title: Development and validation of a time-dependent risk model for predicting mortality in infective endocarditis.
abstract: OBJECTIVE
  Existing risk models in infective endocarditis (IE) have not investigated whether the prognostic value of clinical parameters is time-dependent. We have explored the potential of time-dependent risk stratification to predict outcome in IE.
  
  
  RESULTS
  We studied 273 patients admitted with IE to two centres (derivation cohort n=192, validation cohort n=81). The derivation cohort was used to identify independent predictors of 6 months mortality at days 1, 8, and 15 (multivariable Cox regression, P<0.05). There were six predictors at day 1, five at day 8, and only three at day 15. Whereas heart failure, thrombocytopenia, and severe comorbidity predicted mortality at all three time-points, other predictors were time-dependent (age, tachycardia, renal impairment at day 1; severe embolic events, renal impairment at day 8). These predictors were incorporated into a time-dependent model. The model was validated in an independent cohort with concordance indices of 0.79 (95% CI 0.68-0.91) at day 1, 0.79 (95% CI 0.65-0.93) at day 8, and 0.84 (95% CI 0.73-0.95) at day 15. Six months mortality was 2.4% in patients deemed as low-risk at all time-points, compared with 78.2% in patients classified as high-risk at any evaluation.
  
  
  CONCLUSIONS
  Prognostic factors in IE are time-dependent. Time-dependent risk stratification accurately predicts outcome in IE.
authors.affiliation: Department of Cardiology, 3rd floor West, Concord Repatriation General Hospital, Sydney South Western Area Health Service, University of Sydney, Hospital Rd, Concord, NSW 2139, Australia.
authors.forename: Raymond W
authors.initials: RW
authors.lastname: Sy
authors.forename: Chirapan
authors.initials: C
authors.lastname: Chawantanpipat
authors.forename: David R
authors.initials: DR
authors.lastname: Richmond
authors.forename: Leonard
authors.initials: L
authors.lastname: Kritharides