolism in the elderly

“…As mentioned earlier, the main limitation of V/Q scan is a significant proportion of nondiagnostic results, which increases with age (from 32% in patients b 40 years to 58% in those N80 years) [33] due to a higher prevalence of cardio-pulmonary comorbidities and chest X-ray abnormalities [45]. V/Q scan results thus need to be interpreted in conjunction with clinical probability and CUS, the latter sometimes being repeated at a week's interval in order to safely exclude PE [46].…”

“…Interestingly, data from two large prospective management outcome studies enrolling more than 1000 consecutive patients with suspected PE show a higher yield of CUS in elderly patients compared to younger patients. Proximal DVT was indeed found in 7% of patients b 40 years and in 25% of those N80 years, corresponding to a NNT of only 4 in the older group to rule in one PE without further imaging [33]. It thus seems useful to perform CUS in elderly patients with severe renal failure as the first imaging test.…”

“…This means that the probability of having a negative test result is reduced and hence the number of patients needed to test to exclude one PE (NNT) without further testing is higher. Indeed, whereas PE can be ruled out in the presence of non-high clinical probability and negative D-dimers in one out of 3 outpatients presenting to the emergency room with suspected PE [28], it can be excluded in only one out of 9 patients with cancer [32] and one out of 20 patients N 80 years [33]. As current diagnostic strategies for PE include imaging (most often CTPA) in patients with positive D-dimers, lack of specificity of D-dimers in the elderly leads to a high proportion of these patients undergoing CTPA.…”

Pulmonary embolism: an unsuspected killer

“…The specificity of D dimer was found to be 67% in patients younger than 40, but only 10% in patients age 80 and older. In addition, the number of nondiagnostic V/Q scans increased from 32% to 58% in these same age groups [72]. There is no single diagnostic test that is ideal for the diagnosis of PE in elderly patients.…”

DVT: current approaches to diagnosis and treatment

“…While absence of D-dimer suggests absence of thrombus, many other physiological processes can lead to activation of the fibrinolysis pathway and hence to false elevation of D-dimer. This is important in older people in whom multiple co-morbidities are common; in one study, 9 specificity of ELISA D-dimer in patients with suspected PE aged under 40 was 67 per cent, whereas in those over 80 specificity was only 10 per cent, prompting the suggestion that the upper limit for normal for the D-dimer range should be higher in older people. Furthermore, timing of D-dimer assay may also be relevant (D-dimer levels fall a few weeks after thrombus formation), as may recent administration of anticoagulation, which may also lead to a fall in Ddimer.…”