Just like the HEART score, they have created another simple clinical decision instrument that has face validity (regardless if it is actually proven). This time, it’s for investigating potential PE in pregnancy.
This multicentre, international trial was conducted at 18 hospitals over 5 years. They included pregnant adults who had been referred to the ED or obstetrical ward with suspected PE.
They aimed to determine whether their pregnancy-adapted YEARS algorithm could be used to avoid diagnostic imaging in this at-risk population.
Simply put, the algorithm is as follows:
- Three criteria were assessed in all patients; clinical signs of DVT, haemoptysis, whether PE was thought to be the most likely diagnosis. D-dimer was measured.
- Patients with clinical signs of DVT underwent ultrasound.
- If a patient did not meet any of the three YEARS criteria and the D-dimer was less than 1000ng/ml a diagnosis of PE was considered to be ruled out.
- If a patient had any of the YEARS criteria and the D-Dimer was less than 500ng/ml then PE was ruled out.
- All the remaining patients were referred for CTPA.
The primary outcome was the occurrence of symptomatic DVT or PE within 3 months. (Patients did not undergo routine screening.) Secondary outcome was the proportion of patients where CTPA was not indicated.
About 500 women were included. 20 (4%) of patients had a PE diagnosed at baseline. Only one patient (0.2%) was diagnosed with a DVT in the follow up period. There were no PE’s and no deaths. CTPA was avoided (not indicated) in about 40% of patients. The efficiency of the algorithm was better during the first trimester (65% avoided CTPA).
Gold standard screening tests were not performed to look for subsequent DVT or PE. Much like it is hard to find a fever if you don’t take a temperature, it is hard to find VTE if you are not testing for it. But they reportedly did look if patients had symptoms… which is the practical and ethical approach in this RCT.
It is hard for this study to claim safety regarding mortality as death from PE in pregnancy is reasonably low. It will never be feasible to enrol enough patients in an RCT to asses mortality benefit.
What’s the take home?
Using clinical gestalt (i.e. the 3 YEARS criteria) and a pregnancy adjusted D-dimer is a sensible approach.
Van der Pol LM, Tromeur C, Bistervels IM, et al. Pregnancy-Adapted YEARS Algorithm for Diagnosis of Suspected Pulmonary Embolism. N Engl J Med 2019;380:1139-49. [link to article]