A newly derived risk model for CABG operative mortality was more accurate than a ready-made model (ROC 0.78 vs 0.76; P<0.05) and prevented underestimation of risk-adjusted mortality.
Cohort (n=7,491)
Yes
Does recalibrating or remodeling risk indexes improve the accuracy of risk-adjusted operative mortality predictions in CABG patients compared to a ready-made model?
Existing risk indexes for cardiac surgery should be episodically recalibrated or remodeled using local data to prevent biased risk-adjusted operative mortality calculations and inaccurate surgeon profiling.
Absolute Event Rate: 0.78% vs 0.76%
p-value: p=<0.05
BACKGROUND: Risk indexes for operative mortality after cardiac surgery are used for comparative profiling of surgeons or centers. We examined whether clinicians and managers should use an existing index without modification, recalibrate it for their populations, or derive a new model altogether. METHODS AND RESULTS: Drawing on 7491 consecutive patients who underwent isolated CABG at 2 Toronto teaching hospitals between 1993 and 1996, we compared 3 strategies: (1) using a ready-made model originally derived and validated in our jurisdiction; (2) recalibrating the ready-made model to better fit the population; and (3) deriving a new model with additional risk factors. We assessed statistical accuracy, ie, area under a receiver-operator characteristic curve (ROC); precision, ie, statistical goodness-of-fit; and actual impact on both risk-adjusted operative mortalities (RAOM) and performance rankings for 14 surgeons. The new model was slightly more accurate than the ready-made model (ROC, 0.78 versus 0.76; P<0.05), albeit not different from the recalibrated model (ROC, 0.77). The ready-made model showed poor fit between the predicted and observed results (P<0.001), leading to significant underestimation of RAOM (1.6+/-0. 2%) compared with the other strategies (2.5+/-0.2%; P=0.048). Remodeling also changed the performance rankings among half the surgeons with higher RAOM. CONCLUSIONS: Poorly calibrated risk algorithms can bias the calculation of RAOM and alter the results of surgeon-specific profiles. Any existing index used for risk assessment in cardiac surgery should be episodically recalibrated or compared with new models derived from local subjects to ensure that its performance remains optimal.
Ivanov et al. (Tue,) conducted a cohort in Operative mortality after isolated CABG (n=7,491). New derived risk model vs. Ready-made risk model was evaluated on Statistical accuracy (area under ROC curve) (p=<0.05). A newly derived risk model for CABG operative mortality was more accurate than a ready-made model (ROC 0.78 vs 0.76; P<0.05) and prevented underestimation of risk-adjusted mortality.