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

Background:  Most pulmonary embolism (PE) research has focused on outcomes such as mortality and PE recurrence. Patient-centered outcomes such as persistent dyspnea, impaired quality of life (QOL) and reduced walking capacity after PE have been largely unstudied. To address this knowledge gap, we performed the ELOPE (Evaluation of Longterm Outcomes after PE) study, a prospective, observational, multicenter cohort study of long-term outcomes after acute PE (www.clinicaltrials.gov NCT01174628).

Objectives: To describe and quantify dyspnea, quality of life and walking capacity during the 1 year following PE diagnosis.

Methods: Patients ³ 18 years old with a 1^st episode of acute PE diagnosed within the previous 10 days screened at 5 Canadian recruiting centers were potentially eligible to participate.  Exclusion criteria were subsegmental-only PE, preexisting severe cardiopulmonary comorbidity, previous proximal DVT, contraindication to CT pulmonary angiography, life expectancy <1 year, unable to read questionnaire in English and French or to attend follow-up visits, and unable or unwilling to consent.  

At baseline, 1, 3, 6 and 12 months after PE, we measured dyspnea (UCSD Shortness of Breath Questionnaire [SOBQ]), generic QOL (SF-36), PE-specific QOL (PEmbQoL), and walking capacity (6-minute walk test (6MWT)).  Cardiopulmonary exercise testing (CPET) was performed at 1 year; the primary outcome of the study was maximal aerobic capacity defined by peak oxygen uptake (VO2) as a percent of predicted maximal VO2 (VO2max) on 1-year CPET, with <80% predicted VO2max considered abnormal, as per American Thoracic Society guidelines.

 

For this analysis, we summarized demographic and clinical characteristics of study subjects, and calculated mean (SD) dyspnea scores, QOL scores and 6MWT distance at each study visit during 1 year follow-up in the total population and according to 1-year CPET result.

Results: 984 patients were screened for participation; of these, 150 were eligible and 100 (67%) consented to participate. Mean (SD) age was 50 (15) years, 57% were male, 80% were outpatients and 33% had concomitant DVT. PE was provoked in 21% and unprovoked in 79%; none were cancer-related.

During 1 year follow-up, SOBQ scores improved by an average of 16.9 points compared with baseline, SF-36 PCS (physical component score) by 9.0 points, SF-36 MCS (mental component score) by 5.6 points, PEmbQoL (e.g. intensity of complaints dimension) by 33.4 points, and 6MWT by 43 meters.  Improvement tended to be more marked during the first 3 months after PE and tapered off thereafter.  For all measures, degree of improvement was significantly reduced and 1 year scores were significantly worse among the 46.5% (40/86) of patients with <80% predicted VO2max on 1-year CPET (e.g., SF-36 PCS: see Figure).

Conclusions:  On average, dyspnea, QOL and walking capacity improve during the year after PE, most notably during the first 3 months after PE diagnosis. However, those patients with abnormal VO2max at 1 year had less improvement over time and worse 1 year scores for all measures, compared to those with normal VO2max at 1 year. Further analyses will focus on identifying clinical, biomarker and imaging-based determinants of dyspnea, poor QOL and reduced walking capacity at 1 year after PE.

Funding: Canadian Institutes of Health Research (MOP-93627)