Diagnostic testing for PE in COPD exacerbation
Background: Patients with chronic obstructive pulmonary disease (COPD) who present with exacerbations have nonspecific symptoms that include productive or nonproductive cough, increased wheezing, or worsening shortness of breath. The clinical assessment encompasses searching for COPD exacerbation triggers such as lower respiratory tract infections, environmental exposures, and pulmonary embolism (PE). This study investigated if active searching for PE would lead to better outcomes in patients with COPD exacerbation.
Methods: The SLICE (Significance of Pulmonary Embolism in COPD Exacerbations) study was a randomized controlled trial that compared an active strategy for diagnosing PE, defined as D-dimer testing and, if positive, performing computed tomography pulmonary angiography (CTPA), plus usual care with usual care alone in patients hospitalized for a COPD exacerbation. The primary outcome was a composite of nonfatal symptomatic venous thromboembolism (VTE), readmission for COPD, or death within 90 days after randomization.
Results: In total, 746 patients were randomized, of whom 98.8% completed the trial (mean age, 70 years; 74% men). The primary outcome occurred in 29.7% of patients in the intervention group and in 29.2% of those in the control group (relative risk, 1.02; 95% CI, 0.82-1.28). Nonfatal new or recurrent VTE was not significantly different in the 2 groups (0.5% vs 2.5%; risk difference, –2.0%; 95% CI, –4.3 to 0.1). By day 90, 25.4% of patients in the intervention group and 22.9% of those in the control group were readmitted for a COPD exacerbation (risk difference, 2.5%; 95% CI, –3.9 to 8.9). Death from any cause occurred in 6.2% of patients in the intervention group and 7.9% of those in the control group (risk difference, –1.7%; 95% CI, –5.7 to 2.3). In patients in whom the intervention strategy was used, the prevalence of PE was 4.3%; among those who had a positive D-dimer test result and then went on to have CTPA, the prevalence of PE was 8.9%.
Conclusions: The authors concluded that among patients hospitalized for an exacerbation of COPD, routinely adding a diagnostic strategy to search for PE alongside usual care did not significantly improve a composite health outcome when compared with usual care alone.
McMaster editors’ comment: Among individuals allocated to the “search for PE” strategy, a high pretest probability for PE was reported in very few patients (0.3%), and low probability, in ~45%. It is not surprising, therefore, that the overall prevalence of PE was so low (4.3%) in this group and no effect on clinical outcomes was observed with this strategy. These findings reaffirm the need for careful selection of patients for diagnostic PE testing, irrespective of the clinical situation, especially as CTPA has become an overused, go-to diagnostic test that has potential harms (radiation exposure, contrast dye toxicity) and is expensive.