BACKGROUND AND AIMS
Pulmonary embolism (PE) is associated with high morbidity and mortality and often has a nonspecific clinical presentation; thus, prognostic assessment is important for the management of patients with PE. The use of diagnostic testing to reduce the risk of missing a potentially life-threatening diagnosis increases both the cost of care and the use of medical resources. Various score systems exist to evaluate the probability of PE, which can also be used for risk stratification to obtain the most accurate diagnosis. The aim of our study was to review the evidence for existing prognostic models in acute PE and determine their validity and usefulness for predicting patient outcomes. We also determined the accuracy of an age-adjusted D-dimer threshold to detect PE.
MATERIALS AND METHODS
The study involved the retrospective application of an age-dependent D-dimer cut-off (age/100 in patients aged >50 years) in 659 consecutive patients, both in and outpatients, aged ≥18 years who had undergone CT pulmonary angiogram for suspected PE according to the European Society of Cardiology (ESC) guidelines. We included individuals who presented to an emergency department with a suspicion of PE and who were then referred for objective testing; all participants included were capable of providing informed consent. This study was performed in three emergency departments in Hungary between January 2016 and September 2017. We retrospectively collected information regarding symptoms (dyspnoea, unilateral leg swelling, and haemoptysis), vital signs, and medical and social history (cancer, recent surgery, medication, history of deep vein thrombosis or PE, and chronic obstructive pulmonary disease). We calculated test characteristics, including sensitivity and specificity. We applied three different D-dimer approaches to the low and moderate-probability patients.
The primary outcome was exclusion of PE with each D-dimer approach, while the secondary objective was to estimate the negative predictive value for each rule. Data were analysed using SPSS 20.0 statistical software (SPSS Inc., Chicago, Illinois, USA) and a chi-squared test, Independent Samples T Test, analysis of variance (ANOVA), and correlation interpretation were performed; p values <0.05 were considered statistically significant.
In the 659 cases (407 women and 252 men), a total of 105 D-dimer assays, 51 CT angiograms, and 212 chest X-ray examinations were carried out redundantly; if these procedures were not carried out, it could have saved money for the hospitals and reduced radiation exposure for patients. The age-adjusted D-dimer threshold was more specific (70% versus 60%) but less sensitive (95% versus 98%) than risk stratification. The sensitivity of the combined technique (risk stratification and age-adjusted D-dimer test) was 100%.
Our study showed that Geneva score (which was calculated from the patients’ complaints, medical history, and physical examination) had the closest correlation with the true diagnosis. An age-adjusted D-dimer limit has the potential to reduce the need for diagnostic imaging and is more accurate than the standard threshold of 500 ng/dL. The combination of risk stratification and age-adjusted D-dimer can be used to safety diagnose PE. Finally, we can conclude that risk evaluation in acute PE is indispensable and the appropriate use of guidelines results in lower healthcare costs. Our data support the use of age-adjustment and perhaps adjustment for other factors also seen in patients evaluated for PE.