Pulmonary embolism is a potentially fatal disease in which early recognition and institution of anticoagulant treatment can prevent mortality. The diagnostic tools available to establish whether a... Show morePulmonary embolism is a potentially fatal disease in which early recognition and institution of anticoagulant treatment can prevent mortality. The diagnostic tools available to establish whether a patient has a pulmonary embolism were limited to pulmonary angiography and ventilation-perfusion scintigraphy. Both tests have considerable limitations. Helical CT evolved as a new technique in diagnosing PE and gained widespread interest but has been implemented rapidly, without appropriate assessment in clinical practice. The Christopher-study was performed to investigate whether a dichotomization of the Wells clinical decision rule, classifying patients into __PE unlikely__ and __PE likely__ in combination with a D-dimer test is safe to rule out pulmonary embolism in patients with a clinical suspicion. Furthermore, the study was designed to investigate whether helical CT is safe to rule out PE without performing any additional diagnostic tests. In patients in whom PE was excluded by a clinical decision rule indicating __PE unlikely__ combined with a negative D-dimer, during three months of follow-up venous thrombo-embolism was diagnosed in 5 out of 1028 untreated patients (0.5%, 95%CI: 0.2-1.1). In patients in whom CT had ruled out PE, during three months follow-up 18 of 1446 untreated patients experienced a venous thrombo-embolic event (1.3%, 95%CI: 0.7-2.0). In conclusion, the Christopher-study demonstrates that a simple diagnostic algorithm consisting of a dichotomised clinical decision rule, D-dimer and helical CT can guide treatment decisions with a low risk of subsequent venous thrombo-embolism. Show less
