SPC365

A comparative analysis of the diagnostic performances of four clinical probability models to rule out pulmonary embolism

Session: CO 19- Hipertensão Pulmonar
Speaker: Beatriz Valente Silva

Congress: CPC 2021
Topic: F. Valvular, Myocardial, Pericardial, Pulmonary, Congenital Heart Disease
Theme: 21. Pulmonary Circulation, Pulmonary Embolism, Right Heart Failure
Subtheme: 21.3 Pulmonary Circulation, Pulmonary Embolism, Right Heart Failure – Diagnostic Methods
Session Type: Comunicações Orais
FP Number: ---
Authors: Beatriz Silva ; Cláudia Jorge; Joana Rigueira; Tiago Rodrigues; Miguel Nobre Menezes; Rui Plácido; Nelson Cunha; Pedro Silvério António; Sara Couto Pereira; Joana Brito; Pedro Alves da Silva; Margarida Martins; Beatriz Garcia; Catarina Oliveira; Inês Aguiar Ricardo; Fausto j. Pinto

<p style="text-align:justify"><span style="font-size:11pt"><span style="font-family:'Times New Roman'"><span style="color:#000000"><strong>Background</strong></span></span></span><span style="font-size:11pt"><span style="font-family:'Times New Roman'"><span style="color:#000000">:&nbsp;Ruling out pulmonary embolism (PE) through a combination of clinical assessment and Ddimer is crucial to avoid excessive computed tomography pulmonary angiography (CTPA), and different algorithms should be considered as an alternative to the fixed cutoff to achieve that goal.</span></span></span></p>

<p style="text-align:justify"><span style="font-size:11pt"><span style="font-family:'Times New Roman'"><span style="color:#000000"><strong>Purpose</strong></span></span></span><span style="font-size:11pt"><span style="font-family:'Times New Roman'"><span style="color:#000000">:&nbsp;To compare sensitivity, specificity, and reduction in CTPA requests of 4 algorithms to rule out PE: fixed Ddimer cutoff, age-adjusted, YEARS and PEGeD.</span></span></span></p>

<p style="text-align:justify"><span style="font-size:11pt"><span style="font-family:'Times New Roman'"><span style="color:#000000"><strong>Methods</strong></span></span></span><span style="font-size:11pt"><span style="font-family:'Times New Roman'"><span style="color:#000000">:&nbsp;Retrospective study of consecutive outpatients who presented to the emergency department and underwent CTPA for PE suspicion from April 2019 to May 2020. The clinical-decision algorithms were retrospectively applied.</span></span></span></p>

<p style="text-align:justify"><span style="font-size:11pt"><span style="font-family:'Times New Roman'"><span style="color:#000000">In fixed and age-adjusted cut-off, high probability patients are directly selected for CTPA. In fixed cutoff, low to moderate probability patients undergo CTPA if Ddimer &ge;500&micro;g/L. In age-adjusted cutoff, low to moderate probability patients perform CTPA if Ddimer &ge;500&micro;g/L in patients who are 50 years of age or younger, and if Ddimer level was more than 10 times the patient&rsquo;s age in patients who are older than 50 years.&nbsp;</span></span></span></p>

<p style="text-align:justify"><span style="font-size:11pt"><span style="font-family:'Times New Roman'"><span style="color:#000000">YEARS includes 3 items (signs of deep vein thrombosis, haemoptysis and whether PE is the most likely diagnosis): patients without any YEARS items and Ddimer &ge;1000ng/mL or with &ge;1 items and Ddimer 500ng/mL perform CTPA. In the PEGeD, patients with high&nbsp;clinical probability or with&nbsp;intermediate and Ddimers &gt;500&micro;g/L or low probability and Ddimer &gt;1000 &micro;g/L are selected for CTPA.</span></span></span></p>

<p style="text-align:justify"><span style="font-size:11pt"><span style="font-family:'Times New Roman'"><span style="color:#000000"><strong>Results</strong></span></span></span><span style="font-size:11pt"><span style="font-family:'Times New Roman'"><span style="color:#000000">: We selected 571 patients and PE was confirmed by CTPA in 172 patients. Compared with a fixed Ddimer cutoff, age-adjusted was associated with a significant increase of specificity (p&lt;0.001), correctly avoiding 38 CTPAs, without losing sensitivity.&nbsp;YEARS and PEGED resulted in a marked increase in specificity, compared to the fixed cutoff, but with impairment of sensitivity (p&lt;0.001). PEGeD had the worst sensitivity, associated with 13 more false negatives (FN)&nbsp;than the fixed cutoff.</span></span></span></p>

<p style="text-align:justify"><span style="font-size:11pt"><span style="font-family:'Times New Roman'"><span style="color:#000000">Despite the lack of difference between PEGed and YEARS strategies regarding sensitivity, PEGED had significantly higher specificity (p&lt;0.001) and allowed to correctly avoid a higher number of CTPA (95 vs 85), compared to the fixed cutoff.&nbsp;</span></span></span></p>

<p style="text-align:justify"><span style="font-size:11pt"><span style="font-family:'Times New Roman'"><span style="color:#000000">Results are summarized in table 1 and the AUC for each algorithm is shown in figure 1.</span></span></span></p>

<p><span style="font-size:11pt"><span style="font-family:'Times New Roman'"><span style="color:#000000"><strong>Conclusion</strong></span></span></span><span style="font-size:11pt"><span style="font-family:'Times New Roman'"><span style="color:#000000">:&nbsp;Compared to fixed d-dimer cutoff, all algorithms were associated with increased specificity. The age-adjusted cutoff was the only that was not associated with a significant decrease in sensitivity when compared to fixed cutoff, allowing to safely reduce the need to perform CTPA.</span></span></span></p>