Innovative Inflammatory Burden Index for identification of high mortality risk in patients with pulmonary embolism: a large retrospective cohort study

BACKGROUND: The prognostic significance of systemic inflammation in pulmonary embolism (PE) remains unclear. This study aimed to evaluate the predictive value of a novel Inflammatory Burden Index (IBI) for long-term mortality in patients with acute PE. METHODS: A total of 1642 patients with acute PE were retrospectively analysed. The optimal cut-off for IBI was determined using maximally selected rank statistics. The association between high IBI and all-cause mortality was assessed using multivariable Cox proportional hazards models. The predictive performance of IBI and its individual components was compared using time-dependent receiver operating characteristic (ROC) curves. Variable importance for mortality prediction was further evaluated using random survival forest (RSF) analysis. RESULTS: During a median follow-up of 41.2 months, 262 patients (16.0%) died. High IBI was independently associated with increased risk of all-cause mortality (adjusted HR 2.33, 95% CI 1.78 to 3.04; p