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Title: Assessment of prognostic models for patients with acute pulmonary embolism
Author: Elias, Antoine
Awarding Body: University of Oxford
Current Institution: University of Oxford
Date of Award: 2016
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Background: Acute pulmonary embolism (PE) is a life-threatening condition. This thesis presents my research into the role of prognostic models and strategies for assessing the severity of acute PE, how these compare with recommendations in clinical guidelines and the role of physician's clinical judgment for improving patient management. Methods: Methods used in each element in the research were appropriate to the relevant objectives: systematic reviews for assessing prognostic markers and prognostic models; sensitivity analysis using the net benefit decision-analytic measure across a range of threshold values for low-risk PE categories in direct comparisons; survey of clinical practice; development and assessment of a case-ascertainment strategy to detect PE patients in one hospital and to explore selection bias; and development of a study protocol for a future comparative study. Findings: Individual prognostic markers are insufficient on their own to accurately predict outcome. Prognostic models are more successful, with the PE severity index (PESI) and simplified PESI (sPESI) models being the most validated. They provided a low event rate in patients identified as low-risk, which was similar to that obtained with other, less validated, strategies, such as the Hestia hospital checklist. High-risk groups were best identified using PESI or other models at high cut-off levels or by adding clinical vital signs, biomarkers and imaging-based markers of right ventricular dysfunction/ myocardial ischemia. The net benefit analysis confirmed the superiority of PESI and sPESI over original competing models, and the incremental value of adding prognostic markers. The survey showed that emergency physicians still rely mostly on their own clinical judgment when deciding about early discharge or complete outpatient management and the case-ascertainment study showed that if case-ascertainment is incomplete, selection bias may mean that event rates and prognosis will be underestimated, prognostic models will be overoptimistic and the results of different studies cannot be compared, contrasted or combined reliably. Conclusions: Based on current evidence, the PESI models are the most appropriate strategies for deciding on early discharge and outpatient management for patients presenting to hospital with acute PE. Future research, with complete case-ascertainment, needs to compare these models with Hestia and clinical judgement to assess their value for decisions about the management of non-selected PE patients.
Supervisor: Clarke, Michael ; Mismetti, Patrick Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available
Keywords: Prognosis ; Pulmonary embolism ; Prediction