Overutilization of CT Pulmonary Angiogram for Diagnosis of Pulmonary Embolism - Opportunities for Improvement

Abstract

PURPOSE: Clinical manifestation of pulmonary embolism (PE) is non-specific and the physician's judgment is often inaccurate. Though CTPA (CT Pulmonary Angiography) is the gold standard, the Prospective Investigation of Pulmonary Embolism Diagnosis (PIOPED II) study advocated conservative use of CTPA based on high pretest probability. However, despite the cost and complications, CTPA is often abused. The purpose of the study is to examine if CTPA was appropriately utilized based on Revised Geneva Score (RGS) and validated algorithm. METHODS: Retrospective chart review of 281 patients who had a CTPA during the period between 12/09 and 08/10 for suspected PE. Relevant information to address the study hypothesis was collected. Patients were stratified into Low, Intermediate and High pretest probability for PE after calculating RGS. RESULTS: There were 281 patients with 96 (34%) males and 185 (66%) females. The median age was 63 years (range 21-101). RGS for individual patients ranged from 0-13. 111 (39.5%) were in Low pretest probability ( 3), 149 (53%) in Intermediate (4-10) and 21 (7.1%) in High ( 11). PE was diagnosed in 4/111 (3.6%) of low probability category, 39/149 (26%) of intermediate, and in 10/21 (47.6%) of high probability category. The overall prevalence of PE was found to be 18.8%. D-dimer assay was obtained in 80 patients (28.4%). Though D-dimer was not done in all patients, no patient with normal D-dimer had PE (high sensitivity). Contrast induced Nephropathy was noted in 8 (2.8 %) and IV site infiltration of contrast in 4 (1.4%). CONCLUSIONS: RGS is an easy to use and a reliable tool to assess the pre-test probability of PE. This tool is independent of the doctor's experience applying the rule. In patients with low pretest clinical probability of PE, normal D-dimer has a high predictive value for excluding PE and obviates further diagnostic work-up. CLINICAL IMPLICATIONS: Revised Geneva score and judicious use of D-dimer are superior to physician judgment in diagnosis of PE and help promote optimal, safe and cost-effective care.