Diagnosing acute pulmonary embolism - Effect of chronic obstructive pulmonary disease on the performance of D-dimer testing, ventilation/perfusion scintigraphy, spiral computed tomographic angiography, and conventional angiography

In patients with chronic obstructive pulmonary disease (COPD), differentiat ing a pulmonary embolism (PE) from an exacerbation of COPD can be difficult , since clinical signs and symptoms of the two conditions overlap. Developm ent of reliable noninvasive or minimally invasive techniques for the diagno sis of PE is, especially in these patients, necessary. In this study we ass essed the effect of COPD on the accuracy of the clinical probability estima te (CPE), spiral computed tomographic angiography (SCTA), D-dimer analysis, ventilation perfusion (V) over dot/(Q) over dot) scintigraphy, and pulmona ry angiography for the diagnosis of PE. From May 1997 through March 1998, 6 27 consecutive patients with suspected PE were investigated in six teaching hospitals. In these patients, D-dimer testing, CPE, (V) over dot/(Q) over dot scintigraphy, and SCTA and/or pulmonary angiography were performed acco rding to a strict diagnostic protocol. The patients were also independently categorized as having COPD or not. A disagnosis of COPD was established in 91 patients (15%). The prevalence of PE was similar in patients with and w ithout COPD (29% and 31%, respectively), notwithstanding the larger proport ion of nondiagnostic (V) over dot/(Q) over dot scan results in patients wit h COPD (46% versus 21%, p < 0.001). The distribution of CPEs, diagnostic va lue of the D-dimer assay and SCTA, and reproducibility of pulmonary angiogr aphy were comparable among patients with and without COPD. The presence of COPD does not affect the diagnostic performance of CPE, D-dimer testing, SC TA, or pulmonary angiography. Furthermore, although more nondiagnostic (V) over dot/(Q) over dot scan results can be expected in the presence of COPD, (V) over dot/(Q) over dot scintigraphy remains a valuable screening test i n patients with COPD.