Hey guys,
Its been far too long for the mini JC series, but thats what happens when you are about to have a baby. This JC was stimulated by Elise, Harwood and my discussion about a cancer patient and the evaluation of pulmonary embolism. I'll set it up for you and you think about how you would evaluate the patient.
65 y/o F presents to the ED with shortness of breath. She says this started 2 days ago, and has worsened since that time. She is a breast cancer survivor and is undergoing active chemotherapy. She is not on home O2, but she has smoked and does think she has COPD as evidenced by her inhalers.
VSS: 95, 95% on RA, 110/70, 37.1 (R), 18 (real) FSG 99
Lungs are reduced BS at bases otherwise unremarkable
She has no signs or symptoms of DVT, she has never had a blood clot, no recent surgeries.
What labs and imaging studies do you want?? (US machine is broken sorry!)
SO today's study is the CHristopher study looking at the evaluation of pulmonary embolism in the emergency department.
Van Belle A et al. Effectiveness of managing suspected pulmonary embolism using an algorithm combining clinical probability, D-dimer testing, and computed tomography. JAMA 2006. 11; 295(2): 172-9.
1. Why is this topic important?
Pulmonary embolism is a commonly feared diagnosis in emergency departments in the United States. The frequency with which pulmonary embolism has been diagnosed has increased over the past ten years, with the number of massive and sub-massive pulmonary embolisms remaining relatively unchanged. This is due in large part to the over zealous testing, and the subsequent diagnosis of likely non-clinically significant pulmonary embolism. A simplified dichotomized clinical decision rule, D-dimer testing and computed tomography may reduce the number of unneeded evaluations for pulmonary embolism in the United States today.
2. What does the study attempt to show?
Consecutive patients in whom the treating physician suspected the possibility of pulmonary embolism, defined as sudden onset of dyspnea, sudden deterioration of existing dyspnea or sudden onset of pleuritic chest pain, without another apparent cause, could be potentially included in this study. The study then applied the wells score, dichotomizing patients into pulmonary embolism unlikely (score <4) and pulmonary embolism likely (score >/= 4). In all patients with a wells score of less than 4, a d-dimer test was applied, with the cutoff of >/= 500ng/mL being considered positive. If the d-dimer was negative, no further investigation was obtained, but if the d-dimer was positive, or if the wells score was >/= 4 a CT was obtained to evaluate for the diagnosis of pulmonary embolism. The study attempts to demonstrate that using this simplified dichotimzed approach to the wells score <4, and a negative d-dimer assay patients can be safely discharged home without further diagnostic evaluation.
3. What are the key findings?
3306 study patients were eligible for inclusion, and 2206 patients (66.7%) were classified as unlikely as having a pulmonary embolism using the dichotomized wells score and underwent d-dimer testing. 1057 patients had a normal d-dimer, and 1028 (32%) were not treated with anti-coagulation. Subsequent nonfatal venous thromboembolism (VTE) occurred in 5 patients (0.5% [95% CI 0.2%-1.1%]) no patients in this group died from a pulmonary embolism at 3-month follow-up.
In the high-risk wells group (wells score >/= 4) 674 patients (20.4%) were included. CT excluded pulmonary embolism in 1505, of which 1,436 patients were not treated with anti-coagulants; with a 3-month incidence of VTE of 1.3% (95% CI, 0.7%-2.0%). In patients in whom the initial CT scan was negative, PE was considered a possible cause of death in 7 (0.5% [95% CI, 0.2%-1.0%]). Overall 674 patients (20.3%) were diagnosed with a pulmonary embolism in patients included in this study cohort.
4. How is patient care impacted?
This study demonstrates that in patients in whom a physician suspects the diagnosis of pulmonary embolism, the use of a dichotomized wells score < 4 and a negative d-dimer assay negate further evaluation for pulmonary embolism, with a < 1% incidence of VTE at 3-months, and no fatal pulmonary embolisms identified at follow-up.
5. Is this an area of controversy?
The evaluation for pulmonary embolism continues to produce anxiety amongst emergency physicians. However, one of the most striking finding in this study is that the overall incidence of pulmonary embolism was 20%. Compare this to the PERC study by Dr. Kline in which the incidence was 7%, this is almost a 3-fold increase in the number of patients with pulmonary embolism. In addition, just 0.15% of patients in the Kline cohort ultimately died from pulmonary embolism, where in the Christopher Study mentioned here 0.5% died from fatal pulmonary embolism. This suggests that emergency physicians, particularly in the United States, evaluate for pulmonary embolism in a lower risk cohort than physicians in other countries. This occurs despite the fact that there is no mortality benefit, and there is a potential for harm.
6. What are the major limitations of the study?
Several patients received anti-coagulation despite being low risk for pulmonary embolism, or having been excluded for pulmonary embolism for other pathologic causes. This could have reduced the number of VTE identified at three months in the negative, or low risk cohorts. Also, the type of CT detector used was not standardized, and the d-dimer assay varied by site. These represent potential confounders of the study results. However, the generalizability of the study and the large number of patients included with few exclusion criteria make this an important piece of the literature for emergency medicine physicians.
Reviewed by David Barounis
So I know this was written more research-like and I apologize, but the end result is what are you going to do about evaluation of PE in the above patient.
I think in our patient her wells score was between 1.5 (active cancer) and a 4 (if you said diagnosis is PE or at least as likely). If you got a trop and a BNP and they were both normal (< 0.02, and a BNP< 100) would you feel better? I think I would, and a diagnosis of PE in my mind is < 2%. However I don't think its unreasonable to get a d-dimer, and if you have a negative d-dimer, a neg trop and a neg BNP in this patient population I think the above study suggests you really do not need to CT scan these patients to look for PE. I think many people would not even get a d-dimer either. Far too often I think d-dimer is used in the ultra low risk patient or "0" risk patient, instead of the patient it was meant for, which is our wells score <4 patients.
-Dave