Dr Lauren Lim is an advanced trainee in general and acute care medicine in Adelaide, South Australia. She has a special interest in medical education. She currently works as the Medical Education Registrar at the Royal Adelaide Hospital and is a clinical associate lecturer at the University of Adelaide.
Use Of Clinical Decision Rules In Predicting Outcomes For Patients With Suspected Pulmonary Embolism In A Tertiary Teaching Hospital
Primary aim: To assess the safety of a newly proposed three-tiered clinical decision pathway for investigation of pulmonary embolism (PE), and to assess its potential to reduce unnecessary radiological investigations without increasing risk of missed PE.
Secondary aims: To retrospectively compare the performance of two selected clinical decision rules, the PERC rule and the RGS, with clinician gestalt in predicting the likelihood of PE in patients previously investigated with computed tomography pulmonary angiography (CTPA) or ventilation-perfusion (V/Q) scanning at the Royal Adelaide Hospital (RAH) over a 6-month period.
A retrospective study was conducted applying PERC and RGS to 584 emergency department (ED) based patient encounters where suspected PE was investigated radiologically, at the Royal Adelaide Hospital from May to November 2015. Studies were confined to emergency presentations where acute PE was suspected; inpatients and follow-up studies for resolution of PE were excluded. Sensitivity, specificity, positive and negative predictive values of the proposed three-tiered clinical decision pathway were calculated.
Complete data was obtained for 584 ED based patient encounters where suspected PE was investigated radiologically. 79 patients had radiological evidence of PE; a prevalence of 13.5%. Applied retrospectively, the proposed three-tiered clinical decision rule had a negative predictive value (NPV) of 97.7% and a sensitivity of 98.5% for radiologically proven PE. Applying the pathway, 44 of 476 scans (9.2%) could have been avoided but a single case of PE would have been missed; a false-negative rate of 1.5%.
The proposed three-tiered clinical decision rule appears safe in risk-stratifying patients prior to radiological investigation of PE and may prevent a proportion of unnecessary scans from being ordered.