Outcomes following a negative computed tomography pulmonary angiography according to pulmonary embolism prevalence: a meta‐analysis of the management outcome studies

Abstract

Background Outcome studies have reported the safety of computed tomographic pulmonary angiography (CTPA) as a stand-alone imaging technique to rule out pulmonary embolism (PE). Whether this can be applied to all clinical probabilities remains controversial. Objectives We performed a meta-analysis to determine the proportion of patients with venous thromboembolic events (VTE) despite a negative CTPA according to pretest PE prevalence. Methods We searched MEDLINE, EMBASE and the Cochrane Library (January 1990 to May 2017) for outcome studies recruiting patients with suspected PE using CTPA as a diagnostic strategy. The primary outcome was the cumulative occurrence of VTE at 3 months following a negative CTPA. Results Twenty-two different studies were identified. VTE was confirmed in 2.4% of patients (95% CI, 1.3-3.8%) either at the time of the index event or in the 3 months follow-up. Subgroup analyses suggested that the cumulative occurrence of VTE was related to pretest prevalence of PE, as VTE occurred in 1.8% (95% CI, 0.5-3.7%), 1.4% (95% CI, 0.7-2.3%), 1.0% (95% CI, 0.5-1.8%) and 8.1% (95% CI, 3.5-14.5%) of subgroups of patients with a PE prevalence < 20%, 20-29%, 30-39% and ≥ 40%, respectively. This was further confirmed using meta-regression analysis. Conclusions The negative predictive value of CTPA for VTE varies according to pretest prevalence of PE, and is likely to be insufficient to safely rule out VTE as a stand-alone diagnostic test amongst patients at the highest pretest probability of VTE. Prospective studies are required to validate the appropriate diagnostic algorithm for this subgroup of patients.

Weight-Adjusted Contrast Administration in the Computed Tomography Evaluation of Pulmonary Embolism

“…Although an acceptable definitive positive CTPA rate is yet to be established, a yield of 10% or less may reflect overuse of CTPA, where the test becomes more of a screening tool rather than a diagnostic tool [21]. CTPA has been shown to have a high negative predictive value ranging from 98.6% to 99.9%, requiring no additional imaging for patients with suspected acute PE with a negative CTPA [22]. For this reason, CTPA is widely considered as a stand-alone imaging test for suspected acute PE.…”

Prevalence of Pulmonary Embolism in Patients Presenting With Syncope

“…Finally, the presenting symptoms, patient characteristics, and rationale for obtaining the CTA were not discussed in most of the included trials. While CTA of chest with contrast possesses high sensitivity and specificity for diagnosis of PE in low pretest probability patients, test characteristics decrease in patients with high pretest probability . Discordance among radiologists for diagnosis of PE can also be severe, with poor interreader reliability …”