Fewer CT exams hold key to curbing PE overdiagnosis

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 - CTA of pulmonary embolism
CTA showing pulmonary embolus in 48-year-old man.
Source: Radiology 2012; 263: 271-8

The advent of CT pulmonary angiography may have spurred overdiagnosis of pulmonary embolism (PE), according to an analysis published July 2 in BMJ. The authors detailed a three-step plan to reduce overdiagnosis.

When it arrived on the market in 1998, multidetector CT pulmonary angiography seemed like it might provide a solution to the conundrum of PE assessment. The new technology outperformed ventilation-perfusion scanning by delivering higher resolution images and more definitive results.

Use of CT pulmonary angiography exploded among health maintenance beneficiaries from 2001 to 2008 from 0.3 to 4 per 1,000 beneficiaries, according to Renda Soylemez Wiener, MD, from the Pulmonary Center at Boston University School of Medicine, and colleagues. 

Wiener outlined multiple factors propelling use of the exam. PE signs and symptoms are not sensitive or specific, and a missed embolism can be fatal. CT helps physicians avoid a miss. “The widespread availability of CT pulmonary angiography has also encouraged doctors to lower their threshold for looking for pulmonary embolism.”

However, as physicians look for more PEs, they find more PEs. Age-adjusted incidence of PE had been steady in the five years prior to the introduction of CT pulmonary angiography, according to Wiener et al. It increased by 80 percent in the next eight years, but age-adjusted mortality did not budge.

Overdiagnosis of PE is associated with multiple harms, including complications of anticoagulation as well as patient inconvenience and anxiety.

Wiener and colleagues offered a three-step plan to improve PE diagnosis. They recommended:

  • Using algorithms and D-dimer results in the ordering process to better target CT pulmonary angiography to patients with a higher likelihood of PE;
  • Using ventilation perfusion imaging or Doppler ultrasound as a first line exam for clinically stable patients; and  
  • Considering not treating stable patients with isolated subsegmental PE and adequate cardiopulmonary reserve.

The authors called for a prospective cohort study to determine the safety of withholding treatment for certain patients with isolated PE.