D-dimer laboratory testing may not be as accurate as a combination of heart rate, respiratory rate, oxygen saturation, limb swelling, recent surgical history, current cancer diagnosis, limb immobility, presence of central line, and prior venous thromboembolism event in predicting the presence of a pulmonary embolism (PE) in pediatric patients, according to a study published in the Archives of Disease in Childhood.
A retrospective review of clinical data from the previous 11 years was conducted using the charts of 543 patients between the ages of 5 and 17 to determine the clinical characteristics of patients evaluated for PE with D-dimer testing, computed tomography (CT) angiography and/or ventilation-perfusion (VQ) scan. The objective of the study was to assess the clinical predictors for PE in pediatric patients.
Of the 526 patients in whom D-dimer laboratory testing was ordered, only 34 were found to have a PE (6.4%; 95% CI, 4.3% to 8.7%). The majority of patients evaluated for PE were teenagers (88%) with a mean age of 15 years. Female to male ratio for PE testing was 2:1, but was near 1:1 for confirmed PE diagnosis.
Patients were most often evaluated for PE in the emergency department (ED), and being evaluated in the ED was associated with a lower probability of a PE.
Study results found children with a PE diagnosis presented most frequently with tachycardia, tachypnea, lower oxygen saturation, and leg swelling. In addition, the review of data found an additional 5 patient histories frequently associated with a PE diagnosis, including a history of surgery, presence of a central line, limb immobility, prior history of a PE or deep vein thrombosis, and a history of/current cancer diagnosis.
Investigators identified the combination of the following 9 components as a useful probability assessment tool for patients with a suspected PE: heart rate <100 beats/min, respiratory rate <22 breaths/min, oxygen saturation (SaO2%) >94%, no limb swelling and no recent surgery, active cancer, limb immobility, central line in place, or prior venous thromboembolism. The sensitivity and specificity of these criteria are 92.2% (95% CI, 81.1-97.8%) and 44% (95% CI, 39.5-38.4%). The absence of positive results in any of the 9 criteria in addition to a negative D-dimer test was found to have a sensitivity of 100% (95% CI, 89-100%) and specificity of 39% (95% CI, 34.5-43.3%).
Therefore, clinicians can use these 9 clinical variables to guide diagnostic decisions, however prospective validation research is needed before these criteria can become established guidelines.
Kanis J, Pike J, Hall CL, Kline JA. Clinical characteristics of children evaluated for suspected pulmonary embolism with D-dimer testing [published online November 8, 2017]. Arch Dis Child. doi:10.1136/archdischild-2017-313317