The DiPEP study: an observational study of the diagnostic accuracy of clinical assessment, D-dimer and chest x-ray for suspected pulmonary embolism in pregnancy and postpartum

Objective To identify clinical features associated with pulmonary embolism (PE) diagnosis and determine the accuracy of decision rules and D-dimer for diagnosing suspected PE in pregnant/postpartum women Design Observational cohort study augmented with additional cases. Setting Emergency departments and maternity units at eleven prospectively recruiting sites and maternity units in the United Kingdom Obstetric Surveillance System (UKOSS) Population 324 pregnant/postpartum women with suspected PE and 198 pregnant/postpartum women with diagnosed PE Methods We recorded clinical features, elements of clinical decision rules, D-dimer measurements, imaging results, treatments and adverse outcomes up to 30 days Main outcome measures Women were classified as having PE on the basis of imaging, treatment and adverse outcomes by assessors blind to clinical features and D-dimer. Primary analysis was limited to women with conclusive imaging to avoid work-up bias. Secondary analyses included women with clinically diagnosed or ruled out PE. Results The only clinical features associated with PE on multivariate analysis were age (odds ratio 1.06; 95% confidence interval 1.01-1.11), previous thrombosis (3.07; 1.05-8.99), family history of thrombosis (0.35; 0.14-0.90), temperature (2.22; 1.26-3.91), systolic blood pressure (0.96; 0.93-0.99), oxygen saturation (0.87; 0.78-0.97) and PE-related chest x-ray abnormality (13.4; 1.39-130.2). Clinical decision rules had areas under the receiver-operator characteristic curve ranging from 0.577 to 0.732 and no clinically useful threshold for decision-making. Sensitivities and specificities of D-dimer were 88.4% and 8.8% using a standard threshold and 69.8% and 32.8% using a pregnancy-specific threshold. Conclusions Clinical decision rules and D-dimer should not be used to select pregnant or postpartum women with suspected PE for further investigation. Clinical features and chest x-ray appearances may have counter-intuitive associations with PE in this context. Tweetable abstract Clinical decision rules and D-dimer are not helpful for diagnosing pregnant/postpartum women with suspected PE