Determining the minimal clinically important difference for the PEmbQoL questionnaire, a measure of pulmonary embolism-specific quality of life.

Background Pulmonary embolism (PE) reduces quality of life (QOL). The PEmbQoL questionnaire, a PE-related QOL measure, was recently developed and validated and has been used to quantify disease-specific QOL in clinical studies of patients with PE. However, to date, interpretation of PEmbQoL scores has been limited by a lack of information on the minimal clinically important difference (MCID) of this measure. Objective To determine the MCID for PEmbQoL and its subscales using anchor-based and distribution-based approaches. Methods We analyzed data from the ELOPE Study, a prospective, multicenter cohort study of long-term outcomes after a first episode of acute PE. At baseline and 1, 3, 6 and 12 months after PE, we measured generic QOL (SF-36), PE-specific QOL (PEmbQoL) and dyspnea severity (UCSD Shortness of Breath Questionnaire). We used time-varying repeated-measures mixed-effect models to estimate anchor-based MCID and effect sizes to estimate distribution-based MCID. Results Eighty-two patients participated in this sub-study. Their mean age was 49.4 years, 60% were male and 84% had PE diagnosed in an outpatient setting. Using both anchor- and distribution-based approaches, the MCID for PEmbQoL appears to be 15 points. Based on this MCID, 42%, 59%, 66% and 75% of patients experienced at least one MCID unit of improvement in PEmbQoL from baseline to 1, 3, 6 and 12 months, respectively. Conclusion Our results provide new information on the MCID of PEmbQoL, a PE-specific QOL questionnaire that can be used by researchers and clinicians to measure and interpret changes in PE-specific QOL over time, or as an outcome in clinical trials.