Results: Overall, CT angiograms were negative for PE in 1806 (90.16%) of 2003 patients. CT angiograms were positive for PE in 197 (9.84%) of 2003 patients; 6.36% were Emergency Department patients, and 13.46% were inpatients. Of the 197 patients with CT angiograms positive for PE, 192 (97.46%) had one or more risk factors, of which age of 65 years or older (69.04%) was the most common. Of the 1806 patients with CT angiograms negative for PE, 520 (28.79%) had no risk factors. The sensitivity and negative predictive value of risk factor assessment in all patients were 97.46% and 99.05%, respectively. All risk factors, except sex, were significant in the multivariate logistic regression (P less than .031).
Conclusion: In the setting of no risk factors, it is extraordinarily unlikely (0.95% chance) to have a CT angiogram positive for PE. This selectivity and triage step should help reduce current costs and radiation exposure to patients.
You can safely avoid an imaging study if none of the risk factors are present. You have to be female to qualify, it seems.
CME at Medscape.