Risk Score Accurately Predicts Heart Events After Major Amputation: Study
Researchers identified that newly derived risk scores can safely predict the risk of myocardial infarction (MI) and major adverse cardiac events (MACE) in patients with major limb amputation resulting from limb ischemia. It has been suggested that the scores can aid clinicians in identifying high-risk patients and minimizing cardiac complications through improved preoperative and perioperative planning. The study was published in the Journal of Vascular Surgery by Lily D. and colleagues.
The analysis was based on data for 15,390 patients, split into a primary cohort (N=10,260) and a validation cohort (N=5,130). All had undergone non-emergent major amputations of the lower limb due to ischemia. Researchers employed univariable and multivariable regression analyses to determine predictors of MI and MACE in hospitalization. Risk scores were developed through weighting variables on the basis of their multivariable logistic regression model beta-coefficients.
The model performance was validated internally through Area Under the Curve (AUC) analysis and Hosmer-Lemeshow goodness-of-fit tests. An additional machine learning analysis also supported variable importance and improved the predictive model.
Risk Variables and Associations
Multivariable analysis identified a number of significant predictors of elevated cardiac risk:
Increasing age (adjusted odds ratio [aOR] for MACE: 1.02 per year; P<.001)
Female gender (aOR: 1.28; P=.01)
Asymptomatic CAD (aOR: 1.36; P=.009)
Symptomatic CAD (aOR: 1.28; P=.049)
CABG more than 5 years ago (aOR: 1.37; P=.014)
Class II CHF (aOR: 1.30; P=.05), Class III CHF (aOR: 1.75; P=.002), Class IV CHF (aOR: 5.26; P<.001)
COPD (aOR: 1.29; P=.012)
Renal insufficiency (aOR: 1.76; P<.001)
End-stage renal disease (ESRD) (aOR: 2.20; P<.001)
For MI-specific analysis, risk factors were:
Age (aOR: 1.02; P=.007)
Asymptomatic CAD (aOR: 1.52; P=.022)
Symptomatic CAD (aOR: 1.56; P=.038)
CABG >5 years ago (aOR: 1.51; P=.029)
Class III CHF (aOR: 1.84; P=.019), Class IV CHF (aOR: 3.07; P=.002)
Renal insufficiency and ESRD on dialysis (both aOR: 1.95; P<.001)
Absence of preoperative antiplatelet therapy was protective (aOR: 0.65; P=.007)
Risk Score Performance and Prognosis
Patients with risk scores of ≤1 experienced only a 2.6% MACE rate, whereas those with ≥16 risk scores were confronted with a 26.9% MACE rate, a 10-fold increase.
For MI, patients with scores of ≤0 experienced an MI rate of merely 0.5%, versus 6.0% in those with scores ≥10, a 12-fold increase.
This research effectively created and validated risk scores for the prediction of myocardial infarction and major adverse cardiac events among those requiring major amputation for limb ischemia. The results identify the importance of comorbid conditions, especially CHF, CAD, and renal disease, in increasing cardiac risk.
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