Abstract/Text: Overuse of the d-dimer to screen for possible pulmonary embolism (PE) can have negative consequences. This study derives and tests clinical criteria to justify not ordering a d-dimer. The test threshold was estimated at 1.8% using the method of Pauker and Kassirer. The PE rule-out criteria were derived from logistic regression analysis with stepwise backward elimination of 21 variables collected on 3148 emergency department patients evaluated for PE at 10 US hospitals. Eight variables were included in a block rule: Age < 50 years, pulse < 100 bpm, SaO(2) > 94%, no unilateral leg swelling, no hemoptysis, no recent trauma or surgery, no prior PE or DVT, no hormone use. The rule was then prospectively tested in a low-risk group (1427 patients from two hospitals initially tested for PE with a d-dimer) and a very low-risk group (convenience sample of 382 patients with chief complaint of dyspnea, PE not suspected). The prevalence of PE was 8% (95% confidence interval: 7-9%) in the low-risk group and 2% (1-4%) in the very low-risk group on longitudinal follow-up. Application of the rule in the low-risk and very low-risk populations yielded sensitivities of 96% and 100% and specificities of 27% and 15%, respectively. The prevalence of PE in those who met the rule criteria was 1.4% (0.5-3.0%) and 0% (0-6.2%), respectively. The derived eight-factor block rule reduced the pretest probability below the test threshold for d-dimer in two validation populations, but the rule's utility was limited by low specificity.

Abstract/Text: BACKGROUND: This study aimed to assess the performance of two prognostic models-the European Society of Cardiology (ESC) model and the simplified Pulmonary Embolism Severity Index (sPESI)-in predicting short-term mortality in patients with pulmonary embolism (PE).
METHODS: We compared the test characteristics of the ESC model and the sPESI for predicting 30-day outcomes in a cohort of 526 patients with objectively confirmed PE. The primary end point of the study was all-cause mortality. The secondary end point included all-cause mortality, nonfatal symptomatic recurrent VTE, or nonfatal major bleeding.
RESULTS: Overall, 40 of 526 patients died (7.6%; 95% CI, 5.3%-9.9%) during the first month of follow-up. The sPESI classified fewer patients as low risk (31% [165 of 526], 95% CI, 27%-35%) compared with the ESC model (39% [207 of 526], 95% CI, 35% to 44%; P < .01). Importantly however, low-risk patients based on the sPESI had no 30-day mortality compared with 3.4% (95% CI, 0.9-5.8) in low-risk patients by the ESC model. The secondary end point occurred in 1.8% of patients in the sPESI low-risk and 5.8% in the ESC low-risk group (difference, 4.0 percentage points; 95% CI, 0.2-7.8). The prognostic ability of the ESC model remained significant in the subgroup of patients at high-risk according to the sPESI model (OR 1.95, 95% CI, 1.41 to 2.71, P < .001).
CONCLUSIONS: Both the sPESI and the ESC model successfully predict 30-day mortality after acute symptomatic PE, but exclusion of an adverse early outcome does not appear to require routine imaging procedures or laboratory biomarker testing.