Changing trends in venous thromboembolism-related imaging in Western Australian teaching hospitals, 2002-2010

Objective: To determine trends in referral for venous thromboembolism (VTE) imaging in Western Australian teaching hospitals. Design and setting: Retrospective audit of the WA picture archiving and communication system, PathWest Laboratory Medicine records, the hospital morbidity database at the four adult teaching hospitals in Perth, WA, and the WA death registry. Patients: All patients referred for VTE-related imaging, and all hospital separations for pulmonary embolism (PE) during 2002-2010. Main outcome measures: Number of referrals for computed tomography pulmonary angiography (CTPA), ventilation perfusion lung scintigraphy, leg ultrasound and plasma D-dimer assay; hospital separations for PE and deaths from PE. Results: Referrals for VTE-related imaging increased by 34%, while PE-related imaging increased by 65% during the study period, owing entirely to referrals for CTPA, which increased by more than 500%. The number of hospital separations for PE increased by 45% over the same period and the prevalence of PE among referred patients felt from 22.1% in 2002 to 19.5% in 2010. There was no fall in the death rate from PE in WA during the study period (P = 0.19). The number of D-dimer tests performed in the same hospitals increased by 42% over the study period. Conclusions: The increased number of referrals for PE-related imaging resulted in more diagnoses but no reduction in deaths from PE in WA. Widespread D-dimer testing did not reduce referrals for imaging and is likely to have resulted in increased referrals. Increased imaging leads to overdiagnosis of clinically insignificant PE, and alternative strategies are required to reduce PE death rates.