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A3764 - “Are We CAT-o-Maniac?” Study of Appropriateness of CT-Angiography of Chest to Rule Out Pulmonary Embolism in Patients with Suspected PE
Author Block: I. A. Lalani, R. Raj, R. Annam, M. Doraiswamy, M. H. Eng; Department of Internal Medicine, Monmouth Medical Center, Long Branch, NJ, United States.
Rationale: Venous thromboembolism affects more than half a million Americans every year and accounts for the third leading cause of blood vessel disorder after myocardial infarction and stroke. Pulmonary embolism (PE) can be catastrophic as it has high mortality rate. In the current medical practice, considering the legal consequences of a missed medical diagnosis, clinicians often have low threshold for invasive work up in form of CT pulmonary angiography (CTPA) to rule in or rule out PE. Methods:Our study is a retrospective patient chart review in a community teaching hospital. Patients who underwent CTPA between over a two-year time frame were included in the study. To assess the appropriateness of CTPA, we have utilized Modified Wells’ Criteria and Revised Geneva Score. These algorithms help to stratify the patients to low, intermediate or high pretest probability (PTP) for PE. A sequential test for a d-dimer level if the PTP is low or intermediate. If this sequence is not followed, then we considered, CTPA to be inappropriately ordered. For patients with low PTP, if they have satisfied pulmonary embolism rule out criteria (PERC) then no further testing is needed. We considered age adjusted d-dimer results as the cut-off for normal limit if the results are available. Results: We analyzed 275 patient charts who received CTPA and excluded the patients who had previous history of PE. The final study population was 259 patients which comprised of 95 males (36.7%) and 164 females (63.7%). The mean age of the study population was 64.8 years with SD of 15.8 years. Study population had 75.3% Caucasians, 17.3% African Americans and rest were other races. 39 patients (15%) had appropriately received CTPA as compared to inappropriate testing in 220 patients (85%). Majority of inappropriate testing was due to lack of d-dimer testing. If the crude probability of d-dimer test being positive or negative is considered as 50%, we could have potentially ruled out PE in about half of the patients with inappropriately ordered CTPA. With doing d-dimers, we could have prevented unnecessary testing and subsequent contrast/radiation exposure to patients. There were several instances where age adjusted d-dimer results were not considered.Conclusion: We identified a pattern where simple non-invasive blood test of d-dimer was not performed which could help rule out diagnosis of PE. Introduction of a pop-up window within the Electronic Medical Records for calculating PTP and sequential d-dimer prior to ordering CTPA will prevent unnecessary testing.