PURPOSE: Physician performed 2-point compression ultrasonography (CUS) for diagnosis of deep vein thrombosis (DVT) has been shown to have reasonable accuracy when performed in the emergency department and may be useful in an intensive care setting. As obesity may impact the performance of this test, we assessed the diagnostic test characteristics among the obese patients compared to non-obese patients in the intensive care unit (ICU).
METHODS: Study physicians included 3 critical care fellows and one attending who were blinded to the clinical characteristics of the patients. The CUS protocol consisted of identification and compression of the common femoral and popliteal veins at a single point on each leg. The results were categorized as compressible (negative), non-compressible (positive), or indeterminate. The study ultrasound was done on consecutive patients admitted to the ICU who had a lower extremity ultrasound ordered for the suspicion of DVT. All patients had a duplex ultrasound performed and interpreted by the radiology department, which was used as the reference standard to calculate sensitivity and specificity. We compared the test characteristics among obese patients (BMI >= 30) with non-obese patients (BMI < 30).
RESULTS: A total of 89 studies were included in this analysis. 54 patients with 6 total DVTs were in the obese group and 35 patients with 7 DVTs were in the non-obese group. There were 2 false-positive and 1 false-negative test tests in the obese group with a sensitivity 83% and a specificity of 71%. There were 0 false positive and 2 false negative tests in the non-obese group with a sensitivity of 71% and a specificity of 100%. Although diagnostic accuracy was the same (94%), the non obese group had better agreement (by kappa) with the reference standard (0.80 vs. 0.74).
CONCLUSION: Obesity plays a major role in the diagnostic characteristics of intensivist-performed 2 point CUS to detect DVT.
CLINICAL IMPLICATIONS: Clinicians need to be cognizant of the effect of obesity on the accuracy of CUS in the ICU.
DISCLOSURE: Casey Stahlheber, Consultant fee, speaker bureau, advisory committee, etc. Ousama Dabbagh is on the speaker bureau for Sanofi-Aventis; No Product/Research Disclosure Information