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By Shanti M. Pinto, MD

During my residency at an inpatient rehabilitation (IPR) center, we used Doppler ultrasound to screen almost every new patient for venous thromboembolism (VTE), even if they didn’t have symptoms. We wanted to identify VTE before patients suffered a life-threatening pulmonary embolism. But we wondered if the screening was worthwhile, because it seemed expensive and turned up relatively few VTEs.

This question has been echoed by many providers looking for efficient ways to prevent pulmonary embolism. My colleagues and I are uncovering the answer: We published a 2018 paper showing that routine Doppler ultrasound improves outcomes and is cost-effective.

Proactive Screening for Deep Vein Thrombosis

There’s controversy among rehabilitation providers about whether patients should be screened for deep vein thrombosis (DVT) at IPR without showing symptoms. To answer this question, we examined the electronic medical records of 2,312 patients at an IPR facility that specializes in patients with brain injury, spinal cord injury and stroke. This facility takes a proactive approach: using Doppler ultrasound to screen patients for lower-limb DVT as part of the admission process.

Early Diagnosis Improves Outcomes

Our first goal was to see if earlier DVT diagnosis affects patient outcomes.

Of the patients in our study, 145 (6.6 percent) were found to have DVT during admission. Those patients were immediately prescribed anticoagulants unless contraindicated. Another 37 patients (1.7 percent) were diagnosed after showing DVT symptoms later in IPR.

The patients diagnosed with DVT on admission were:

  • Far less likely to suffer pulmonary embolism, which affected 3.7 percent of patients diagnosed on admission. Pulmonary embolism affected 48 percent of patients who weren’t diagnosed until they showed DVT symptoms.
  • Significantly less likely to need acute hospital care: 12 percent of patients diagnosed on admission were readmitted to the hospital for acute care, compared to 35.1 percent of patients who were diagnosed later in IPR.
  • Spending less time in IPR: Patients diagnosed on admission spent an average of 18.96 days in IPR, versus 26 days for patients diagnosed later.

Why Doppler Ultrasound Is Cost-Effective

Shorter stays, fewer pulmonary embolisms and fewer acute-care transfers are better for patients and reduce the cost of care. We wanted to see how prevalent VTE needs to be for these cost savings to offset Doppler ultrasound’s costs.

We built a statistical model comparing the cost of IPR at a hypothetical facility where initial Doppler ultrasound is routine, to the cost of care at a facility that uses a clinical strategy to diagnose DVT after symptoms are found. Our study posited a 6.7 percent probability that initial screening uncovers VTE – a conservative estimate.

The costs were almost identical: $20,265 per admission when Doppler ultrasound is routine versus $20,269 per admission when a clinical strategy is used instead. And that actually overestimates the cost of routine screening because our model doesn’t include the price of hospital readmission. (That information wasn’t available in the literature or at the center we studied.)

More generally, our analysis suggests that routine Doppler ultrasound becomes cost-effective when the probability of VTE is 6 percent or higher. And the higher the rate of DVT, the more cost-effective it becomes because more VTEs are found.

Advancing Evidence-Based Care

Doppler ultrasound is a standard part of admission at Carolinas Rehabilitation. Our study confirmed this is a sound approach here and at other leading centers. This marks the latest step in making sure our practices are based on solid evidence. And we hope our findings inspire more centers to embrace routine Doppler screening – we want to help as many patients as possible, no matter which healthcare system they visit.

Read the paper in the American Journal of Physical Medicine and Rehabilitation.

To learn more about the Doppler ultrasound technique and the difference it can make, contact Dr. Shanti Pinto at Shanti.Pinto@AtriumHealth.org.

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