thesis
Improving the diagnostic strategy of pulmonary embolism
- Publication date
- 15 December 2006
- Publisher
- Pulmonary embolism is a common clinical disorder that is associated with high morbidity
and mortality if untreated. In the only randomized study comparing anticoagulant therapy
with no treatment in patients with pulmonary embolism, 26% of untreated patients had
a fatal embolic event and another 26% developed nonfatal recurrent emboli1. With a course
of anticoagulant treatment, the recurrence rate of thromboembolic events decreases to
approximately 2% to 9% over 3 to 6 months2, 3. However, anticoagulation always carries a risk
for bleeding (annual rate of major bleeding, 7%)4, 5. To avoid unnecessary anticoagulant
therapy, it is therefore important to rapidly confirm or exclude pulmonary embolism in
patients who present with suspicion of the disorder.
Diagnosing or excluding pulmonary embolism on the basis of clinical manifestations alone
is difficult because such manifestations are nonspecific6. Approximately 25% of patients
with suspected pulmonary embolism have the disease confirmed by objective testing7-9.
The goal of the first diagnostic strategies introduced was to confirm rather than exclude the
presence of pulmonary emboli. The more recently evaluated diagnostic approaches have
focused on identifying patients who probably do not have pulmonary embolism and therefore
do not require anticoagulant therapy. Various invasive and noninvasive diagnostic methods
have been advocated for excluding the disease.
We performed a systematic review of the literature to evaluate diagnostic strategies
designed to exclude pulmonary embolism. Our objective was to investigate whether clinical
outcome evaluation properly documented the safety of withholding anticoagulant
treatment in patients in whom pulmonary embolism was excluded according to a given
diagnostic strategy. We assessed the accuracy of the various diagnostic strategies by
examining the number of symptomatic thromboembolic events (deep venous thrombosis or
pulmonary embolism) that occurred without anticoagulant treatment during a follow-up period
of at least 3 months. Studies were grouped according to the number of rounds of diagnostic
testing performed before pulmonary embolism was ruled out.