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ELOPE: A Look at Patient-Centered Outcomes One Year After Pulmonary Embolism
One year after a pulmonary embolism (PE), patients tend to have less dyspnea, better quality of life (QOL), and improved walking capacity compared to what is reported at the time of the acute event, according to results from the ELOPE (Evaluation of Long-term Outcomes after PE) study presented at the ASH annual meeting last month. Most of the improvement was observed within the first three months after PE diagnosis, but patients with poor oxygen uptake (or the rate of oxygen consumption measured during incremental exercise; a reflection of physical fitness) had less improvement in these outcomes – and, in some cases, even worsening), the authors, led by Susan R. Kahn, MD, MSc, from the Center for Clinical Epidemiology at McGill University in Montreal, Canada, noted.
"Most PE research has focused on outcomes such as mortality and PE recurrence," Dr. Kahn and co-authors wrote. "Patient-centered outcomes such as persistent dyspnea, impaired QOL, and reduced walking capacity after PE have been largely unstudied."
The prospective, observational, multicenter ELOPE trial addressed this knowledge gap, looking specifically at these outcomes after one year in 100 patients (mean age = 50 years old) with a first episode of acute PE who were recruited from five Canadian centers. Patients were excluded from the study if they had sub-segmental–only PE, preexisting severe cardiopulmonary comorbidity, previous proximal deep-vein thrombosis (DVT), contraindication to CT pulmonary angiography, and a life expectancy of less than one year.
Most of the patients (80%) were outpatients, and 33 percent had concomitant DVT. PE was provoked in 21 percent of cases (meaning there was an identifiable risk factor that likely caused the PE) and unprovoked in 79 percent (the absence of an identifiable risk factor for PE). None of the incidences of PE were cancer-related.
Dr. Kahn and colleagues assessed patients at baseline (the first visit for PE), one, three, six, and 12 months after PE, using the following measures to quantify outcomes:
Dyspnea = UCSD Shortness of Breath Questionnaire (SOBQ)
Generic QOL = SF-36
PE-specific QOL = PEmbQoL
Walking capacity = 6-minute walk test (6MWT)
The study's primary outcome was maximal aerobic capacity. Maximal aerobic capacity one year after PE was calculated by comparing a patient's peak oxygen uptake (VO2; measured with a cardiopulmonary exercise testing or a stress test) with the patient's predicted maximal VO2 (VO2max). If a patient's VO2max was <80 percent of his or her predicted VO2max (according to the American Thoracic Society guidelines), the VO2max was considered "abnormal."
During one year of follow-up:
Dyspnea scores improved by an average of 16.9 points on SOBQ (on a scale of 1-120) compared with baseline
QOL was better on both the physical and mental components of the SF-36 PCS (improving by 9.0 and 5.6 points, respectively, on a scale of 1-100)
For PE-specific QOL, the intensity of complaints was reduced by 33.4 points (on the PEmbQoL, on a scale of 1-100)
Walking capacity increased by 43 meters over baseline
"Improvement tended to be more marked during the first three months after PE and tapered off thereafter," the authors noted, adding that patients with abnormal VO2max did not experience improvements in outcomes to the same extent as patients with normal VO2max. "For all measures, degree of improvement was significantly reduced and one-year scores [of maximal aerobic capacity] were significantly worse among the 46.5 percent (40/86) of patients with [abnormal] VO2max."
This group of symptoms is what Dr. Kahn and colleagues, in a separate abstract presented at this year's meeting, refer to as "post-pulmonary embolism syndrome." Again using data from the ELOPE study, the researchers determined that almost half of patients who experience PE can be said to have post-PE syndrome, characterized by exercise limitation, which in turn influences their QOL and degree of dyspnea.
Future analyses, the authors concluded, should focus on identifying clinical, biomarker and imaging-based determinants of dyspnea, poor QOL, and reduced walking capacity in patients with post-PE syndrome.
Kahn SR, Hirsch A, Beddaoui M, et al. Dyspnea, quality of life and walking capacity during 1 year follow-up after a first episode of pulmonary embolism: results of the E.L.O.P.E. study. Abstract #750. Presented at the 2015 ASH Annual Meeting, December 7, 2015; Orlando, Florida.
Kahn SR, Hirsch A, Beddaoui M, et al. "Post-pulmonary embolism syndrome" after a first episode of PE: results of the E.L.O.P.E. study. Abstract #650. Presented at the 2015 ASH Annual Meeting, December 7, 2015; Orlando, Florida.